This Article  • Full text  • PDF  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Citing articles on HighWire  • Citing articles on ISI (13)  • Contact me when this article is cited  Related Content  • Similar articles in this journal  Topic Collections  • Neurology  • Women's Health  • Women's Health, Other  • Alert me on articles by topic

Olivia Okereke, MD, SM; Susan E. Hankinson, ScD; Frank B. Hu, MD, PhD; Francine Grodstein, ScD

Arch Intern Med. 2005;165:1651-1656.

Background  Growing evidence suggests that type 2 diabetes mellitus and hyperinsulinemia may be related to diminished cognition. To help differentiate between the effects of diabetes and insulin, we examined the relation of insulin to cognitive function among nondiabetic participants of the Nurses’ Health Study.

Methods  We measured the C peptide level, representing insulin secretion, in blood samples provided by 718 women from June 14, 1989, to October 4, 1990, when they were aged 61 to 69 years. We administered telephone interviews an average of 10 years after blood collection, testing general cognition, verbal memory, category fluency, and attention; second cognitive assessments were conducted 2 years later. The primary outcomes were global cognitive function across all tests and verbal memory. We used regression models to estimate multivariable-adjusted mean differences in cognitive function and cognitive decline, and odds of cognitive impairment, across C peptide levels.

Results  Cognitive function was worse among women in the fourth C peptide quartile compared with those in the first quartile (eg, on the global score combining all cognitive tests, the multivariable-adjusted mean difference was –1.7 standard units [95% confidence interval, –2.9 to –0.6 standard units]; P = .002); the odds of cognitive impairment (defined as the worst 10% of the distribution) were 3-fold higher among women in the fourth vs first quartile (95% confidence interval, 1.3-7.8). On verbal memory, women in the fourth quartile scored significantly worse than those in the first quartile; the odds of impairment were 2.8-fold higher (95% confidence interval, 1.1-7.0). Consistent findings were observed for cognitive decline.

Conclusion  Higher insulin secretion may be related to worse cognition, even among those without diabetes.

Author Affiliations: Division of Aging (Drs Okereke and Grodstein) and Channing Laboratory (Drs Okereke, Hankinson, and Grodstein), Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Mass; and Departments of Epidemiology (Drs Hankinson and Grodstein) and Nutrition (Dr Hu), Harvard School of Public Health, Boston.

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

Amelioration of Cognitive Impairment in the Type-2 Diabetic Mouse by the Angiotensin II Type-1 Receptor Blocker Candesartan
Tsukuda et al.
Hypertension 2007;50:1099-1105.
ABSTRACT | FULL TEXT  

Peripheral insulin and brain structure in early Alzheimer disease
Burns et al.
Neurology 2007;69:1094-1104.
ABSTRACT | FULL TEXT  

From Depression to Where Are My Keys: Unlocking the Behavioral Disorders of Old Age
Smith
AJGP 2006;14:989-992.
FULL TEXT  

Plasma C-Peptide and Cognitive Performance in Older Men Without Diabetes
Okereke et al.
AJGP 2006;14:1041-1050.
ABSTRACT | FULL TEXT  

Hyperinsulinemia and Cognitive Decline in a Middle-Aged Cohort
Young et al.
Diabetes Care 2006;29:2688-2693.
ABSTRACT | FULL TEXT