Natalie Gasson - Profile on Academia.edu (original) (raw)

Papers by Natalie Gasson

Research paper thumbnail of Does Parkinson's Disease Moderate the Relationship Between Disrupted Sleep and Cognition? A Case-Controlled Polysomnographic Study

Does Parkinson's Disease Moderate the Relationship Between Disrupted Sleep and Cognition? A Case-Controlled Polysomnographic Study

Journal of Sleep Research, 2016

Research paper thumbnail of Cognitive Reserve, Executive Function, and Memory in Parkinson’s Disease

Cognitive impairment is acknowledged as a feature of Parkinson’s disease (PD), and the most commo... more Cognitive impairment is acknowledged as a feature of Parkinson’s disease (PD), and the most common cognitive declines are in executive function (EF) and memory. Cognitive reserve (CR) may offer some protection against cognitive dysfunction in PD. The present study used two proxies of CR (years of education, premorbid IQ) to examine the relationship between CR and (i) EF (ii) memory in a large PD sample (n = 334). Two aspects of EF were examined, including verbal fluency and planning skills. Two aspects of verbal memory were examined, including immediate recall and delayed recall. For EF, both CR proxies significantly predicted verbal fluency, but only years of education predicted planning skills. Years of education significantly predicted immediate recall, but premorbid IQ did not. Neither CR proxy predicted delayed recall. These findings suggest that CR, in particular years of education, may contribute to EF and memory function in those with PD. A key finding of this study is the v...

Research paper thumbnail of doi: 10.3389/fpsyg.2015.00105 The measurement of psychological literacy: a first approximation

doi: 10.3389/fpsyg.2015.00105 The measurement of psychological literacy: a first approximation

Psychological literacy, the ability to apply psychological knowledge to personal, family, occupat... more Psychological literacy, the ability to apply psychological knowledge to personal, family, occupational, community and societal challenges, is promoted as the primary outcome of an undergraduate education in psychology. As the concept of psychological literacy becomes increasingly adopted as the core business of undergraduate psychology training courses world-wide, there is urgent need for the construct to be accurately measured so that student and institutional level progress can be assessed and monitored. Key to the measurement of psychological literacy is determining the underlying factor-structure of psychological literacy. In this paper we provide a first approximation of the measurement of psychological literacy by identifying and evaluating self-report measures for psychological literacy. Multi-item and single-item self-report measures of each of the proposed nine dimensions of psychological literacy were completed by two samples (N = 218 and N = 381) of undergraduate psycholo...

Research paper thumbnail of A Longitudinal Investigation of the Development of Fullterm, Preterm and 'At-Risk' Infants from Birth to Four Years using a Parent Report Measure

A Longitudinal Investigation of the Development of Fullterm, Preterm and 'At-Risk' Infants from Birth to Four Years using a Parent Report Measure

Research paper thumbnail of Motor Heterogeneity in Parkinson's Disease: A Bayesian Perspective

Motor Heterogeneity in Parkinson's Disease: A Bayesian Perspective

Movement Disorders, 2017

Research paper thumbnail of Self-Reported Sleep Differentially Predicts Memory and Executive Function in Younger and Older-Onset Parkinson's Disease

Self-Reported Sleep Differentially Predicts Memory and Executive Function in Younger and Older-Onset Parkinson's Disease

Research paper thumbnail of Measuring General Expectations of Advanced Stage Treatment Outcomes in Parkinson’s Disease

Measuring General Expectations of Advanced Stage Treatment Outcomes in Parkinson’s Disease

Journal of Parkinson's Disease

Background: Recent research suggests that a significant number of those who receive advanced trea... more Background: Recent research suggests that a significant number of those who receive advanced treatments for Parkinson’s disease (PD) do not report improvements for some symptoms, which may relate to their pre-treatment expectations. It is important that expectations of treatment are measured and discussed prior to advanced treatment. Objective: The primary aim of this study was to develop a measure of treatment expectations of two advanced-stage treatments in PD, deep brain stimulation (DBS), and Levodopa/Carbidopa Intestinal Gel (LCIG). A secondary aim was to explore potential predictors of treatment expectations. Methods: The questionnaire-based measure was developed by researchers in conjunction with a highly experienced clinician, and evaluated treatment expectations in 189 people aged 46–91 years (M = 71.35, SD = 8.73; 61% male) with idiopathic PD. Results: The overall measure demonstrated excellent internal consistency (α= 0.96). Exploratory factor analysis suggested the scale...

Research paper thumbnail of Beyond factor analysis: Multidimensionality and the Parkinson’s Disease Sleep Scale-Revised

