1. |
- de Frias, Cindy M., et al.
(författare)
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Catechol O-Methyltransferase Val¹-sup-5-sup-8 Met Polymorphism is Associated with Cognitive Performance in Nondemented Adults.
- 2005
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Ingår i: Journal of Cognitive Neuroscience. - : MIT Press - Journals. - 0898-929X .- 1530-8898. ; 17:7, s. 1018-1025
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Tidskriftsartikel (refereegranskat)abstract
- The catechol O-methyltransferase (COMT) gene is essential in the metabolic degradation of dopamine in the prefrontal cortex. In the present study, we examined the effect of a Val¹-sup-5-sup-8Met polymorphism in the COMT gene on individual differences and changes in cognition (executive functions and visuospatial ability) in adulthood and old age. The participants were 292 nondemented men (initially aged 35-85 years) from a random sample of the population (i.e., the Betula study) tested at two occasions with a 5-year interval. Confirmatory factor analyses were used to test the underlying structure of three indicators of executive functions (verbal fluency, working memory, and Tower of Hanoi). Associations between COMT, age, executive functioning, and visuospatial (block design) tasks were examined using repeated-measures analyses of variance. Carriers of the Val allele (with higher enzyme activity) compared with carriers of the Met/Met genotype (with low enzyme activity) performed worse on executive functioning and visuospatial tasks. Individuals with the /Val genotype declined in executive functioning over the 5-year period, whereas carriers of the Met allele remained stable in performance. An Age × COMT interaction for visuospatial ability located the effect for middle-aged men only. This COMT polymorphism is a plausible candidate gene for executive functioning and fluid intelligence in nondemented middle-aged and older adults.
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2. |
- de Frias, Cindy M, et al.
(författare)
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Catechol O-methyltransferase Val158Met polymorphism is associated with cognitive performance in nondemented adults.
- 2005
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Ingår i: Journal of cognitive neuroscience. - Cambridge : MIT Press - Journals. - 0898-929X .- 1530-8898. ; 17:7, s. 1018-25
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Tidskriftsartikel (refereegranskat)abstract
- The catechol O-methyltransferase (COMT) gene is essential in the metabolic degradation of dopamine in the prefrontal cortex. In the present study, we examined the effect of a Val158Met polymorphism in the COMT gene on individual differences and changes in cognition (executive functions and visuospatial ability) in adulthood and old age. The participants were 292 nondemented men (initially aged 35-85 years) from a random sample of the population (i.e., the Betula study) tested at two occasions with a 5-year interval. Confirmatory factor analyses were used to test the underlying structure of three indicators of executive functions (verbal fluency, working memory, and Tower of Hanoi). Associations between COMT, age, executive functioning, and visuospatial (block design) tasks were examined using repeated-measures analyses of variance. Carriers of the Val allele (with higher enzyme activity) compared with carriers of the Met/Met genotype (with low enzyme activity) performed worse on executive functioning and visuospatial tasks. Individuals with the Val/Val genotype declined in executive functioning over the 5-year period, whereas carriers of the Met allele remained stable in performance. An Age x COMT interaction for visuospatial ability located the effect for middle-aged men only. This COMT polymorphism is a plausible candidate gene for executive functioning and fluid intelligence in nondemented middle-aged and older adults.
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3. |
- de Frias, Cindy M., et al.
