Plasma IGF-I levels and cognitive performance in older women.
BACKGROUND
Emerging biologic and epidemiologic evidence suggests benefits of insulin-like growth factor-I (IGF-I) in cognitive aging.


OBJECTIVE
To examine the relation of circulating IGF-I to cognition.


METHODS
We measured plasma IGF-I and IGF-binding protein-3 (IGFBP-3) in 590 women aged 60-68 years. An average 10 years later, we administered telephone-based tests of general cognition (Telephone Interview of Cognitive Status [TICS]), verbal memory, category fluency, and attention. We estimated multivariable-adjusted mean differences in performance across levels of IGF-I/IGFBP-3 molar ratio.


RESULTS
On the TICS, each standard deviation (S.D.) increase in molar ratio was significantly associated with better performance: multivariable-adjusted mean difference=0.2 units, 95% confidence interval (0.0,0.4), p=0.05. This effect estimate for each S.D. increase in molar ratio was cognitively equivalent to the mean difference we observed on the TICS between women 1 year apart in age. On a global score combining all tests, there was also a trend of better performance with each S.D. increase in molar ratio (p=0.07). IGF-I levels were not associated with performance in verbal memory.


CONCLUSIONS
Higher IGF-I levels may be associated with better general cognition.
Okereke
Olivia
O
Division of Aging, Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, 3rd floor, 181 Longwood Avenue, Boston, MA 02115, USA. ookereke@partners.org
Kang
Jae Hee
JH
Ma
Jing
J
Hankinson
Susan E
SE
Pollak
Michael N
MN
Grodstein
Francine
F
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001288:Attention / Q000502:physiology*; D015415:Biomarkers / Q000097:blood; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D013223:Statistics as Topic; D013647:Task Performance and Analysis
D015415:Biomarkers; D007334:Insulin-Like Growth Factor I