PLOS ONE, Feb 12, 2018

Many studies have sought to describe the relationship between sleep disturbance and cognition in ... more Many studies have sought to describe the relationship between sleep disturbance and cognition in Parkinson's disease (PD). The Parkinson's Disease Sleep Scale (PDSS) and its variants (the Parkinson's disease Sleep Scale-Revised; PDSS-R, and the Parkinson's Disease Sleep Scale-2; PDSS-2) quantify a range of symptoms impacting sleep in only 15 items. However, data from these scales may be problematic as included items have considerable conceptual breadth, and there may be overlap in the constructs assessed. Multidimensional measurement models, accounting for the tendency for items to measure multiple constructs, may be useful more accurately to model variance than traditional confirmatory factor analysis. In the present study, we tested the hypothesis that a multidimensional model (a bifactor model) is more appropriate than traditional factor analysis for data generated by these types of scales, using data collected using the PDSS-R as an exemplar. 166 participants diagnosed with idiopathic PD participated in this study. Using PDSS-R data, we compared three models: a unidimensional model; a 3-factor model consisting of sub-factors measuring insomnia, motor symptoms and obstructive sleep apnoea (OSA) and REM sleep behaviour disorder (RBD) symptoms; and, a confirmatory bifactor model with both a general factor and the same three sub-factors. Only the confirmatory bifactor model achieved satisfactory model fit, suggesting that PDSS-R data are multidimensional. There were differential associations between factor scores and patient characteristics, suggesting that some PDSS-R items, but not others, are influenced by mood and personality in addition to sleep symptoms. Multidimensional measurement models may also be a helpful tool in the PDSS and the PDSS-2 scales and may improve the sensitivity of these instruments.

Research paper thumbnail of Cognitive Training and Noninvasive Brain Stimulation for Cognition in Parkinson’s Disease: A Meta-analysis

Neurorehabilitation and Neural Repair

Background. Many people with Parkinson's disease (PD) experience cognitive decline. It is not kno... more Background. Many people with Parkinson's disease (PD) experience cognitive decline. It is not known whether cognitive training or noninvasive brain stimulation are effective at alleviating cognitive deficits in PD. Objective. To examine cognitive training and non-invasive brain stimulation interventions for cognition in PD. Methods. An extensive search was conducted of published and unpublished studies in online databases. Studies were selected if they were controlled trials examining standard (not individualized) or tailored (individualized) cognitive training, repetitive transcranial magnetic stimulation (rTMS), or transcranial direct current stimulation (tDCS) in PD, with outcomes measured by standardized neuropsychological tests. Results. Fourteen controlled trials met inclusion criteria. For executive function, the pooled effect size (Hedges' g) for cognitive training (standard and tailored combined) was small (g = 0.42) but statistically significant (95% CI 0.15-0.68). The pooled effect for standard cognitive training (alone) was medium (g = 0.51) and significant (95% CI 0.16-0.85). For attention/working memory, small pooled effect sizes were found when combining standard and tailored cognitive training (g = 0.23; 95% CI 0.02-0.44) and for standard cognitive training alone (g = 0.29; 95% CI 0.04-0.53), both significant. For memory, small but significant pooled effect sizes were also found when combining standard and tailored cognitive training and for standard cognitive training alone. Conclusions. The results suggest that standard and tailored cognitive training may improve executive function, attention/working memory, and memory in PD. Future studies must adopt randomized controlled trial designs to explore the therapeutic potential of these interventions.

Research paper thumbnail of The editors would like to thank the following individuals, who acted as guest-reviewers of manuscripts submitted in 2004

The editors would like to thank the following individuals, who acted as guest-reviewers of manuscripts submitted in 2004

Research paper thumbnail of Mild Cognitive Impairment: Implications of Diagnosis

Mild Cognitive Impairment: Implications of Diagnosis

Journal of Alzheimer’s Disease & Parkinsonism

Research paper thumbnail of Sleep Symptoms Differentially Predict Cognition in Younger and Older-Onset Parkinson's Disease

OBM Geriatrics

Background: Both disrupted sleep and cognitive impairment are frequent in Parkinson's disease (PD... more Background: Both disrupted sleep and cognitive impairment are frequent in Parkinson's disease (PD), but the evidence for a relationship between self-reported sleep disturbance and cognitive symptoms has been equivocal. If sleep symptoms differentially predict cognition in different subtypes, effects may be obscured in a general PD sample. Objective: First, to determine whether the associations between participant and disease variables, sleep symptoms and cognitive performance vary by subtype (younger and olderonset); then to establish whether these effects remain when the sample is reanalysed as a whole. Methods: Multi-group path analyses were used to model the relationships between participant and PD variables; factor scores derived from our bifactor analysis of the Parkinson's Disease Sleep Scale-Revised; and, measures of memory and executive function. Path analyses were replicated as single group analyses. Results: Increased general sleep disturbance predicted better verbal recall in younger-onset PD and poorer visual episodic memory in older-onset PD. Increased insomnia scores predicted better verbal recognition memory in younger-onset PD, better verbal fluency in both groups and poorer spatial working memory (SWM) in older-onset PD. Higher OSA and RBD scores predicted poorer spatial recognition memory and spatial working memory in younger-onset PD, but did not predict cognition in older-onset PD. Many regression coefficients were weakened or reduced to non-significance in the single-sample models. Conclusions: The relationships between participant variables, sleep, and cognition were markedly different in younger and older-onset PD. The influence of sex and premorbid IQ as moderating variables warrant further investigation.

