Melissa Garcia | Universidad Pedagógica Nacional, México (original) (raw)

Papers by Melissa Garcia

In anticipation of the sequencing of the human genome and description of the human proteome, the ... more In anticipation of the sequencing of the human genome and description of the human proteome, the Age, Gene/ Environment Susceptibility-Reykjavik Study (AGES-Reykjavik) was initiated in 2002. AGES-Reykjavik was designed to examine risk factors, including genetic susceptibility and gene/environment interaction, in relation to disease and disability in old age. The study is multidisciplinary, providing detailed phenotypes related to the cardiovascular, neurocognitive (including sensory), and musculoskeletal systems, and to body composition and metabolic regulation. Relevant quantitative traits, subclinical indicators of disease, and medical diagnoses are identified by using biomarkers, imaging, and other physiologic indicators. The AGES-Reykjavik sample is drawn from an established population-based cohort, the Reykjavik Study. This cohort of men and women born between 1907 and 1935 has been followed in Iceland since 1967 by the Icelandic Heart Association. The AGES-Reykjavik cohort, with cardiovascular risk factor assessments earlier in life and detailed late-life phenotypes of quantitative traits, will create a comprehensive study of aging nested in a relatively genetically homogeneous older population. This approach should facilitate identification of genetic factors that contribute to healthy aging as well as the chronic conditions common in old age.

Annals of Epidemiology, 2006

We assessed the accuracy and reliability of maternal recall of infant birth weight 35 to 70 years... more We assessed the accuracy and reliability of maternal recall of infant birth weight 35 to 70 years after delivery. METHODS: A total of 120 well functioning women (mean age 80 years; 45% Black) reported the birth weight for each live birth and then provided documentation of birth weights (n Z 22) or reported birth weights a second time (n Z 98). RESULTS: Agreement between recalled and documented birth weights was high for first births (ICC Z 0.96) but moderate for subsequent births (ICC Z 0.59). Maternal recall was highly reliable for first births (r Z 0.95) and subsequent births (r Z 0.87), and reliability remained high when considered separately by race, education, income, and age. CONCLUSION: Women report accurate and reliable infant birth-weight data an average of 57 years after delivery, and recall is particularly precise for first births.

Stroke, 2009

Background & Purpose-Cerebral infarcts increase the risk for cognitive impairment. The relevance ... more Background & Purpose-Cerebral infarcts increase the risk for cognitive impairment. The relevance of location and number of infarcts with respect to cognitive function is less clear.

Neurobiology of Aging, 2010

Objective: To assess whether markers of micro-and macro-structural brain abnormalities are associ... more Objective: To assess whether markers of micro-and macro-structural brain abnormalities are associated with slower gait in older men and women independent of each other, and also independent of health-related conditions and of behavioral, cognitive and peripheral function.

OBJECTIVES: To examine dog walking among dog owners and the relationship between walking behavior... more OBJECTIVES: To examine dog walking among dog owners and the relationship between walking behavior of dog owners and non-dog owners and maintained gait speed over 3 years. DESIGN: Cross-sectional and longitudinal analyses of a prospective cohort study. SETTING: Memphis, Tennessee, and Pittsburgh, Pennsylvania. PARTICIPANTS: Two thousand five hundred thirty-three community-dwelling adults aged 71 to 82 at 36 months of the Health, Aging and Body Composition Study. MEASUREMENTS: Dog ownership, reported walking behavior, change in walking behavior, and usual and rapid gait speed over 3 years. RESULTS: Of 394 dog owners, only 36% walked their dogs at least three times per week. Cross-sectionally, dog walkers were more likely to achieve 150 minutes of walking per week and had faster usual and rapid walking speeds (1.20 vs 1.14 m/s and 1.62 vs 1.52 m/s, respectively; Po.01 for both) than non-dog owners who did not walk at least three times per week and similar speeds as non-dog owners who walked at least 150 minutes per week (P4.50). Three years later, subjects who had been dog walkers at baseline were approximately twice as likely as any other group to achieve recommended walking levels, independent of covariates. Dog walkers experienced similar declines in usual and rapid walking speed as non-dog owners who walked at least three times per week but maintained their initial mobility advantage. CONCLUSION: Although dog ownership appears to facilitate walking behavior, only a minority of older dog owners walk their dogs. The mobility advantage of dog ownership was seen only in dog walkers and was similar to that associated with any walking. Given suboptimal walking activity in older adults, examining the degree to which dog ownership promotes walking activity in persons who do little walking on their own appears worth pursuing.

