Testosterone is the primary male sex hormone, crucial for maintaining fertility and maintaining male sexual characteristics. Some evidence suggests testosterone is neuroprotective. A recent study found that lower testosterone levels are linked with a higher risk for dementia.

The study involved 581 cognitively healthy older men living in China. Researchers assessed the men’s cognitive function and measured their levels of testosterone and neurofilament light chain, a structural protein that maintains neuronal health and connectivity. Neurofilament light chain is a biomarker for neuronal damage and degenerative diseases, including Alzheimer’s.

They found that men with lower testosterone levels were roughly five times more likely to experience cognitive decline than those with high levels. Those with low testosterone and high neurofilament light chain levels were approximately six times more likely to experience cognitive decline.

These findings suggest that lower testosterone and neurodegeneration synergistically contribute to cognitive decline in men. Learn more about low testosterone in this clip featuring Dr. Peter Attia.