Research paper thumbnail of Cognitive Training and Transcranial Direct Current Stimulation for Mild Cognitive Impairment in Parkinson's Disease: A Randomized Controlled Trial

Parkinson's disease, 2018

This study examined whether standard cognitive training, tailored cognitive training, transcrania... more This study examined whether standard cognitive training, tailored cognitive training, transcranial direct current stimulation (tDCS), standard cognitive training + tDCS, or tailored cognitive training + tDCS improved cognitive function and functional outcomes in participants with PD and mild cognitive impairment (PD-MCI). Forty-two participants with PD-MCI were randomized to one of six groups: (1) standard cognitive training, (2) tailored cognitive training, (3) tDCS, (4) standard cognitive training + tDCS, (5) tailored cognitive training + tDCS, or (6) a control group. Interventions lasted 4 weeks, with cognitive and functional outcomes measured at baseline, post-intervention, and follow-up. The trial was registered with the Australian New Zealand Clinical Trials Registry (ANZCTR: 12614001039673). While controlling for moderator variables, Generalized Linear Mixed Models (GLMMs) showed that when compared to the control group, the intervention groups demonstrated variable statistica...

Research paper thumbnail of The relationship between executive function and fine motor control in young and older adults

The relationship between executive function and fine motor control in young and older adults

Human movement science, Jan 11, 2016

The present study examined the relationship between executive function (EF) and fine motor contro... more The present study examined the relationship between executive function (EF) and fine motor control in young and older healthy adults. Participants completed 3 measures of executive function; a spatial working memory (SWM) task, the Stockings of Cambridge task (planning), and the Intra-Dimensional Extra-Dimensional Set-Shift task (set-shifting). Fine motor control was assessed using 3 subtests of the Purdue Pegboard (unimanual, bimanual, sequencing). For the younger adults, there were no significant correlations between measures of EF and fine motor control. For the older adults, all EFs significantly correlated with all measures of fine motor control. Three separate regressions examined whether planning, SWM and set-shifting independently predicted unimanual, bimanual, and sequencing scores for the older adults. Planning was the primary predictor of performance on all three Purdue subtests. A multiple-groups mediation model examined whether planning predicted fine motor control scor...

Research paper thumbnail of Prevalence and Subtypes of Mild Cognitive Impairment in Parkinson’s Disease

Scientific Reports, 2016

The current study examined the prevalence and subtypes of Mild Cognitive Impairment (MCI) in an A... more The current study examined the prevalence and subtypes of Mild Cognitive Impairment (MCI) in an Australian sample of people with Parkinson's Disease (PD). Seventy participants with PD completed neuropsychological assessments of their cognitive performance, using MDS Task Force Level II diagnostic criteria for PD-MCI. A cutoff score of less than one standard deviation (SD) below normative data determined impaired performance on a neuropsychological test. Of 70 participants, 45 (64%) met Level II diagnostic criteria for PD-MCI. Among those with PD-MCI, 42 (93%) were identified as having multiple domain impairment (28 as amnestic multiple domain and 14 as nonamnestic multiple domain). Single domain impairment was less frequent (2 amnestic/1 nonamnestic). Significant differences were found between the PD-MCI and Normal Cognition groups, across all cognitive domains. Multiple domain cognitive impairment was more frequent than single domain impairment in an Australian sample of people with PD. However, PD-MCI is heterogeneous and current prevalence and subtyping statistics may be an artifact of variable application methods of the criteria (e.g., cut off scores and number of tests). Future longitudinal studies refining the criteria will assist with subtyping the progression of PD-MCI, while identifying individuals who may benefit from pharmacological and nonpharmacological interventions. Parkinson's disease (PD) is now understood as a multifaceted neurodegenerative disorder with heterogeneous motor and non-motor symptoms 1. Approximately 30% of people with PD demonstrate cognitive impairment and up to 50% of those progress to PD-Dementia after more than 10 years of disease duration 2,3. Cognitive impairments in PD comprise four subtypes; amnestic single, amnestic multiple, nonamnestic single and nonamnestic multiple. The four subtypes reflect deficits across five cognitive domains, including: memory, attention/working memory, language, visuospatial, and executive functions 4,5. Several biological and epidemiological risk factors are associated with cognitive deficits in PD, with some studies reporting cognitive impairment is present even at time of diagnosis 6,7. To standardize assessment, the Movement Disorder Society (MDS) Task Force developed new diagnostic criteria for PD-Mild Cognitive Impairment (PD-MCI) 8. Preceding the criteria, most studies adopted the method proposed by Petersen et al. 9 which specifies a decline in memory. PD-MCI is, however, heterogeneous and many people demonstrate impairments across the spectrum of cognitive domains 10. Recent studies adopting the new MDS diagnostic criteria report variable results 11,12. These studies also applied varying diagnostic cut off scores and weighting of tests per cognitive domain, which may influence the reported prevalence of cognitive impairment in PD. The high prevalence and significant impact of cognitive impairment on quality of life for people with PD 13 , indicate that any standardised criteria developed for international use needs to be validated and examined across multiple populations of PD. To date, no study has applied the MDS criteria for PD-MCI to an Australian sample. This study provided a novel application of the MDS Task Force PD-MCI Level II diagnostic criteria to an Australian sample of people with PD. This study also examined PD-MCI frequency differentials at varying diagnostic cut off scores to explore subtype classifications and advance our understanding of cognitive impairments in PD.

