Cherrier, M. M.Mohan, S.Matsumoto, Alvin M.Peskind, E.Latendresse, S.Bremner, William J.Raskind, M.Craft, S.Plymate, Stephen R.Haley, A. P.Asthana, S.2008-10-172008-10-172004-01Psychoneuroendocrinology. 2004 Jan;29(1):65-82http://hdl.handle.net/1773/4330BACKGROUND: Our laboratory has previously reported that testosterone (T) administration to older men significantly improves cognitive function. This study examined potential changes in insulin-like growth factor (IGF) IGF-I, IGF-II and IGF-related binding proteins in response to T administration in older men and their relationship to cognitive functioning. METHODS: Twenty-five healthy community dwelling volunteers, ranging in age from 50-80 years were randomized to receive weekly intra-muscular (i.m.) injections of either 100 mg T enanthate or placebo (saline) for 6 weeks. Serum hormone levels and cognitive functioning was assessed at baseline and twice during treatment. RESULTS: Significant positive associations between IGF-I and IGF-II and spatial memory, spatial reasoning, and verbal fluency were observed after 6 weeks of T administration. Increased serum T levels from treatment were positively associated with improvement in spatial reasoning performance, whereas estradiol was associated with a decline in divided attention performance. Serum IGF-I, IGF-II and IGFBPs did not change in response to T treatment. CONCLUSIONS: Our results suggest that T, estradiol and IGF-I may have independent and selective effects on cognitive functioning. Positive associations between T levels and cognition are consistent with an effect of androgen treatment, whereas positive associations between IGF-I levels and cognition are reflective of a relationship between endogenous IGF-I levels and cognition.en-UStestosteronegonadotropinsmale contraception5-alpha reductase inhibitorsklinefelter's syndromespermatogenesisandrologycolchicinereifenstein's syndromeResearch Support, Non-U.S. Gov'tAgedVerbal Learning, physiologyMaleSpatial Behavior, physiologyInsulin-Like Growth Factor I, metabolismTestosterone, administration & dosage, physiologyMiddle AgedAged, 80 and overAnalysis of VarianceResearch Support, U.S. Gov't, P.H.S.HumansResearch Support, U.S. Gov't, Non-P.H.S.Insulin-Like Growth Factor II, metabolismCognition, physiologyInsulin-Like Growth Factor Binding Proteins, bloodAttention, physiologyEstradiol, bloodArticle