Evidence-based ways to prevent cognitive decline

By Naveed Saleh, MD, MS
Published July 31, 2020

Key Takeaways

Cognitive decline impairs quality of life, threatens independence, and places more burden on an already-strained healthcare system. Fortunately, there are interventions that help keep the brain sharp and nimble.

“Overall research findings support positive effects of cognitive and physical activity, social engagement, and therapeutic nutrition in optimizing cognitive aging,” wrote the authors of a literature review published in the Journal of Psychosocial Nursing and Mental Health Services.

The following are eight evidence-based lifestyle interventions that not only stave off cognitive decline but also boost cognitive faculties.

Eat healthy fats

Proper nutrition—in particular, lipid intake—impacts brain function and health, which affects emotions, cognitive functions, neuroendocrine function, behavior, and synaptic plasticity, as well as neuroprotection or detriment.

In a meta-analysis spanning 12 randomized-controlled trials, researchers found that low levels of omega-3 supplementation (<1.73 g/day) significantly reduced cognitive decline compared with placebo. Intriguingly, the same effect was not observed with higher levels of supplementation, so there’s probably no need to go overboard with omega-3 intake.

“The subanalysis suggests that low-dose but not higher-dose omega-3 supplementation has positive effects on cognitive function. This variation may in part explain the contrasting reports observed with clinical trials of omega-3 and cognitive function. However, what is important to note is the positive impact of low-dose omega-3 on memory,” the researchers wrote.

“The mechanism(s) of effect remains to be elucidated, but may include reducing the production of amyloid beta-protein, thus reducing the plaque burden on neuronal cells and ultimately preventing neuronal cell death. This in turn would prevent memory loss and/or reduce the speed of cognitive deterioration,” they concluded.

Solve puzzles

Some activities that stimulate cognition can be quite fun.

“Chess and bridge are leisure activities that demand working memory and reasoning skills,” wrote authors of the aforementioned literature review. “Older adults who play bridge score higher on working memory and reasoning measures compared to nonplayers and working crossword puzzles has also been associated with maintained cognition in older adults.”

The authors pointed out that although most correlational studies indicated benefits from cognitively demanding activities, more research needs to be done to suss out whether such activities truly contribute to better cognition.

Cultivate strong relationships

One familiar adage is “happy wife, happy life.” Unfortunately, there’s no similar saying for “happy husband.” (What rhymes with husband?) Nevertheless, married people seem to be healthier in certain contexts, including cognitive health.

In a systematic review and high-powered meta-analysis published in the Journal of Neurology, Neurosurgery & Psychiatry, researchers compared dementia risk in married people with those who are single, widowed, or divorced. They found that lifelong single people had a 42% increased risk of developing dementia and widowed people had a 20% higher risk compared with married people. No associations were observed in divorced people. Notably, decreased risk of dementia in married people remained after considering covariates.

The researchers had some ideas as to why married people have a lower risk of dementia. “Being married may change individuals’ exposure to other protective and risk factors throughout their subsequent lifespan; this is supported by our identification of confounding factors affecting this risk and evidence showing married people to be more likely to have a healthy lifestyle,” they wrote.

They also suggested the following: “Developing dementia could be related to other underlying cognitive or personality traits meaning that in societies where marriage was the social norm, people with difficulties in flexibility of thought or communication and consequent smaller lifelong cognitive reserve (therefore more likely to develop dementia) may be less likely to marry.”

Get out and garden

A growing corpus of research indicates that physical activity helps prevent cognitive decline and Alzheimer disease. Conversely, sedentary behavior heightens the risk of age-associated cognitive decline.  In fact, experts estimate that a 25% reduction in sedentary behavior could prevent more than 1 million cases of Alzheimer disease globally.

In a longitudinal study published in the Journal of Alzheimer’s Disease, other researchers evaluated the effect of caloric expenditure from gardening, mowing, and raking, as well as various types of exercise, on gray matter volumes in the elderly people with and without cognitive impairment. “In assessing physical activity, caloric expenditure is a proxy marker reflecting the sum total of multiple physical activity types conducted by an individual,” they noted. 