Research paper thumbnail of Motor Subtype as a Predictor of Future Working Memory Performance in Idiopathic Parkinson's Disease

PloS one, 2016

Parkinson's disease is a progressive neurodegenerative disorder associated with reduced spati... more Parkinson's disease is a progressive neurodegenerative disorder associated with reduced spatial and verbal working memory ability. There are two established motor subtypes of PD, tremor dominant (TD) and postural instability and gait difficulty (PIGD). This study used structural equation modelling to explore the longitudinal relationship between the two subtypes and working memory assessed at a 2-year follow-up. The study comprised 84 males and 30 females (N = 114), aged between 39 and 85 (M = 64.82, SD = 9.23) with confirmed PD. There was no significant relationship between motor subtype at Time 1 and working memory at Time 2. Postural symptom severity at Time 1 predicted Time 2 spatial working memory for the PIGD subtype (p = .011) but not the TD subtype. Tremor symptoms were not associated with Time 2 working memory in either subtype. Predictive significance of Time 1 postural symptoms only in the PIGD subtype suggests an interaction between symptom dominance (subtype) and sy...

Research paper thumbnail of Psychological Literacy Weakly Differentiates Students by Discipline and Year of Enrolment

Frontiers in psychology, 2016

Psychological literacy, a construct developed to reflect the types of skills graduates of a psych... more Psychological literacy, a construct developed to reflect the types of skills graduates of a psychology degree should possess and be capable of demonstrating, has recently been scrutinized in terms of its measurement adequacy. The recent development of a multi-item measure encompassing the facets of psychological literacy has provided the potential for improved validity in measuring the construct. We investigated the known-groups validity of this multi-item measure of psychological literacy to examine whether psychological literacy could predict (a) students' course of enrolment and (b) students' year of enrolment. Five hundred and fifteen undergraduate psychology students, 87 psychology/human resource management students, and 83 speech pathology students provided data. In the first year cohort, the reflective processes (RPs) factor significantly predicted psychology and psychology/human resource management course enrolment, although no facets significantly differentiated bet...

Research paper thumbnail of Motor control and coordination across the lifespan

Human Movement Science, Oct 1, 2008

in Western Australia, organized the inaugural Motor Control & Human Skill Research Workshop. The ... more in Western Australia, organized the inaugural Motor Control & Human Skill Research Workshop. The primary aim of this original meeting was to bring together researchers investigating the domain of motor control and sensorimotor integration. The 8th Motor Control and Human Skill Conference was held in Fremantle, Western Australia in February of 2007. A selection of the papers presented at this conference make up this special issues of Human Movement Science. At the first meeting in 1991, it was acknowledged that motor control research encompasses many different disciplines and often quite distinct theoretical perspectives. It has resulted in lively debate at many of the conferences in the past, providing insight into the unique contributions that different approaches can provide to our understanding of movement and coordination. This issue contains 13 papers from the conference and is divided into three different sections: (1) Motor Coordination in the Early Years, (2) Ageing and Motor Coordination, and (3) Coordination and Multi-level Control.

Research paper thumbnail of A retrospective assessment of MDS criteria for mild cognitive impairment in Parkinson’s disease

Journal of the International Neuropsychological Society

Objectives: A Movement Disorder Society (MDS) taskforce recently proposed diagnostic criteria for... more Objectives: A Movement Disorder Society (MDS) taskforce recently proposed diagnostic criteria for PD-MCI. This study first examined the prevalence and nature of PD-MCI in a non-demented cohort using the MDS criteria. Using the generic Monte Carlo simulation method developed by Crawford and colleagues (2007), this study then estimated the base rate of the representative population who would demonstrate PD-MCI due to chance alone. Methods: 104 participants with idiopathic PD underwent extensive motor and neuropsychological testing at baseline and 2 years later. The Unified Parkinson’s Disease Rating Scale (UPDRS) was used to assess motor symptoms of PD and a range of established neuropsychological tests were used to assess PD-MCI in accord with MDS criteria. Results: In accord with MDS criteria, 38% of this cohort demonstrated PD-MCI at baseline and 48% at follow-up. Of the 36 participants in the multiple-domain PD-MCI subtype at time-1, 9 (25%) demonstrated no PD-MCI at follow up. An...

Research paper thumbnail of Motor Control and Human Skill

Human Movement Science, 2013

The conference is aimed at examining both theoretical and applied research from disciplines such ... more The conference is aimed at examining both theoretical and applied research from disciplines such as psychology, human movement, physiotherapy, occupational therapy, neurology, and kinesiology. Such a broad range of interests produces many different perspectives to the understanding of the coordination and control of movement. In particular, it provides a forum for the analysis of the diverse theoretical approaches employed in the study of motor control, and the application of these theories to the investigation of such areas as elite performance, motor development and motor disability. Contents The majority of the papers in this series have a developmental theme, with many of the papers focusing on motor disability in childhood. The first paper by Piek and colleagues describes the impact of an intervention program, 'Animal Fun', designed to enhance the motor ability and social skills of 4 to 6 year old children. In their discussion paper, Pannekoek et al. describe a model to explain motivation for physical activity in pre-adolescent children. Rigoli et al. examine the relationship between visual working memory, and fine and gross motor ability in a group of typically developing children and children with Developmental Coordination Disorder. Poor motor performance was also investigated by Chivers et al. who questioned whether a poor performance on some motor skill tests may be confounded by overweight or obesity rather than poor motor competence. In the next paper, Wilson and Hyde investigated how online control develops rapidly in childhood by exploring age-related changes, using a double step reaching task. Age-related changes were also investigated by Smits-Engelsman and Wilson who investigated how the relationship between motor imagery and fine motor control changes with age. A paper by Hands et al. examined the stability of the psychometric

