Lower testosterone levels in men are associated with increase dementia risk
Many studies have shown lower testosterone levels are associated with higher risk of all cause dementia and Alzheimers. The lowest quintiles of total testosterone and free testosterone have a 40-80% higher risk of dementia.
- The relationship appears to be dose dependent below of 300ng/dL
- Marked increases in cognitive impairment are seen at lower concentrations
Studies showing links testosterone and dementia:
- UK Biobank study of 159K men followed for 7 years. Those in lowest quintile of total testosterone had 43% increased risk of dementia and 80% higher risk of Alzheimers.
- Health in Men study, lowest quartiles of free and total testosterone had 40% higher dementia risk over 10 years
- Sex hormone binding globulin (SHBG) is an independent predictor of increased dementia risk. Those with highest SHBG quintile have a 32-52% increased risk of dementia and Alzheimers. What does this mean? It indicates that the bioavailable testosterone is the more relevant marker.
Subgroups of men at higher risk of dementia
- Older age. Men aged 80 or older had higher association between low testosterone and dementia
- Higher education. Men with higher education had higher dementia risk with low bioavailable testosterone.
- Sleep insufficiency. Those who have < 7 hours of sleep combined with low testosterone has a synergistic effect, increasing risk of cognitive impairment.
Why does low testosterone lead to increased dementia risk?
It is unknown. It is thought testosterone is neuroprotective. The thought is that testosterone may protect against amyloid beta accumulation (seen in Alzheimers), lower oxidative stress, and lower neuroinflammation. They do know that men with prostate cancer, which is treated purposefully by androgen deprivation, show increased dementia risk.
Does fixing testosterone levels help?
This is unclear.
- The Testosterone Trials enrolled 493 men aged ≥65 years with low testosterone and age-associated memory impairment. After one year of treatment there was no improvement in memory, language, or executive function.
- Meta analysis showed short term improvement in general cognitive function and motor response.
Some think it may just be a biomarker of higher risk, rather than a therapy.
What do we think at Biohackr Health?
Testosterone levels are a testable thing. There are ways to optimize your testosterone. There are benefits for muscle health, endurance, sex, and other health concerns. This is part of the dialogue you will have with staff at our clinic. What is your health profile? What is your level? Are you having symptoms related to testosterone? Do you have elevated dementia risk? And what is the downside? When doing testosterone therapy, we test your levels, treat, and then retest to see how you respond and if there are any other sequelae. Health issues are not black and white. You have to look at your overall body health and goals. Testosterone in men, particularly if you have a strong family history of dementia, should be part of the conversation.
- TEST
- TREAT with bioidentical hormones.
- READ our blogs on other interventions for brain health. DEMENTIA BLOGS
- DO other interventions for brain health. We at Biohackr Health in Palo Alto and SF have many different approaches for brain health- from Creatine to build muscle, our Brain IV, the test for the Alzheimer gene, continuous glucose monitors and lab tests and GLPs to control your blood sugar, labs and telehealth visits for medication to treat your cholesterol.
Dementia risk is multifactorial. Testosterone in men is one piece in that puzzle.
Medical Citations
- Lower Serum Testosterone Concentrations Are Associated With a Higher Incidence of Dementia in Men: The UK Biobank Prospective Cohort Study. Alzheimer’s & Dementia : The Journal of the Alzheimer’s Association. 2022;
- Sex Hormones and Incident Dementia in Older Men: The Health in Men Study Psychoneuroendocrinology. 2018;
- Sex Hormones and Risk of Incident Dementia in Men and Postmenopausal Women. Clinical Endocrinology. 2025;.
- The Interactive Effects of Low Testosterone and Sleep Insufficiency on Cognitive Impairment: Evidence From the NHANES 2011-2014. Psychiatry Research. 2025
- Low Testosterone and the Risk of Dementia in Elderly Men: Impact of Age and Education. Alzheimer’s & Dementia : The Journal of the Alzheimer’s Association. 2014
- Testosterone Treatment and Cognitive Function in Older Men With Low Testosterone and Age-Associated Memory Impairment. JAMA. 2017
- Efficacy and Safety of Testosterone Treatment in Men: An Evidence Report for a Clinical Practice Guideline by the American College of Physicians. Annals of Internal Medicine. 2020
- Testosterone and Cognitive Impairment or Dementia in Middle-Aged or Aging Males: Causation and Intervention, a Systematic Review and Meta-Analysis. Journal of Geriatric Psychiatry and Neurology. 2021;
- Testosterone, Cognitive Decline and Dementia in Ageing Men. Reviews in Endocrine & Metabolic Disorders. 2022Type of Androgen Deprivation Therapy and Risk of Dementia Among Patients With Prostate Cancer in Taiwan. JAMA Network Open. 2020