Francesco Carletti | King's College London (original) (raw)

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Papers by Francesco Carletti

Schizophrenia Research, 2015

Background: Individuals with an "Attenuated Psychosis Syndrome" (APS) have a 20-40% chance of dev... more Background: Individuals with an "Attenuated Psychosis Syndrome" (APS) have a 20-40% chance of developing a psychotic disorder within two years; however it is difficult to predict which of them will become ill on the basis of their clinical symptoms alone. We examined whether P50 gating deficits could help to discriminate individuals with APS and also those who are particularly likely to make a transition to psychosis. Method: 36 cases meeting PACE (Personal Assessment and Crisis Evaluation) criteria for the APS, all free of antipsychotics, and 60 controls performed an auditory conditioning-testing experiment while their electroencephalogram was recorded. The P50 ratio and its C-T difference were compared between groups. Subjects received follow-up for up to 2 years to determine their clinical outcome. Results: The P50 ratio was significantly higher and C-T difference lower in the APS group compared to controls. Of the individuals with APS who completed the follow-up (n = 36), nine (25%) developed psychosis. P50 ratio and the C-T difference did not significantly differ between those individuals who developed psychosis and those who did not within the APS group. Conclusion: P50 deficits appear to be associated with the pre-clinical phase of psychosis. However, due to the limitations of the study and its sample size, replication in an independent cohort is necessary, to clarify the role of P50 deficits in illness progression and whether this inexpensive and non-invasive EEG marker could be of clinical value in the prediction of psychosis outcomes amongst populations at risk.

Background Most of our social interactions involve perception of emotional information from the f... more Background Most of our social interactions involve perception of emotional information from the faces of other people. Furthermore, such emotional processes are thought to be aberrant in a range of clinical disorders, including psychosis and depression. However, the exact neurofunctional maps underlying emotional facial processing are not well defined.

Participants: A total of 62 subjects, comprising 32 UHR and 30 matched healthy controls (HC) were... more Participants: A total of 62 subjects, comprising 32 UHR and 30 matched healthy controls (HC) were recruited for the study. After a mean period of 24 months, 8 (25%) of the UHR subjects had developed psychosis (UHR-P) while 24 (75%) had not (UHR-NP).

Background Psychosis onset is characterized by white matter and electrophysiologic abnormalities.... more Background Psychosis onset is characterized by white matter and electrophysiologic abnormalities. The relation between these factors in the development of illness is almost unknown. We studied the relation between white matter volumes and P300 in prodromal psychosis.

Schizophrenia bulletin, Jan 1, 2012

Background: Psychotic disorders are associated with widespread reductions in white matter (WM) in... more Background: Psychotic disorders are associated with widespread reductions in white matter (WM) integrity. However, the stage at which these abnormalities first appear and whether they are correlates of psychotic illness, as opposed to an increased vulnerability to psychosis, is unclear. We addressed these issues by using diffusion tensor imaging (DTI) to study subjects at ultra high risk (UHR) of psychosis before and after the onset of illness. Methods: Thirty-two individuals at UHR for psychosis, 32 controls, and 15 patients with first-episode schizophrenia were studied using DTI. The UHR subjects and controls were re-scanned after 28 months. During this period, 8 UHR subjects had developed schizophrenia. Between-group differences in fractional anisotropy (FA) and diffusivity were evaluated cross sectionally and longitudinally using a nonparametric voxel-based analysis. Results: At baseline, WM DTI properties were significantly different between the 3 groups (P < .001). Relative to controls, first-episode patients showed widespread reductions in FA and increases in diffusivity. DTI indices in the UHR group were intermediate relative to those in the other 2 groups. Longitudinal analysis revealed a significant group by time interaction in the left frontal WM (P < .001). In this region, there was a progressive reduction in FA in UHR subjects who developed psychosis that was not evident in UHR subjects who did not make a transition. Conclusions: People at UHR for psychosis show alterations in WM qualitatively similar to, but less severe than, those in patients with schizophrenia. The onset of schizophrenia may be associated with a progressive reduction in the integrity of the frontal WM.

European Psychiatry, Jan 1, 2010

DTI studies in schizophrenia have consistently reported decreased fractional anisotropy (FA, an i... more DTI studies in schizophrenia have consistently reported decreased fractional anisotropy (FA, an index of white matter microstructure) in patients. There is little evidence as to the genetic or environmental determinants of this difference however. Studies of twins with schizophrenia allow us to estimate these influences. We report a cross-sectional case control study of twins with and without schizophrenia.We recruited mono- and di-zygotic twins concordant and discordant for DSM schizophrenia from across the United Kingdom, referred by their treating psychiatrists. We recruited healthy control twins from the Institute of Psychiatry Volunteer Twin Register and by national media advertisements. Clinical diagnoses were confirmed using the Schedule for Affective Disorders and Schizophrenia-Lifetime Version (Spitzer and Endicott, 1978). Zygosity was confirmed by DNA analysis. Eleven pairs of monozygotic twins concordant for schizophrenia, 10 pairs of monozygotic and seven pairs of dizygotic twins discordant for schizophrenia, 24 pairs of healthy monozygotic twins and 20 pairs of healthy dizygotic twins were recruited.Subjects were scanned with an optimized DTI sequence at 1.5T. Scans were warp-corrected, masked, and FA calculated at each voxel. FA maps were then co-registered to a study-specific FA template using SPM2 and group differences calculated on segmented white-matter FA maps using non-parametric XBAM_v3.4.Results are presented of analyses comparing twins with schizophrenia with their well co-twin, linear trend analyses comparing healthy controls with well di and mono-zygotic co-twins, and a heritability analysis of the healthy controls.