Research paper thumbnail of Does Parkinson's Disease Moderate the Relationship Between Disrupted Sleep and Cognition? A Case-Controlled Polysomnographic Study

Does Parkinson's Disease Moderate the Relationship Between Disrupted Sleep and Cognition? A Case-Controlled Polysomnographic Study

Journal of Sleep Research, 2016

Research paper thumbnail of Cognitive Reserve, Executive Function, and Memory in Parkinson’s Disease

Cognitive impairment is acknowledged as a feature of Parkinson’s disease (PD), and the most commo... more Cognitive impairment is acknowledged as a feature of Parkinson’s disease (PD), and the most common cognitive declines are in executive function (EF) and memory. Cognitive reserve (CR) may offer some protection against cognitive dysfunction in PD. The present study used two proxies of CR (years of education, premorbid IQ) to examine the relationship between CR and (i) EF (ii) memory in a large PD sample (n = 334). Two aspects of EF were examined, including verbal fluency and planning skills. Two aspects of verbal memory were examined, including immediate recall and delayed recall. For EF, both CR proxies significantly predicted verbal fluency, but only years of education predicted planning skills. Years of education significantly predicted immediate recall, but premorbid IQ did not. Neither CR proxy predicted delayed recall. These findings suggest that CR, in particular years of education, may contribute to EF and memory function in those with PD. A key finding of this study is the v...

Research paper thumbnail of doi: 10.3389/fpsyg.2015.00105 The measurement of psychological literacy: a first approximation

doi: 10.3389/fpsyg.2015.00105 The measurement of psychological literacy: a first approximation

Psychological literacy, the ability to apply psychological knowledge to personal, family, occupat... more Psychological literacy, the ability to apply psychological knowledge to personal, family, occupational, community and societal challenges, is promoted as the primary outcome of an undergraduate education in psychology. As the concept of psychological literacy becomes increasingly adopted as the core business of undergraduate psychology training courses world-wide, there is urgent need for the construct to be accurately measured so that student and institutional level progress can be assessed and monitored. Key to the measurement of psychological literacy is determining the underlying factor-structure of psychological literacy. In this paper we provide a first approximation of the measurement of psychological literacy by identifying and evaluating self-report measures for psychological literacy. Multi-item and single-item self-report measures of each of the proposed nine dimensions of psychological literacy were completed by two samples (N = 218 and N = 381) of undergraduate psycholo...

Research paper thumbnail of A Longitudinal Investigation of the Development of Fullterm, Preterm and 'At-Risk' Infants from Birth to Four Years using a Parent Report Measure

A Longitudinal Investigation of the Development of Fullterm, Preterm and 'At-Risk' Infants from Birth to Four Years using a Parent Report Measure

Research paper thumbnail of Motor Heterogeneity in Parkinson's Disease: A Bayesian Perspective

Motor Heterogeneity in Parkinson's Disease: A Bayesian Perspective

Movement Disorders, 2017

Research paper thumbnail of Self-Reported Sleep Differentially Predicts Memory and Executive Function in Younger and Older-Onset Parkinson's Disease

Self-Reported Sleep Differentially Predicts Memory and Executive Function in Younger and Older-Onset Parkinson's Disease

Research paper thumbnail of Measuring General Expectations of Advanced Stage Treatment Outcomes in Parkinson’s Disease

Measuring General Expectations of Advanced Stage Treatment Outcomes in Parkinson’s Disease

Journal of Parkinson's Disease

Background: Recent research suggests that a significant number of those who receive advanced trea... more Background: Recent research suggests that a significant number of those who receive advanced treatments for Parkinson’s disease (PD) do not report improvements for some symptoms, which may relate to their pre-treatment expectations. It is important that expectations of treatment are measured and discussed prior to advanced treatment. Objective: The primary aim of this study was to develop a measure of treatment expectations of two advanced-stage treatments in PD, deep brain stimulation (DBS), and Levodopa/Carbidopa Intestinal Gel (LCIG). A secondary aim was to explore potential predictors of treatment expectations. Methods: The questionnaire-based measure was developed by researchers in conjunction with a highly experienced clinician, and evaluated treatment expectations in 189 people aged 46–91 years (M = 71.35, SD = 8.73; 61% male) with idiopathic PD. Results: The overall measure demonstrated excellent internal consistency (α= 0.96). Exploratory factor analysis suggested the scale...

Research paper thumbnail of Beyond factor analysis: Multidimensionality and the Parkinson’s Disease Sleep Scale-Revised