Background. Among persons with white matter lesions (WMLs), there is a range of cognitive functio... more Background. Among persons with white matter lesions (WMLs), there is a range of cognitive function. We examine whether participation in leisure activities modifies the effect of WML load on cognitive function.

Journal of The American Geriatrics Society, 2007

OBJECTIVES: To test the hypothesis that increased long-term mortality after hospitalization for c... more OBJECTIVES: To test the hypothesis that increased long-term mortality after hospitalization for community-acquired pneumonia (CAP) is independent of comorbid conditions.DESIGN: Prospective observational cohort study in metropolitan areas.SETTING: Memphis, Tennessee, and Pittsburgh, Pennsylvania.PARTICIPANTS: Three thousand seventy-five subjects aged 70 to 79 over 5.2 years.MEASUREMENTS: Unadjusted and adjusted mortality from an initial hospitalization for CAP were compared with mortality from different causes of hospitalization, including cancer, fracture, congestive heart failure (CHF), cerebrovascular accident (CVA), and other causes. Demographics, smoking, nutritional markers, functional status, inflammatory markers, and chronic health conditions were adjusted for.RESULTS: Of the 106 subjects hospitalized for CAP, 22 (20.8%) and 38 (35.8%) died at 1 and 5 years. Subjects hospitalized with CAP had higher mortality than nonhospitalized subjects (adjusted odds ratio (OR)=7.8, 95% confidence interval (CI)=4.2–14.4). One- and 5-year mortality after CAP hospitalization were higher than mortality from other causes requiring hospitalization and remained unchanged in multivariable analysis (adjusted OR=3.5, 95% CI=1.5–8.1; adjusted OR=5.6, 95% CI=2.8–11.2, respectively). One- and 5-year mortality after hospitalization for CAP were similar to or higher than mortality after an initial hospitalization for CHF, CVA, or fracture. Rehospitalization was common in subjects hospitalized for CAP and may explain greater long-term mortality.CONCLUSION: In this high-functioning cohort of older persons, an initial hospitalization for CAP was associated with greater long-term mortality, independent of prehospitalization comorbid conditions. Hospitalization for CAP has as serious a prognosis as hospitalization for CHF, stroke, or major fracture.

Persons with type 2 diabetes are at increased risk of cognitive dysfunction. Less is known about ... more Persons with type 2 diabetes are at increased risk of cognitive dysfunction. Less is known about which cognitive abilities are affected and how undiagnosed diabetes and impaired fasting glucose relate to cognitive performance. The authors explored this question using data from 1,917 nondemented men and women (average age ¼ 76 years) in the population-based Age, Gene/Environment Susceptibility-Reykjavik Study (2002)(2003)(2004)(2005)(2006). Glycemic status groups included diagnosed diabetes (self-reported diabetes or diabetic medication use; n ¼ 163 (8.5%)), undiagnosed diabetes (fasting blood glucose !7.0 mmol/L without diagnosed diabetes; n ¼ 55 (2.9%)), and impaired fasting glucose (fasting blood glucose 5.6-6.9 mmol/L; n ¼ 744 (38.8%)). Composites of memory, processing speed (PS), and executive function were constructed from a neuropsychological battery. Linear regression was used to investigate cross-sectional differences in cognitive performance between glycemic groups, adjusted for demographic and health factors. Persons with diagnosed diabetes had slower PS than normoglycemics (b ¼ À0.12; P < 0.05); diabetes duration of !15 years was associated with significantly poorer PS and executive function. Undiagnosed diabetics had slower PS (b ¼ À0.22; P < 0.01) and poorer memory performance (b ¼ À0.22; P < 0.05). Persons with type 2 diabetes have poorer cognitive performance than normoglycemics, particularly in PS. Those with undiagnosed diabetes have the lowest cognitive performance.