Schizophrenia Research, Jan 1, 2010

Schizophrenia Research, Volume 117, Issue 2, Pages 462, April 2010, Authors:Francesco Carletti; J... more Schizophrenia Research, Volume 117, Issue 2, Pages 462, April 2010, Authors:Francesco Carletti; James Woolley; Matthew Broome; Elvira Bramon; Louise Johns; Paolo Fusar Poli; Lucia Valmaggia; Vincent Giampietro; Gareth J. Barker; Philip K. McGuire.

Neuroimage, Jan 1, 2011

Psychotic disorders are characterized by gray matter and volumetric and electrophysiological abno... more Psychotic disorders are characterized by gray matter and volumetric and electrophysiological abnormalities. The relationship between these factors in the onset of psychotic illness is unclear.Eighty English-native right-handed subjects (39 subjects at ultra high risk for psychosis “ARMS” and 41 healthy volunteers) were scanned with MRI, and studied using EEG during an oddball task. Both assessments were performed at first clinical presentation. The ARMS subjects were then followed clinically, with the MRI and EEG assessments repeated in a subgroup of each sample.The P300 amplitude at presentation was significantly lower in the ARMS subjects than in controls. At baseline, the ARMS group showed reduced gray matter volume relative to controls in the right superior frontal gyrus, left medial frontal gyrus, left inferior frontal gyrus, right orbital gyrus and right supramarginal gyrus. Transition to psychosis (26%) was associated with reduced gray matter in the right inferior parietal lobule and in the left parahippocampal gyrus. Within the ARMS group, there was a positive correlation between P300 amplitude and gray matter volume in the right supramarginal gyrus. A significant group by P300 by gray matter interaction was detected in the left medial frontal gyrus. Longitudinal assessment revealed progressive gray matter alterations in prefrontal and subcortical areas of the ARMS but no significant changes in P300 amplitude over time.P300 abnormalities in the ARMS are related to alterations in regional gray matter volume and represent a correlate of an increased vulnerability to psychosis.► P300 amplitude is lower in subjects at high risk for psychosis than in controls. ► High risk subjects show reduced frontal and temporo-parietal gray matter volume. ► P300 abnormalities in high risk subjects are related to gray matter alterations. ► In future it may be possible to use multimodal neuroimaging to predict psychosis.

$Research paper thumbnail of Reduced fractional anisotropy of corpus callosum in first-contact, antipsychotic drug-naive patients with schizophrenia$

Schizophrenia Research, Jan 1, 2009

Background: Corpus callosum is the most important commissure of the brain and therefore represent... more Background: Corpus callosum is the most important commissure of the brain and therefore represents a first-choice candidate to challenge hypotheses of disrupted inter-hemispheric connectivity and white matter pathology in patients with schizophrenia. Recent studies on diffusion tensor imaging (DTI) of corpus callosum yielded promising but equivocal evidence of reduced fractional anisotropy (FA) in schizophrenia patients who were, for the most part, chronic cases on medication for a lengthy period of time. To exclude potentially confounding effects of the course of the disorder and its treatment, we compared callosal FA of first-contact, antipsychotic drug-naive schizophrenia patients (n = 21) and healthy controls (n = 21).

Neuroscience Letters, Jan 1, 2009

Recognizing emotion from facial expressions draws on diverse psychological processes implemented ... more Recognizing emotion from facial expressions draws on diverse psychological processes implemented in a large array of neural structures. Two major theories of cerebral lateralization of emotional perception have been proposed: (i) the Right-Hemisphere Hypothesis (RHH) and (ii) the Valence-Specific Hypothesis (VSH). To test these lateralization models we conducted a large voxel-based meta-analysis of current functional magnetic resonance imaging (fMRI) studies employing emotional faces paradigms in healthy volunteers. Two independent researchers conducted separate comprehensive PUBMED (1990–May 2008) searches to find all functional magnetic resonance imaging studies using a variant of the emotional faces paradigm in healthy subjects. Out of the 551 originally identified studies, 105 studies met inclusion criteria. The overall database consisted of 1785 brain coordinates which yield an overall sample of 1600 healthy subjects. We found no support for the hypothesis of overall right-lateralization of emotional processing. Conversely, across all emotional conditions the parahippocampal gyrus and amygdala, fusiform gyrus, lingual gyrus, precuneus, inferior and middle occipital gyrus, posterior cingulated, middle temporal gyrus, inferior frontal and superior frontal gyri were activated bilaterally (p = 0.001). There was a valence-specific lateralization of brain response during negative emotions processing in the left amygdala (p = 0.001). Significant interactions between the approach and avoidance dimensions and prefrontal response were observed (p = 0.001).