PLOS ONE, Feb 12, 2018

Many studies have sought to describe the relationship between sleep disturbance and cognition in ... more Many studies have sought to describe the relationship between sleep disturbance and cognition in Parkinson's disease (PD). The Parkinson's Disease Sleep Scale (PDSS) and its variants (the Parkinson's disease Sleep Scale-Revised; PDSS-R, and the Parkinson's Disease Sleep Scale-2; PDSS-2) quantify a range of symptoms impacting sleep in only 15 items. However, data from these scales may be problematic as included items have considerable conceptual breadth, and there may be overlap in the constructs assessed. Multidimensional measurement models, accounting for the tendency for items to measure multiple constructs, may be useful more accurately to model variance than traditional confirmatory factor analysis. In the present study, we tested the hypothesis that a multidimensional model (a bifactor model) is more appropriate than traditional factor analysis for data generated by these types of scales, using data collected using the PDSS-R as an exemplar. 166 participants diagnosed with idiopathic PD participated in this study. Using PDSS-R data, we compared three models: a unidimensional model; a 3-factor model consisting of sub-factors measuring insomnia, motor symptoms and obstructive sleep apnoea (OSA) and REM sleep behaviour disorder (RBD) symptoms; and, a confirmatory bifactor model with both a general factor and the same three sub-factors. Only the confirmatory bifactor model achieved satisfactory model fit, suggesting that PDSS-R data are multidimensional. There were differential associations between factor scores and patient characteristics, suggesting that some PDSS-R items, but not others, are influenced by mood and personality in addition to sleep symptoms. Multidimensional measurement models may also be a helpful tool in the PDSS and the PDSS-2 scales and may improve the sensitivity of these instruments.

Research paper thumbnail of Cognitive Training and Noninvasive Brain Stimulation for Cognition in Parkinson’s Disease: A Meta-analysis

Neurorehabilitation and Neural Repair

Background. Many people with Parkinson's disease (PD) experience cognitive decline. It is not kno... more Background. Many people with Parkinson's disease (PD) experience cognitive decline. It is not known whether cognitive training or noninvasive brain stimulation are effective at alleviating cognitive deficits in PD. Objective. To examine cognitive training and non-invasive brain stimulation interventions for cognition in PD. Methods. An extensive search was conducted of published and unpublished studies in online databases. Studies were selected if they were controlled trials examining standard (not individualized) or tailored (individualized) cognitive training, repetitive transcranial magnetic stimulation (rTMS), or transcranial direct current stimulation (tDCS) in PD, with outcomes measured by standardized neuropsychological tests. Results. Fourteen controlled trials met inclusion criteria. For executive function, the pooled effect size (Hedges' g) for cognitive training (standard and tailored combined) was small (g = 0.42) but statistically significant (95% CI 0.15-0.68). The pooled effect for standard cognitive training (alone) was medium (g = 0.51) and significant (95% CI 0.16-0.85). For attention/working memory, small pooled effect sizes were found when combining standard and tailored cognitive training (g = 0.23; 95% CI 0.02-0.44) and for standard cognitive training alone (g = 0.29; 95% CI 0.04-0.53), both significant. For memory, small but significant pooled effect sizes were also found when combining standard and tailored cognitive training and for standard cognitive training alone. Conclusions. The results suggest that standard and tailored cognitive training may improve executive function, attention/working memory, and memory in PD. Future studies must adopt randomized controlled trial designs to explore the therapeutic potential of these interventions.

Research paper thumbnail of The editors would like to thank the following individuals, who acted as guest-reviewers of manuscripts submitted in 2004

The editors would like to thank the following individuals, who acted as guest-reviewers of manuscripts submitted in 2004

Research paper thumbnail of Mild Cognitive Impairment: Implications of Diagnosis

Mild Cognitive Impairment: Implications of Diagnosis

Journal of Alzheimer’s Disease & Parkinsonism

Research paper thumbnail of Sleep Symptoms Differentially Predict Cognition in Younger and Older-Onset Parkinson's Disease

OBM Geriatrics

Background: Both disrupted sleep and cognitive impairment are frequent in Parkinson's disease (PD... more Background: Both disrupted sleep and cognitive impairment are frequent in Parkinson's disease (PD), but the evidence for a relationship between self-reported sleep disturbance and cognitive symptoms has been equivocal. If sleep symptoms differentially predict cognition in different subtypes, effects may be obscured in a general PD sample. Objective: First, to determine whether the associations between participant and disease variables, sleep symptoms and cognitive performance vary by subtype (younger and olderonset); then to establish whether these effects remain when the sample is reanalysed as a whole. Methods: Multi-group path analyses were used to model the relationships between participant and PD variables; factor scores derived from our bifactor analysis of the Parkinson's Disease Sleep Scale-Revised; and, measures of memory and executive function. Path analyses were replicated as single group analyses. Results: Increased general sleep disturbance predicted better verbal recall in younger-onset PD and poorer visual episodic memory in older-onset PD. Increased insomnia scores predicted better verbal recognition memory in younger-onset PD, better verbal fluency in both groups and poorer spatial working memory (SWM) in older-onset PD. Higher OSA and RBD scores predicted poorer spatial recognition memory and spatial working memory in younger-onset PD, but did not predict cognition in older-onset PD. Many regression coefficients were weakened or reduced to non-significance in the single-sample models. Conclusions: The relationships between participant variables, sleep, and cognition were markedly different in younger and older-onset PD. The influence of sex and premorbid IQ as moderating variables warrant further investigation.

