The Journal of Clinical Endocrinology & Metabolism. Vol. 87, No. 11 5001-5007

Longitudinal Assessment of Serum Free Testosterone Concentration Predicts Memory

Performance and Cognitive Status in Elderly Men

Scott D. Moffat, Alan B. Zonderman, E. Jeffrey Metter, Marc R. Blackman, S. Mitchell Harman

and Susan M. Resnick

Abstract

Circulating testosterone (T) levels have behavioral and neurological effects in both hu­man and nonhuman species. Both T concentrations and neuropsychological function de­crease substantially with age in men. The purpose of this prospective, longitudinal study was to investigate the relationships between age-associated decreases in endogenous se­rum T (testosterone) and free T concentrations and declines in neuropsychological per­formance. Participants were volunteers from the Baltimore Longitudinal Study of Aging, aged 50–91 yr at baseline T assessment. Four hundred seven men were followed for an average of 10 yr, with assessments of multiple cognitive domains and contemporaneous determination of serum total T, SHBG, and a free T index (FTI). We administered neuro­psychological tests of verbal and visual memory, mental status, visuomotor scanning and attention, verbal knowledge/language, visuospatial ability, and depressive symptomatol­ogy. Higher free testosterone was associated with better scores on visual and verbal memory, visuospatial functioning, and visuomotor scanning and a reduced rate of longitudinal decline in visual memory. Men classified as hypogonadal (low testoster­one) had significantly lower scores on measures of memory and visuospatial perfor­mance and a faster rate of decline in visual memory. These results suggest a possible beneficial relationship between circulating free Testosterone concentrations and spe­cific domains of cognitive performance in older men.