(författare)
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Characterizing executive functioning in older special populations : From cognitively elite to cognitively impaired
- 2009
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Ingår i: Neuropsychology. - : American Psychological Association. - 0894-4105 .- 1931-1559. ; 23:6, s. 778-791
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Tidskriftsartikel (refereegranskat)abstract
- The authors examined the structure and invariance of executive functions (EF) across (a) a continuum of cognitive status in 3 groups of older adults (cognitively elite [CE], cognitively normal [CN], and cognitively impaired [CI]) and (b) a 3-year longitudinal interval. Using latent variable analyses (LISREL 8.80), the authors tested 3-factor models (“Inhibition”: Hayling [Burgess & Shallice, 1997], Stroop [Regard, 1981]; “Shifting”: Brixton [Burgess & Shallice, 1997], Color Trails [D’Elia et al., 1996]; and “Updating”: Reading and Computational Span [Salthouse & Babcock, 1991]) and 1-factor models within each group. Participants (initial N = 570; 53–90 years) were from the Victoria Longitudinal Study (Sample 3, Waves 1 and 2). Cross-sectionally, the authors observed a 3-factor EF structure especially for the CE group and 1-factor solutions for all 3 groups. Longitudinally, temporal invariance was supported for the 3-factor model (CE and CN groups) and the 1-factor model (CI and CN groups). Subgroups with higher cognitive status and greater 3-year stability performed better on EF factors than corresponding groups with lower cognitive status and less stability. Studies of EF structure, performance, dedifferentiation, and dysfunction will benefit from considering initial cognitive status and longitudinal stability.
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4. |
- de Frias, Cindy M., et al.
(författare)
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Cholesterol and triglycerides moderate the effect of apolipoprotein E on memory functioning in older adults.
- 2007
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Ingår i: Journal of Gerontology: Psychological Sciences. - Washington : The gerontological society of America. - 1079-5014 .- 1758-5368. ; 62B:2, s. P112-P118
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Tidskriftsartikel (refereegranskat)abstract
- We used data from the Betula Study to examine associations between total cholesterol, triglycerides, and apolipoprotein E on 10-year changes in cognitive performance. Tests assessing episodic memory (recall and recognition), semantic memory (knowledge and fluency), and visuospatial ability (block design) were administered to 524 nondemented adults (initial age of 55-80 years); multilevel modeling was applied to the data. Higher triglyceride levels were associated with a decline in verbal knowledge. Lipid levels moderated the influence of apolipoprotein E on episodic memory, such that among epsilon 4 allele carriers, decline in recognition was noted for individuals with higher cholesterol levels. Cholesterol and triglyceride levels are pharmacologically modifiable risk factors that account for variation In normal cognitive aging.
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5. |
- de Frias, Cindy M, et al.
(författare)
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COMT gene polymorphism is associated with declarative memory in adulthood and old age.
- 2004
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Ingår i: Behavior genetics. - New York : Kluwer Academic Publishers. - 0001-8244 .- 1573-3297. ; 34:5, s. 533-9
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Tidskriftsartikel (refereegranskat)abstract
- Variation in memory performance is to a large extent explained by genes. In the prefrontal cortex, the catechol O-methyltransferase (COMT) gene is essential in the metabolic degradation of dopamine, a neurotransmitter implicated in cognitive functions. The present study examined the effect of a polymorphism in the COMT gene on individual differences and changes in memory in adulthood and old age. Tests assessing episodic and semantic memory were administered to 286 men (initially aged 35-85 years) from a random sample of the population (i.e., the Betula prospective cohort study) at two occasions followed over a 5-year period. Carriers of the Met/Met genotype (with low enzyme activity) performed better on episodic and semantic memory, as compared to carriers of the Val allele (with higher enzyme activity). Division of episodic memory into its recall and recognition components showed that the difference was specific to episodic recall, not recognition tasks; an effect that was observed across three age groups (middle-age, young-old, and old-old adults) and over a 5-year period. The COMT gene is a plausible candidate gene for memory functioning in adulthood and old age.
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6. |
- de Frias, Cindy M., et al.