Research paper thumbnail of Cognitive Training and Transcranial Direct Current Stimulation for Mild Cognitive Impairment in Parkinson's Disease: A Randomized Controlled Trial

Parkinson's disease, 2018

This study examined whether standard cognitive training, tailored cognitive training, transcrania... more This study examined whether standard cognitive training, tailored cognitive training, transcranial direct current stimulation (tDCS), standard cognitive training + tDCS, or tailored cognitive training + tDCS improved cognitive function and functional outcomes in participants with PD and mild cognitive impairment (PD-MCI). Forty-two participants with PD-MCI were randomized to one of six groups: (1) standard cognitive training, (2) tailored cognitive training, (3) tDCS, (4) standard cognitive training + tDCS, (5) tailored cognitive training + tDCS, or (6) a control group. Interventions lasted 4 weeks, with cognitive and functional outcomes measured at baseline, post-intervention, and follow-up. The trial was registered with the Australian New Zealand Clinical Trials Registry (ANZCTR: 12614001039673). While controlling for moderator variables, Generalized Linear Mixed Models (GLMMs) showed that when compared to the control group, the intervention groups demonstrated variable statistica...

Research paper thumbnail of The relationship between executive function and fine motor control in young and older adults

The relationship between executive function and fine motor control in young and older adults

Human movement science, Jan 11, 2016

The present study examined the relationship between executive function (EF) and fine motor contro... more The present study examined the relationship between executive function (EF) and fine motor control in young and older healthy adults. Participants completed 3 measures of executive function; a spatial working memory (SWM) task, the Stockings of Cambridge task (planning), and the Intra-Dimensional Extra-Dimensional Set-Shift task (set-shifting). Fine motor control was assessed using 3 subtests of the Purdue Pegboard (unimanual, bimanual, sequencing). For the younger adults, there were no significant correlations between measures of EF and fine motor control. For the older adults, all EFs significantly correlated with all measures of fine motor control. Three separate regressions examined whether planning, SWM and set-shifting independently predicted unimanual, bimanual, and sequencing scores for the older adults. Planning was the primary predictor of performance on all three Purdue subtests. A multiple-groups mediation model examined whether planning predicted fine motor control scor...

Research paper thumbnail of Prevalence and Subtypes of Mild Cognitive Impairment in Parkinson’s Disease

Scientific Reports, 2016

The current study examined the prevalence and subtypes of Mild Cognitive Impairment (MCI) in an A... more The current study examined the prevalence and subtypes of Mild Cognitive Impairment (MCI) in an Australian sample of people with Parkinson's Disease (PD). Seventy participants with PD completed neuropsychological assessments of their cognitive performance, using MDS Task Force Level II diagnostic criteria for PD-MCI. A cutoff score of less than one standard deviation (SD) below normative data determined impaired performance on a neuropsychological test. Of 70 participants, 45 (64%) met Level II diagnostic criteria for PD-MCI. Among those with PD-MCI, 42 (93%) were identified as having multiple domain impairment (28 as amnestic multiple domain and 14 as nonamnestic multiple domain). Single domain impairment was less frequent (2 amnestic/1 nonamnestic). Significant differences were found between the PD-MCI and Normal Cognition groups, across all cognitive domains. Multiple domain cognitive impairment was more frequent than single domain impairment in an Australian sample of people with PD. However, PD-MCI is heterogeneous and current prevalence and subtyping statistics may be an artifact of variable application methods of the criteria (e.g., cut off scores and number of tests). Future longitudinal studies refining the criteria will assist with subtyping the progression of PD-MCI, while identifying individuals who may benefit from pharmacological and nonpharmacological interventions. Parkinson's disease (PD) is now understood as a multifaceted neurodegenerative disorder with heterogeneous motor and non-motor symptoms 1. Approximately 30% of people with PD demonstrate cognitive impairment and up to 50% of those progress to PD-Dementia after more than 10 years of disease duration 2,3. Cognitive impairments in PD comprise four subtypes; amnestic single, amnestic multiple, nonamnestic single and nonamnestic multiple. The four subtypes reflect deficits across five cognitive domains, including: memory, attention/working memory, language, visuospatial, and executive functions 4,5. Several biological and epidemiological risk factors are associated with cognitive deficits in PD, with some studies reporting cognitive impairment is present even at time of diagnosis 6,7. To standardize assessment, the Movement Disorder Society (MDS) Task Force developed new diagnostic criteria for PD-Mild Cognitive Impairment (PD-MCI) 8. Preceding the criteria, most studies adopted the method proposed by Petersen et al. 9 which specifies a decline in memory. PD-MCI is, however, heterogeneous and many people demonstrate impairments across the spectrum of cognitive domains 10. Recent studies adopting the new MDS diagnostic criteria report variable results 11,12. These studies also applied varying diagnostic cut off scores and weighting of tests per cognitive domain, which may influence the reported prevalence of cognitive impairment in PD. The high prevalence and significant impact of cognitive impairment on quality of life for people with PD 13 , indicate that any standardised criteria developed for international use needs to be validated and examined across multiple populations of PD. To date, no study has applied the MDS criteria for PD-MCI to an Australian sample. This study provided a novel application of the MDS Task Force PD-MCI Level II diagnostic criteria to an Australian sample of people with PD. This study also examined PD-MCI frequency differentials at varying diagnostic cut off scores to explore subtype classifications and advance our understanding of cognitive impairments in PD.

