Project Topics
Alzheimer’s disease, hormones, and diet
Testosterone and fish oil (DHA) are promising supplements for reducing the risk of developing memory problems and Alzheimer’s disease. A clinical trial is underway to evaluate their influence on men with memory complaints by measuring the development of amyloid plaque in the brain – a hallmark of Alzheimer’s disease.
Understanding the effects of testosterone and fish oil for Alzheimer’s disease prevention
Testosterone levels in both men and women decline with age, and low testosterone levels have been related to memory problems. Studies have shown that low testosterone levels have preceded cognitive impairment and the neuropathology of Alzheimer’s, indicating it may be more of a cause than a consequence of the disease. The relationship between testosterone replacement therapy in men and women has been harder to quantify due in part to the small number of long-term, controlled studies available.
Another factor critical to brain function is omega-3 fatty acids, including DHA and EPA which usually come from fish oil. In the brains of older people, there is a depletion of long chain omega-3 fatty acids, and those with Alzheimer’s disease have lower DHA levels. DHA supplements can reduce markers of inflammation, which may influence Alzheimer’s disease. In dietary intervention studies, supplementation with DHA and/or EPA seems to be more effective in improving cognition in early stages of cognitive impairment.
Research on the impact of testosterone and dietary supplements is complex and studies frequently report conflicting results. This may be due to the many individual factors that can affect outcomes, brief follow up, different methods, and lack of comparable imaging data. Long-term randomized clinical trials are needed before conclusions can be made.
Clinical trial on testosterone and fish oil
To help understand the influence of testosterone and fish oil for Alzheimer’s disease and memory, the Parsemus Foundation provided early support for a randomized controlled prospective trial on the impact of testosterone or DHA versus placebo on the onset of amyloid plaque associated with Alzheimer’s disease in men with memory complaints. The study is being conducted at the McCusker Alzheimer’s Research Foundation in Western Australia (now called Alzheimer’s Research Australia). Based on the results of a smaller non-placebo trial, the researchers led by Dr. Ralph Martins are optimistic that one or both treatments may slow the development of amyloid plaque and cognitive decline.
The trial has been screening men by completing a positron emission tomography (PET) amyloid scan prior to selection for the trial. The enrollment goal is expected to be met in mid-2023 with completion of the trial data collection in 2024. In addition to the treatment arms, blood tests and retinal images from all participants will help to develop early diagnostic tests for Alzheimer’s disease.
Take Action on Testosterone and Fish Oil for Alzheimer’s Disease Prevention
Learn more about dementia and Alzheimer’s disease – and what you can do to lower your risk. There are many lifestyle changes that can reduce the chance of developing Alzheimer’s disease, such as diet, exercise, and appropriate supplements. See Additional Resources below.
Additional Resources
For general information, research trials, and prevention information regarding Alzheimer’s disease, see: Alzheimer’s Association, Alzheimer’s Research and Prevention Foundation, Australian Alzheimer’s Foundation, list of Alzheimer’s Research Centers and Organizations.
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- Thota RN, Rosato JI, Burrows TL et al. (2020). Docosahexaenoic acid-rich fish oil supplementation reduces kinase associated with insulin resistance in overweight and obese midlife adults. Nutrients 12(6), 1612. (Free full text).
- Vlachos GS, Scarmeas N. (2019). Dietary interventions in mild cognitive impairment and dementia. Dialogues Clin Neurosci 21(1):69-82. (Free full text).
- Tan S, Sohrabi HR, Weinborn M et al. (2019). Effects of testosterone supplementation on separate cognitive domains in cognitively healthy older men: A meta-analysis of current randomized clinical trials. Am J Geriatr Psychiatry 27(11):1232-1246. (Abstract)
- Martins RN, Villemagne V, Sohrabi HR, et al. (2018). Alzheimer’s disease: A journey from amyloid peptides and oxidative stress, to biomarker technologies and disease prevention strategies-Gains from AIBL and DIAN cohort studies. J Alzheimers Dis. 62(3):965-992. (Free full text).
- Asih PR, Tegg ML, Sohrabi H, Carruthers M, Gandy SE, Saad F, Verdile G, Ittner LM, Martins RN. (2017). Multiple mechanisms linking type 2 diabetes and Alzheimer’s disease: Testosterone as a modifier. J Alzheimers Dis. 59(2): 445–466. (Free full text).
- Wahjoepramono EJ, Asih PR, Aniwiyanti V et al. (2016). The effects of testosterone supplementation on cognitive functioning in older men. CNS Neurol Disord Drug Targets. 15(3): 337–343. (Free full text)
- Thomas J, Thomas CJ, Radcliffe J, Itsiopoulos C. (2015). Omega-3 fatty acids in early prevention of inflammatory neurodegenerative disease: A focus on Alzheimer’s disease. Biomed Res Int. 2015:172801. (Free full text).
- Last updated on February 21, 2024
Human Health News
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Shingles vaccine may lower dementia risk
The recombinant zoster vaccine known as SHINGRIX may also lower the risk of developing dementia, according to a new study. The vaccine prevents shingles, a painful viral infection, and is typically recommended for those 50 and older. Researchers in the U.K. published a study in Nature Medicine on July 25 that showed that among people diagnosed with dementia, those who received the recombinant zoster vaccine had more diagnosis-free time compared with those who received a different vaccine.
Cognitive dysfunction syndrome in cats similar to Alzheimer’s disease
House cats live an average of 14 years, and it’s not uncommon for a cat to live more than 20 years. Older cats often develop cognitive decline resulting in dementia. It’s called “cognitive dysfunction syndrome” or CDS. This condition is similar in many ways to Alzheimer’s disease, including amyloid beta and tau protein accumulation. Some believe that environmental stressors from life as a house cat contribute to cognitive decline.
Ultra-processed foods affect brain health
Recent research has revealed that eating ultra-processed foods affects brain health. Studies suggest that diets high in these foods could increase the risk of cognitive impairment and stroke. Ultra-processed foods include industrially prepared items like packaged snacks, ready-made meals, and sugary drinks. These foods are often convenient, but they carry hidden health dangers.
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