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Dopamine D2 Receptor Gene Taq1 A Polymorphism Is Associated with Cognitive Performance in Elderly Males without Dementia

Hsiang-Hsuan Huang, Chen-Jee Hong, Heng-Liang Yeh, Ying-Jay Liou, Albert C. Yang, Mu-En Liu, Shih-Jen Tsai

Objective: Dopaminergic function has been implicated in cognitive function.
The objective of this study was to explore the association of the functional dopamine
D2 receptor (DRD2) Taq1 A polymorphism (rs1800497) and cognitive performance
in the male elderly without dementia. Method: We genotyped homogeneous
population of ethnic Han Chinese aged male Taiwanese (N = 192) for the
DRD2 Taq1 A polymorphism, and assessed them with a comprehensive neuropsychological
measurement (Cognitive Abilities Screening Instrument Chinese version,
CASI C-2.0) and the Wechsler Digit Span Task tests. The genotypic group
differences of the DRD2 Taq1 A polymorphism in CASI cognitive profi les and the
Wechsler Digit Span Task test were examined. Results: Subjects with DRD2 Taq1
A1/A2 and A2/A2 genotypes had signifi cantly higher total CASI scores than those
with A1/A1 genotype (p = 0.013). Of the nine domains of CASI, “orientation” and
“short term memory” were found to be signifi cantly associated with the DRD2
genotypes (p = 0.015 and 0.035, uncorrected). No genetic effect for this polymorphism
was found in the Digit Span Task tests. Conclusion: In this study, we found
that a nominal association existed between DRD2 Taq1 A polymorphism and CASI
scores, particularly in the “orientation” and “short term memory” domains. The
results suggest that the DRD2 Taq1 A polymorphism plays a role in specifi c cognitive
functions in the normal male elderly Taiwanese.
Key Word Aged, cognitive function, dopamine D2 receptor, polymorphism
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