Research paper thumbnail of Motor Subtype as a Predictor of Future Working Memory Performance in Idiopathic Parkinson's Disease

PloS one, 2016

Parkinson's disease is a progressive neurodegenerative disorder associated with reduced spati... more Parkinson's disease is a progressive neurodegenerative disorder associated with reduced spatial and verbal working memory ability. There are two established motor subtypes of PD, tremor dominant (TD) and postural instability and gait difficulty (PIGD). This study used structural equation modelling to explore the longitudinal relationship between the two subtypes and working memory assessed at a 2-year follow-up. The study comprised 84 males and 30 females (N = 114), aged between 39 and 85 (M = 64.82, SD = 9.23) with confirmed PD. There was no significant relationship between motor subtype at Time 1 and working memory at Time 2. Postural symptom severity at Time 1 predicted Time 2 spatial working memory for the PIGD subtype (p = .011) but not the TD subtype. Tremor symptoms were not associated with Time 2 working memory in either subtype. Predictive significance of Time 1 postural symptoms only in the PIGD subtype suggests an interaction between symptom dominance (subtype) and sy...

Research paper thumbnail of Psychological Literacy Weakly Differentiates Students by Discipline and Year of Enrolment

Frontiers in psychology, 2016

Psychological literacy, a construct developed to reflect the types of skills graduates of a psych... more Psychological literacy, a construct developed to reflect the types of skills graduates of a psychology degree should possess and be capable of demonstrating, has recently been scrutinized in terms of its measurement adequacy. The recent development of a multi-item measure encompassing the facets of psychological literacy has provided the potential for improved validity in measuring the construct. We investigated the known-groups validity of this multi-item measure of psychological literacy to examine whether psychological literacy could predict (a) students' course of enrolment and (b) students' year of enrolment. Five hundred and fifteen undergraduate psychology students, 87 psychology/human resource management students, and 83 speech pathology students provided data. In the first year cohort, the reflective processes (RPs) factor significantly predicted psychology and psychology/human resource management course enrolment, although no facets significantly differentiated bet...

Research paper thumbnail of Motor control and coordination across the lifespan

Human Movement Science, Oct 1, 2008

in Western Australia, organized the inaugural Motor Control & Human Skill Research Workshop. The ... more in Western Australia, organized the inaugural Motor Control & Human Skill Research Workshop. The primary aim of this original meeting was to bring together researchers investigating the domain of motor control and sensorimotor integration. The 8th Motor Control and Human Skill Conference was held in Fremantle, Western Australia in February of 2007. A selection of the papers presented at this conference make up this special issues of Human Movement Science. At the first meeting in 1991, it was acknowledged that motor control research encompasses many different disciplines and often quite distinct theoretical perspectives. It has resulted in lively debate at many of the conferences in the past, providing insight into the unique contributions that different approaches can provide to our understanding of movement and coordination. This issue contains 13 papers from the conference and is divided into three different sections: (1) Motor Coordination in the Early Years, (2) Ageing and Motor Coordination, and (3) Coordination and Multi-level Control.

Research paper thumbnail of A retrospective assessment of MDS criteria for mild cognitive impairment in Parkinson’s disease

Journal of the International Neuropsychological Society

Objectives: A Movement Disorder Society (MDS) taskforce recently proposed diagnostic criteria for... more Objectives: A Movement Disorder Society (MDS) taskforce recently proposed diagnostic criteria for PD-MCI. This study first examined the prevalence and nature of PD-MCI in a non-demented cohort using the MDS criteria. Using the generic Monte Carlo simulation method developed by Crawford and colleagues (2007), this study then estimated the base rate of the representative population who would demonstrate PD-MCI due to chance alone. Methods: 104 participants with idiopathic PD underwent extensive motor and neuropsychological testing at baseline and 2 years later. The Unified Parkinson’s Disease Rating Scale (UPDRS) was used to assess motor symptoms of PD and a range of established neuropsychological tests were used to assess PD-MCI in accord with MDS criteria. Results: In accord with MDS criteria, 38% of this cohort demonstrated PD-MCI at baseline and 48% at follow-up. Of the 36 participants in the multiple-domain PD-MCI subtype at time-1, 9 (25%) demonstrated no PD-MCI at follow up. An...

Research paper thumbnail of Motor Control and Human Skill

Human Movement Science, 2013

The conference is aimed at examining both theoretical and applied research from disciplines such ... more The conference is aimed at examining both theoretical and applied research from disciplines such as psychology, human movement, physiotherapy, occupational therapy, neurology, and kinesiology. Such a broad range of interests produces many different perspectives to the understanding of the coordination and control of movement. In particular, it provides a forum for the analysis of the diverse theoretical approaches employed in the study of motor control, and the application of these theories to the investigation of such areas as elite performance, motor development and motor disability. Contents The majority of the papers in this series have a developmental theme, with many of the papers focusing on motor disability in childhood. The first paper by Piek and colleagues describes the impact of an intervention program, 'Animal Fun', designed to enhance the motor ability and social skills of 4 to 6 year old children. In their discussion paper, Pannekoek et al. describe a model to explain motivation for physical activity in pre-adolescent children. Rigoli et al. examine the relationship between visual working memory, and fine and gross motor ability in a group of typically developing children and children with Developmental Coordination Disorder. Poor motor performance was also investigated by Chivers et al. who questioned whether a poor performance on some motor skill tests may be confounded by overweight or obesity rather than poor motor competence. In the next paper, Wilson and Hyde investigated how online control develops rapidly in childhood by exploring age-related changes, using a double step reaching task. Age-related changes were also investigated by Smits-Engelsman and Wilson who investigated how the relationship between motor imagery and fine motor control changes with age. A paper by Hands et al. examined the stability of the psychometric