Using MRI, the researchers found that increased gray-matter volumes in the frontal, parietal, and temporal lobes, as well as the hippocampus, thalamus, and basal ganglia were linked to higher caloric expenditure. Moreover, higher levels of calorie expenditure mitigated neurodegenerative volume loss in the precuneus, posterior cingulate, and cerebellar vermis. In short, the more activity that older people do, the bigger their brains. 

Reduce stress

According to the authors of a study published in Science, stress affects brain function. “Chronic stress, mainly through the release of corticosteroids, affects executive behavior through sequential structural modulation of brain networks. Stress-induced deficits in spatial reference, working memory, and behavioral flexibility are associated with synaptic and dendritic reorganization in both the hippocampus and the medial prefrontal cortex,” they wrote.

Although there’s likely no surefire way to decrease stress, investigators publishing in the journal Frontiers in Behavioral Neuroscience found that writing about previous failures before taking a challenging 5-minute test attenuates stress responses.

“In a real-world setting, this information may be valuable to clinicians, as well as educators hoping to improve attentional performance,” they wrote. “Since writing about test anxieties has already been shown to protect against the negative effects of stress on performance on a high-stakes exam in a classroom setting, this writing manipulation may be especially valuable to populations who exhibit high levels of performance anxiety.”


In recent years, mindfulness has received a lot of attention. Mindful meditation practices (MMP) entail giving full attention to internal and external present-moment experiences and accepting emotional states in a nonjudgmental manner. Sounds pretty zen, right?

In the long term, MMP facilitates executive function and attention span. But even brief interventions seem to help. In a study published in Consciousness and Cognition, just a few sessions of MMP improved cognition when compared with a control group.

“After four sessions of either meditation training or listening to a recorded book, participants with no prior meditation experience were assessed with measures of mood, verbal fluency, visual coding, and working memory. Both interventions were effective at improving mood but only brief meditation training reduced fatigue, anxiety, and increased mindfulness,” researchers wrote.

“Moreover, brief mindfulness training significantly improved visuo-spatial processing, working memory, and executive functioning. Our findings suggest that 4 days of meditation training can enhance the ability to sustain attention; benefits that have previously been reported with long-term meditators,” they concluded.

Cut back on sugar

If the brain were a motor, then sugar could be considered its optimal fuel. But it’s easy to overdo it with sugar, especially with its abundance in Western diets. Excessive sugar intake is linked to both impaired memory and dementia risk. The WHO recommends that “free sugar” intake be limited to less than 10% of total caloric energy intake, with cutting back below 5% linked to even more health benefits.

Per the WHO: “Free sugars refer to monosaccharides (such as glucose, fructose) and disaccharides (such as sucrose or table sugar) added to foods and drinks by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates.”

However, this definition “does not refer to the sugars in fresh fruits and vegetables, and sugars naturally present in milk, because there is no reported evidence of adverse effects of consuming these sugars.”

The WHO stresses that sugars are often “hidden” in processed foods, so beware! For instance, 1 tablespoon of ketchup contains 4 g of free sugars, equivalent to about 1 teaspoon. Additionally, one can of sugar-sweetened soda may contain 40 g of sugar, a whopping 10 teaspoons!

Combine physical and cognitive exercises

In a society that seems to focus on physical training—including cardio and strength training—it’s easy to forget that other forms of exercise exist. There’s also motor training, which focuses on coordination, balance, and flexibility. 

While physical training activities are repetitive and automatic, thus demanding high energy output but low neuromuscular input, motor training is often the opposite (think Tai Chi). Nevertheless, there are exceptions like tennis, which burns a lot of calories and requires thought and coordination.

In a review article published in Frontiers in Medicine, the author recommends a mix of both physical and motor training to boost cognition in different ways.

“In the physical training category, it is the intensity of training that enhances neuroplasticity and consequently improves cognition, while in the motor activities it is the task complexity that increases neuroplasticity, which improves cognition. Dual-task training, which includes cognitive demands in addition to physical or motor activity, has proven more effective in improving cognitive functioning than a single task,” the author wrote. 

“The implications are that if all training components traditionally recommended by official bodies—physical as well as motor training—are efficient in enhancing cognition, then we merely have to emphasize the inclusion of all exercise modes in our routine exercise regimen for physical as well as cognitive health in advanced age,” she concluded.

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