Objective: The aim of the present study was to find the relationship between striatal dopamine transporter (DAT) and cognitive function in healthy subjects and these relationships were explored in regard to aging.

Background: Cognitive function, such as speed of information processing, attention, and executive control, as well as striatal dopamine function decline by normal aging. The association among the striatal dopaminergic system, age and the cognitive function in healthy subjects remains to be unclear.

Methods: The 30 healthy volunteers were enrolled in this research. The age ranged from 41 to 82 (64.5 ± 11.5, mean ± SD). All subjects were scanned with both T1-weighted MRI and 123I-FP-CIT SPECT images. The Wechsler Adult Intelligence Scale－Third Edition (WAIS Ⅲ) was performed to evaluate the cognitive function. Each WAIS Ⅲ subscores were not adjusted by age. Six spherical regions of interest (ROI), 10mm in diameter, were manually drawn on the caudate nucleus, anterior putamen, and posterior putamen by utilizing MRI. ROIs were applied to spatially fused SPECT image. Striatal occipital ratio (SOR) was calculated by (specific binding/occipital lobe binding) -1. The relationship between SOR values (dependent variables) and WAIS Ⅲ subscores (independent variables) was analyzed by multiple regression analyses. WAIS Ⅲ subscores significant in multiple regression analyses were further analyzed by path analyses including age as mediator.

Results: Multiple regression analyses revealed that coding digit symbol subscore correlated with SOR value in all striatal regions except for the left caudate nucleus (R > 0.4, P < 0.04). Picture completion subscore and SOR value in the right caudate nucleus (R = 0.559, P = 0.002), similarities subscore and SOR value in the left caudate nucleus also showed the positive correlation (R = 0.402, P = 0.016). Path analyses revealed the association between (1) right caudate nucleus SOR value and picture completion subscore (p < 0.02), (2) left caudate nucleus SOR value and similarities subscore (p < 0.04) (3) age correlated with both right and left caudate nucleus SOR values (p < 0.02). Coding digit symbol subscore did not show any significant relationship by this model.

Conclusions: In healthy subjects, right caudate DAT binding is associated with picture completion subscore and left caudate DAT binding is related to similarities subscore. Age did not influence these two cognitive subscores.

References: [1] Lyn Harper Mozley, Ruben C, et al. Striatal Dopamine Transporters and Cognitive Functioning in Healthy Men and Women. (Am J Psychiatry 2001; 158:1492–1499). [2] R Cools, M D’Esposito. Inverted-U shaped dopamine actions on human working memory and cognitive control Biol Psychiatry. 2011 Jun 15; 69(12): e113–e125.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognition-related-to-striatal-dopaminergic-function-in-healthy-subjects-in-consideration-to-aging/