American Journal of Human Genetics, 2008

White blood cell count (WBC) is an important clinical marker that varies among different ethnic g... more White blood cell count (WBC) is an important clinical marker that varies among different ethnic groups. African Americans are known to have a lower WBC than European Americans. We surveyed the entire genome for loci underlying this difference in WBC by using admixture mapping. We analyzed data from African American participants in the Health, Aging, and Body Composition Study and the Jackson Heart Study. Participants of both studies were genotyped across R 1322 single nucleotide polymorphisms that were preselected to be informative for African versus European ancestry and span the entire genome. We used these markers to estimate genetic ancestry in each chromosomal region and then tested the association between WBC and genetic ancestry at each locus. We found a locus on chromosome 1q strongly associated with WBC (p < 10 À12 ). The strongest association was with a marker known to affect the expression of the Duffy blood group antigen. Participants who had both copies of the common West African allele had a mean WBC of 4.9 (SD 1.3); participants who had both common European alleles had a mean WBC of 7.1 (SD 1.3). This variant explained~20% of population variation in WBC. We used admixture mapping, a novel method for conducting genetic-association studies, to find a region that was significantly associated with WBC on chromosome 1q. Additional studies are needed to determine the biological mechanism for this effect and its clinical implications.

Diabetes increases the risk for microvascular disease. The retina and the brain both have intrica... more Diabetes increases the risk for microvascular disease. The retina and the brain both have intricate microvascular systems that are developmentally similar. We sought to examine whether microvascular lesions in the retina and in the brain are associated and whether this association differs among people with and without diabetes. The analysis included 4,218 participants of the Icelandic population-based Age, Gene/Environment Susceptibility-Reykjavik Study who were born in 1907-1935 and who were previously followed as a part of the Reykjavik Study. Retinal focal arteriolar narrowing, arteriovenous (AV) nicking, and microaneurysms/hemorrhages were evaluated on digital retinal images of both eyes. Cerebral microbleeds (CMBs) were evaluated from magnetic resonance images. Data were analyzed with logistic and multinomial logistic regression models controlling for demographics, major cardiovascular risk factors, cerebral infarcts, and white matter lesions. Evidence of brain microbleeds was found in 485 (11.5%) people, including 192 with multiple (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;or=2) microbleeds. Subjects with signs of retinal microvascular lesions were at a significantly increased likelihood for having multiple CMBs. People with diabetes in combination with the presence of either retinal AV nicking (odds ratio [OR] 2.47 [95% CI 1.42-4.31]) or retinal microaneurysms/hemorrhages (2.28 [1.24-4.18]) were significantly more likely to have multiple CMBs. Retinal microvascular abnormalities and brain microbleeds may occur together in older adults. People with both diabetes and signs of retinal microvascular lesions (AV nicking and microaneurysms/hemorrhages) are more likely to have multiple microbleeds in the brain. Microvascular disease in diabetes extends to the brain.

In anticipation of the sequencing of the human genome and description of the human proteome, the ... more In anticipation of the sequencing of the human genome and description of the human proteome, the Age, Gene/ Environment Susceptibility-Reykjavik Study (AGES-Reykjavik) was initiated in 2002. AGES-Reykjavik was designed to examine risk factors, including genetic susceptibility and gene/environment interaction, in relation to disease and disability in old age. The study is multidisciplinary, providing detailed phenotypes related to the cardiovascular, neurocognitive (including sensory), and musculoskeletal systems, and to body composition and metabolic regulation. Relevant quantitative traits, subclinical indicators of disease, and medical diagnoses are identified by using biomarkers, imaging, and other physiologic indicators. The AGES-Reykjavik sample is drawn from an established population-based cohort, the Reykjavik Study. This cohort of men and women born between 1907 and 1935 has been followed in Iceland since 1967 by the Icelandic Heart Association. The AGES-Reykjavik cohort, with cardiovascular risk factor assessments earlier in life and detailed late-life phenotypes of quantitative traits, will create a comprehensive study of aging nested in a relatively genetically homogeneous older population. This approach should facilitate identification of genetic factors that contribute to healthy aging as well as the chronic conditions common in old age.

Annals of Epidemiology, 2006

We assessed the accuracy and reliability of maternal recall of infant birth weight 35 to 70 years... more We assessed the accuracy and reliability of maternal recall of infant birth weight 35 to 70 years after delivery. METHODS: A total of 120 well functioning women (mean age 80 years; 45% Black) reported the birth weight for each live birth and then provided documentation of birth weights (n Z 22) or reported birth weights a second time (n Z 98). RESULTS: Agreement between recalled and documented birth weights was high for first births (ICC Z 0.96) but moderate for subsequent births (ICC Z 0.59). Maternal recall was highly reliable for first births (r Z 0.95) and subsequent births (r Z 0.87), and reliability remained high when considered separately by race, education, income, and age. CONCLUSION: Women report accurate and reliable infant birth-weight data an average of 57 years after delivery, and recall is particularly precise for first births.

