Natural age related declines in testosterone (T) are associated with decreases in cognitive abilities independent of health status. Low T levels over time are associated with increased risk for developing Alzheimer's disease (AD). These findings suggest that men with low T levels are most at risk for age-related cognitive decline and AD and therefore most likely to benefit from T supplementation to prevent the development of AD or age-associated cognitive decline. The current study will assess cognition, mood, and cerebral spinal fluid (CSF) biomarker response to T supplementation in older men with mild cognitive impairment (MCI) and low T levels.~Participants will be randomized to either receive T treatment or a placebo for six months. Participants will come in for about five visits within the span of six months where they will complete cognitive & memory tests, fill out mood questionnaires, and have their blood drawn to monitor the medication level. A sample of blood will also be taken at one visit to test for apolipoprotein E (APOE), which is a genetic risk factor associated with AD. Participants will have the option to get a spinal tap in order to measure biological markers associated with Alzheimer's disease including beta-amyloid 1-40, 42, total-tau, and phosphorylated-tau-181-231. This will require an additional two visits.
The purpose of this study is to examine the effects of testosterone (T) replacement on changes in thinking and memory, as well as mood in older men with mild cognitive impairment (MCI) and low T levels. The study will also examine whether taking testosterone has effects on biological markers related to Alzheimer's disease.