(författare)
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Influence of COMT Gene Polymorphism on fMRI-assessed Sustained and Transient Activity during a Working Memory Task
- 2010
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Ingår i: Journal of cognitive neuroscience. - Cambridge, Mass. : MIT Press. - 0898-929X .- 1530-8898. ; 22:7, s. 1614-1622
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Tidskriftsartikel (refereegranskat)abstract
- The catechol O-methyltransferase (COMT) gene-encoding an enzyme that is essential for the degradation of dopamine (DA) in prefrontal cortex (PFC)-contains a single nucleotide polymorphism (val/met) important for cognition. According to the tonic-phasic hypothesis, individuals carrying the low-enzyme- activity allele (met) are characterized by enhanced tonic DA activity in PFC, promoting sustained cognitive representations in working memory. Val carriers have reduced tonic but enhanced phasic dopaminergic activity in subcortical regions, enhancing cognitive flexibility. We tested the tonic-phasic DA hypothesis by dissociating sustained and transient brain activity during performance on a 2-back working memory test using mixed blocked/event-related functional magnetic resonance imaging. Participants were men recruited from a random sample of the population (the Betula study) and consisted of 11 met/met and 11 val/val carriers aged 50 to 65 years, matched on age, education, and cognitive performance. There were no differences in 2-back performance between genotype groups. Met carriers displayed a greater transient medial temporal lobe response in the updating phase of working memory, whereas val carriers showed a greater sustained PFC activation in the maintenance phase. These results support the tonic-phasic theory of DA function in elucidating the specific phenotypic influence of the COMT val(158)met polymorphism on different components of working memory.
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7. |
- de Frias, Cindy, et al.
(författare)
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Revisiting the dedifferebtion hypothesis with longitudinal multi-cohort data
- 2007
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Ingår i: Intelligence. ; 35, s. 381-392
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Tidskriftsartikel (refereegranskat)abstract
- The present longitudinal multi-cohort study examines whether interindividual variability in cognitive performance and change increases in old age, and whether associations among developments of different cognitive functions increase with adult age. Multivariate multiple-group latent growth modeling was applied to data from narrow cohorts separated by five years of age. Tests assessing episodic recall, semantic knowledge, semantic fluency, and visuospatial ability were administered to 1000 non-demented adults (initially aged 35–80 years), participating in the Betula Project at three occasions over a 10-year period. Greater interindividual differences in change were noted in older age groups. Age-related increases in correlations among performance scores were noted for different cognitive measures beginning in old age, but not earlier. Our study supports a dynamic view of dedifferentiation of cognitive aging.
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8. |
- de Frias, Cindy, et al.
(författare)
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Sex differences in cognition are stable over a 10-year period in adulthood and old age.
- 2006
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Ingår i: Aging, Neuropsychology and Cognition. - : Informa UK Limited. - 1382-5585 .- 1744-4128. ; 13:3-4, s. 574-587
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Tidskriftsartikel (refereegranskat)abstract
- Sex differences in declarative memory and visuospacial ability are robust in cross-sectional studies. The present longitudinal study examined whether sex differences in cognition were present over a 10-year period, and whether age modified the magnitude of sex differences. Tests assessing episodic and semantic memory, and visuospatial ability were administered to 625 nondemented adults (initially aged 35-80 years), participating in the population based Betula study at two follow-up occasions. There was stability of sex differences across five age groups and over a 10-year period. Women performed at a higher level than men on episodic recall, face and verbal recognition, and semantic fluency, whereas men performed better than women on a task assessing visuospatial ability. Sex differences in cognitive functions are stable over a 10-year period and from 35 to 90 years of age. Decreasing levels of estrogen in women and sex differences in age-related cortical atrophy do not seem to influence cognitive sex differences.
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9. |
- Dixon, Roger A., et al.
(författare)
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Long-term Stability and Variability in Memory Compensation among Older Adults : Evidence from the Victoria Longitudinal Study
- 2009
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Ingår i: Acta Psychologica Sinica. - : Science Press. - 0439-755X. ; 41:11, s. 1091-1101
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Tidskriftsartikel (refereegranskat)abstract
- Two memory status groups were derived from a parent sample of older adults participating in the Victoria Longitudinal Study (VLS) in Canada. A not impaired control (NIC) group and a mild memory deficit (MMD) group were compared at baseline and longitudinally (over five waves or 12 years) regarding their use of memory compensation techniques in everyday life. We used multi-level modeling (covarying age and education) to examine baseline level differences and long-term change patterns. Baseline results showed that the MMD participants reported greater recent increases in memory compensation strategy use in everyday life. Longitudinal results showed notable 12-year stability in memory compensation use, but group-related differences in the compensatory mechanism of effort. The covariate of education (potentially a marker of cognitive reserve) was associated with differential change in three memory compensation strategies over time.
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