Monday, November 10, 2008

Insulin Resistance and Executive Dysfunction in Older Persons

Wiley InterScience :: JOURNALS :: Journal of the American Geriatrics Society


Objectives: To evaluate the association between insulin resistance (IR) and executive dysfunction in a large, population-based study of older persons without diabetes mellitus (DM) or dementia.


Measurements: Anthropometric measurements; plasma fasting levels of glucose, insulin, cholesterol (total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol), and insulin-like growth factor-1 (IGF-1); homeostasis model assessment (HOMA) to estimate degree of IR; Trail Making Test (TMT) A; TMT-B; TMT-B minus TMT-A (DIFF B–A); and Mini-Mental State Examination (MMSE).

Results: IR (HOMA) was associated with longer TMT-B (correlation coefficient (r)=0.11; P=.006) and DIFF B–A times (r=0.10; P=.022). Subjects in the upper tertile of IR were older and had longer TMT-B and DIFF B–A than participants in the lowest tertile. After adjusting for age, sex, and years of formal education, IR was significantly correlated with TMT-A, TMT-B, and DIFF B–A. After adjusting for age, sex, education, body mass index, waist:hip girth ratio, HDL-C, triglycerides, IGF-1, hypertension, drug intake, and physical activity, the results did not significantly change. After introducing MMSE score into the model, IR continued to be an independent determinant of TMT-A (β=11.005; P=.021), TMT-B (β=28.379; P<.001), and DIFF B–A (β=17.374; P=.011).

Conclusion: IR is independently associated with frontal cortex function evidenced by poor TMT times in older persons without DM or dementia.

Diabetes and executive dysfunction go hand in hand. Executive dysfunction is a hallmark of ADD.

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