November 2025
Ways to Prevent and Delay Cognitive Decline As We Age
A number of tools, tests and programs aim to help people identify their chances of cognitive decline and recommend ways to delay or prevent it. These days everyone has questions about maintaining brain health and cognitive function as they age. Here we’ve listed a number of things all of us are able to do.
Having a family history of Alzheimer’s Disease (AD) in first-degree relatives does substantially increase risk of AD. However, it is estimated that while about 55% of late-onset AD (after age 65) risk is genetic, 45% of the risk is from lifestyle/environment and is potentially modifiable. It’s also important to note that AD is just one type of dementia and there are other types that can be dramatically affected by lifestyle changes which could either prevent or delay decline. Likewise, having risk factors or family history never means that there is no hope. Many people who have strong family histories never go one to develop the disease, even those with brain scans positive for illness. Lifestyle changes have been shown to delay progression in individuals suffering with cognitive impairment. While there is no guarantee of a long, healthy life, one can certainly tip the odds in their favor.
Regular physical exercise is the single most effective intervention that can improve brain health. Higher levels of physical activity have been associated with lower risk of developing dementia, including Alzheimer’s disease. The magnitude of risk reduction can be up to 20-40% and appears to be robust even after adjusting for potential confounders such as age, gender, genetic risk, and education. In addition, people with higher levels of physical activity have bigger brains on MRI scanning. On the contrary, lower levels of physical activity are associated with higher risk for developing dementia in people aged 60 and older. No matter how busy you are, try to incorporate some level of physical activity every day. It may only be a brisk walk at lunchtime or right after work, or some light resistance exercise in the evening. When you have more time, add in longer walks, more resistance training using bands or light weights, or yoga or a similar meditative/stretching/balance routine.
Nutrition scientists are still trying to figure out the healthiest diet to protect the brain. A growing body of research is giving us clues about the links between certain foods or dietary patterns and healthy brain aging. Epidemiological research (greater than 30 years) shows that diets high in vegetables (leafy green), fruits (berries), whole grains, nuts, healthy oils/fats, and fish were associated with better cognitive and mental health in older age. You might recognize this as the Mediterranean Diet. The MIND diet stands for Mediterranean-DASH Diet Intervention for Neurogenerative Delay. This diet combines two healthy strategies: The Mediterranean Diet along with the DASH diet, which helps lower blood pressure by reducing salt and processed foods while adding more nutrient-rich foods. These eating plans have shown over the decades to help prevent cognitive decline and protect brain function.
Other daily habits that can help keep the brain active are things like joining clubs or doing volunteer work. A walking club would have double the benefits of socialization and physical activity. Social isolation has been shown to have a detrimental effect on brain health. As well, sleep is a physiological process that is essential to consolidate memories and clear metabolites and toxins from the brain. The current thinking is that during REM sleep, the brain’s glymphatic system removes neurotoxins, including amyloid-beta, the protein that accumulates in the brains of people with Alzheimer’s disease. Do your best to have a quiet, gadget-free bedroom that is cool and dark, and try to avoid sedatives like diphenhydramine (an ingredient in Benadryl and the popular “PM” medications like Tylenol PM and Advil PM) and other sleeping medications. These ingredients, especially diphenhydramine, have been shown to disrupt REM and deep sleep, and in research have been associated with significant increased risk for developing dementia, especially in long-term users of these medications.
Some of the routine tests that you can complete to check on brain health are things like maintaining a healthy blood pressure, as this component of health has the strongest evidence for lowering risk of cognitive impairment. Another screening is a baseline test for cognitive functioning around the age of 65 that can help detect early signs of cognitive, memory or thinking impairment. Ask your physician to monitor your blood levels for Vitamin B12 and folate, as deficiencies in these vitamins have been implicated in cognitive changes and higher risk for dementia. This is especially important in vegans and vegetarians, as B12 is not generally found in plant foods and is critical for brain and nerve function. There is also evidence linking low Vitamin D levels with dementia risk, although this is inconclusive due to reverse causation. A person who eats a good, balanced, and varied diet doesn’t need a multivitamin, but most people require some level of specific supplementation for these 3 nutrients (B12, folate, D). Those who have a suboptimal diet or issues with malabsorption may benefit from more intense supplementation. Your physician or registered dietitian will be able to advise you about the best supplement plan for you.
Zaldy Tan, MD, Amy Dockster Marcus and Alex James