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P2–226: Mild cognitive impairment: The diagnostic utility of initial primary care evaluation, magnetic resonance imaging and comprehensive neuropsychological assessment
Author(s) -
Harris Rebekah L.,
Cornwell Sonya L.,
Hall James R.
Publication year - 2006
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2006.05.1065
Subject(s) - dementia , medical diagnosis , neuropsychology , magnetic resonance imaging , neuropsychological assessment , memory clinic , medicine , pediatrics , disease , vascular dementia , memory impairment , psychology , psychiatry , cognition , radiology
indicated by hyperinsulinemia and peripheral insulin resistance. Objective: To examine the effect of peripheral insulin resistance on cerebral glucose metabolism at rest and during a memory task, and to evaluate whether regional changes are consistent with brain glucose metabolism changes noted for adults in the earliest stages of Alzheimer’s disease. Methods: 20 older adults, 10 of whom were insulin resistant, underwent resting and cognitive activation CMRglu PET imaging using [F-18]FDG on separate days, in counterbalanced order. Insulin resistant adults were identified using an insulin sensitivity index derived from an oral glucose tolerance test. The groups were comparable in age, education, physical health (with the exception of glucoregulatory status), and overall cognitive function. The imaging protocol consisted of a 30-minute transmission scan, an IV injection of 5 mCi [F-18]FDG, a 40-minute uptake period, and a 30-minute emission scan. In the activation condition, a 35-minute cognitive task was initiated at the time of tracer injection. For this task, subjects were instructed to remember a repeating list of 20 words that were randomly presented in series through earphones. Delayed free recall was assessed 50 minutes following task completion. PET images were analyzed using standard brain mapping techniques, and subtracted images were averaged across subjects to form statistical maps. Results: In the resting condition, CMRglu was significantly decreased for the insulin resistant adults relative to controls in right posterior parietal and left inferior temporal regions. Areas of hypermetabolism were also apparent in cortical regions surrounding the hypometabolic areas. In the activation condition, task-related activation was reduced in the right inferior frontal gyrus for insulin resistant vs. controls. Conclusion: These findings indicate that peripheral insulin resistance has clear effects on cerebral glucose metabolism, both at rest and during task performance. Moreover, these changes resemble those that have been previously reported for older adults in the preclinical stages of Alzheimer’s disease, thereby lending support to the idea that insulin dysregulation may play a role in Alzheimer pathology.