Sex hormone binding globulin and verbal memory in older men.

OBJECTIVE: Cognitive function in older adults may be affected by multiple factors, such as sex hormone levels, metabolic disturbances, and neuropsychiatric illness. However, relatively few studies have tested the associations between these factors and cognitive function in a single sample. A cross-sectional analysis was conducted to examine the association between sex hormones, metabolic parameters, and psychiatric diagnoses with verbal memory in nondemented older men.

METHODS: Participants were 112 men (mean age: 61.3 years) from the Baltimore Epidemiologic Catchment Area Follow-Up Study who completed measures of blood sex hormone levels, metabolic parameters (e.g., lipid profiles), and verbal memory.

RESULTS: Higher levels of serum sex hormone binding globulin (SHBG) were associated with lower delayed verbal memory scores (standardized coefficients [beta]=-0.19, t=-2.07, df=1, 105, p=0.04), and higher body mass index (BMI) was associated with better immediate (beta=0.21, t=2.41, df=1,105, p=0.02) and delayed (beta=0.22, t=2.46, df=1,105, p=0.02) verbal memory performance after adjustment for age, education, and psychiatric disorders. There was an inverse correlation between SHBG levels and BMI (Pearson's r=-0.37, N=112, p<0.001). Estimated free testosterone levels revealed curvilinear associations with verbal memory performance.

CONCLUSION: Our data suggest that higher SHBG levels are associated with worse verbal memory, whereas a higher BMI is associated with better verbal memory in older men. Higher SHBG levels due to lower adiposity may be a risk factor for cognitive dysfunction. The mechanisms linking SHBG to cognitive function have yet to be elucidated.