Stroke, 2009

Background & Purpose-Cerebral infarcts increase the risk for cognitive impairment. The relevance ... more Background & Purpose-Cerebral infarcts increase the risk for cognitive impairment. The relevance of location and number of infarcts with respect to cognitive function is less clear.

Neurobiology of Aging, 2010

Objective: To assess whether markers of micro-and macro-structural brain abnormalities are associ... more Objective: To assess whether markers of micro-and macro-structural brain abnormalities are associated with slower gait in older men and women independent of each other, and also independent of health-related conditions and of behavioral, cognitive and peripheral function.

OBJECTIVES: To examine dog walking among dog owners and the relationship between walking behavior... more OBJECTIVES: To examine dog walking among dog owners and the relationship between walking behavior of dog owners and non-dog owners and maintained gait speed over 3 years. DESIGN: Cross-sectional and longitudinal analyses of a prospective cohort study. SETTING: Memphis, Tennessee, and Pittsburgh, Pennsylvania. PARTICIPANTS: Two thousand five hundred thirty-three community-dwelling adults aged 71 to 82 at 36 months of the Health, Aging and Body Composition Study. MEASUREMENTS: Dog ownership, reported walking behavior, change in walking behavior, and usual and rapid gait speed over 3 years. RESULTS: Of 394 dog owners, only 36% walked their dogs at least three times per week. Cross-sectionally, dog walkers were more likely to achieve 150 minutes of walking per week and had faster usual and rapid walking speeds (1.20 vs 1.14 m/s and 1.62 vs 1.52 m/s, respectively; Po.01 for both) than non-dog owners who did not walk at least three times per week and similar speeds as non-dog owners who walked at least 150 minutes per week (P4.50). Three years later, subjects who had been dog walkers at baseline were approximately twice as likely as any other group to achieve recommended walking levels, independent of covariates. Dog walkers experienced similar declines in usual and rapid walking speed as non-dog owners who walked at least three times per week but maintained their initial mobility advantage. CONCLUSION: Although dog ownership appears to facilitate walking behavior, only a minority of older dog owners walk their dogs. The mobility advantage of dog ownership was seen only in dog walkers and was similar to that associated with any walking. Given suboptimal walking activity in older adults, examining the degree to which dog ownership promotes walking activity in persons who do little walking on their own appears worth pursuing.

Background. Among persons with white matter lesions (WMLs), there is a range of cognitive functio... more Background. Among persons with white matter lesions (WMLs), there is a range of cognitive function. We examine whether participation in leisure activities modifies the effect of WML load on cognitive function.

Journal of The American Geriatrics Society, 2007

OBJECTIVES: To test the hypothesis that increased long-term mortality after hospitalization for c... more OBJECTIVES: To test the hypothesis that increased long-term mortality after hospitalization for community-acquired pneumonia (CAP) is independent of comorbid conditions.DESIGN: Prospective observational cohort study in metropolitan areas.SETTING: Memphis, Tennessee, and Pittsburgh, Pennsylvania.PARTICIPANTS: Three thousand seventy-five subjects aged 70 to 79 over 5.2 years.MEASUREMENTS: Unadjusted and adjusted mortality from an initial hospitalization for CAP were compared with mortality from different causes of hospitalization, including cancer, fracture, congestive heart failure (CHF), cerebrovascular accident (CVA), and other causes. Demographics, smoking, nutritional markers, functional status, inflammatory markers, and chronic health conditions were adjusted for.RESULTS: Of the 106 subjects hospitalized for CAP, 22 (20.8%) and 38 (35.8%) died at 1 and 5 years. Subjects hospitalized with CAP had higher mortality than nonhospitalized subjects (adjusted odds ratio (OR)=7.8, 95% confidence interval (CI)=4.2–14.4). One- and 5-year mortality after CAP hospitalization were higher than mortality from other causes requiring hospitalization and remained unchanged in multivariable analysis (adjusted OR=3.5, 95% CI=1.5–8.1; adjusted OR=5.6, 95% CI=2.8–11.2, respectively). One- and 5-year mortality after hospitalization for CAP were similar to or higher than mortality after an initial hospitalization for CHF, CVA, or fracture. Rehospitalization was common in subjects hospitalized for CAP and may explain greater long-term mortality.CONCLUSION: In this high-functioning cohort of older persons, an initial hospitalization for CAP was associated with greater long-term mortality, independent of prehospitalization comorbid conditions. Hospitalization for CAP has as serious a prognosis as hospitalization for CHF, stroke, or major fracture.

Persons with type 2 diabetes are at increased risk of cognitive dysfunction. Less is known about ... more Persons with type 2 diabetes are at increased risk of cognitive dysfunction. Less is known about which cognitive abilities are affected and how undiagnosed diabetes and impaired fasting glucose relate to cognitive performance. The authors explored this question using data from 1,917 nondemented men and women (average age ¼ 76 years) in the population-based Age, Gene/Environment Susceptibility-Reykjavik Study (2002)(2003)(2004)(2005)(2006). Glycemic status groups included diagnosed diabetes (self-reported diabetes or diabetic medication use; n ¼ 163 (8.5%)), undiagnosed diabetes (fasting blood glucose !7.0 mmol/L without diagnosed diabetes; n ¼ 55 (2.9%)), and impaired fasting glucose (fasting blood glucose 5.6-6.9 mmol/L; n ¼ 744 (38.8%)). Composites of memory, processing speed (PS), and executive function were constructed from a neuropsychological battery. Linear regression was used to investigate cross-sectional differences in cognitive performance between glycemic groups, adjusted for demographic and health factors. Persons with diagnosed diabetes had slower PS than normoglycemics (b ¼ À0.12; P < 0.05); diabetes duration of !15 years was associated with significantly poorer PS and executive function. Undiagnosed diabetics had slower PS (b ¼ À0.22; P < 0.01) and poorer memory performance (b ¼ À0.22; P < 0.05). Persons with type 2 diabetes have poorer cognitive performance than normoglycemics, particularly in PS. Those with undiagnosed diabetes have the lowest cognitive performance.

American Journal of Human Genetics, 2008

White blood cell count (WBC) is an important clinical marker that varies among different ethnic g... more White blood cell count (WBC) is an important clinical marker that varies among different ethnic groups. African Americans are known to have a lower WBC than European Americans. We surveyed the entire genome for loci underlying this difference in WBC by using admixture mapping. We analyzed data from African American participants in the Health, Aging, and Body Composition Study and the Jackson Heart Study. Participants of both studies were genotyped across R 1322 single nucleotide polymorphisms that were preselected to be informative for African versus European ancestry and span the entire genome. We used these markers to estimate genetic ancestry in each chromosomal region and then tested the association between WBC and genetic ancestry at each locus. We found a locus on chromosome 1q strongly associated with WBC (p < 10 À12 ). The strongest association was with a marker known to affect the expression of the Duffy blood group antigen. Participants who had both copies of the common West African allele had a mean WBC of 4.9 (SD 1.3); participants who had both common European alleles had a mean WBC of 7.1 (SD 1.3). This variant explained~20% of population variation in WBC. We used admixture mapping, a novel method for conducting genetic-association studies, to find a region that was significantly associated with WBC on chromosome 1q. Additional studies are needed to determine the biological mechanism for this effect and its clinical implications.

Diabetes increases the risk for microvascular disease. The retina and the brain both have intrica... more Diabetes increases the risk for microvascular disease. The retina and the brain both have intricate microvascular systems that are developmentally similar. We sought to examine whether microvascular lesions in the retina and in the brain are associated and whether this association differs among people with and without diabetes. The analysis included 4,218 participants of the Icelandic population-based Age, Gene/Environment Susceptibility-Reykjavik Study who were born in 1907-1935 and who were previously followed as a part of the Reykjavik Study. Retinal focal arteriolar narrowing, arteriovenous (AV) nicking, and microaneurysms/hemorrhages were evaluated on digital retinal images of both eyes. Cerebral microbleeds (CMBs) were evaluated from magnetic resonance images. Data were analyzed with logistic and multinomial logistic regression models controlling for demographics, major cardiovascular risk factors, cerebral infarcts, and white matter lesions. Evidence of brain microbleeds was found in 485 (11.5%) people, including 192 with multiple (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;or=2) microbleeds. Subjects with signs of retinal microvascular lesions were at a significantly increased likelihood for having multiple CMBs. People with diabetes in combination with the presence of either retinal AV nicking (odds ratio [OR] 2.47 [95% CI 1.42-4.31]) or retinal microaneurysms/hemorrhages (2.28 [1.24-4.18]) were significantly more likely to have multiple CMBs. Retinal microvascular abnormalities and brain microbleeds may occur together in older adults. People with both diabetes and signs of retinal microvascular lesions (AV nicking and microaneurysms/hemorrhages) are more likely to have multiple microbleeds in the brain. Microvascular disease in diabetes extends to the brain.