A study of older adults shows how changing diet and increasing physical activity can reduce dementia risk, even if the person already has a diagnosis of cognitive decline.

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New research adds to the evidence that increasing activity levels may help offset cognitive decline.

Dementia describes a group of disorders characterized by difficulties in thinking, remembering, and reasoning. Alzheimer’s disease is the most common type of cognitive decline.

According to the Centers for Disease Control and Prevention (CDC), at least 5 million people live with Alzheimer’s disease and related dementias in the United States. As the population ages, experts expect this number to increase significantly.

Although scientists do not know the precise biological cause of Alzheimer’s disease, they know that some lifestyle factors increase a person’s risk of developing dementia.

These include smoking, alcohol consumption, diet, and physical inactivity. One study estimated that up to half of all Alzheimer’s disease cases worldwide may have links to certain lifestyle factors.

A new study, led by The Australian National University in Canberra, trialed a series of lifestyle interventions in people already experiencing cognitive decline. They wanted to see whether these changes could improve a person’s cognitive state and potentially reduce their risk of developing dementia.

They found that people who actively changed certain aspects of their lifestyle experienced significant improvements in their cognition. This suggests that making certain lifestyle changes could alter the course of cognitive decline and reduce a person’s risk of developing Alzheimer’s disease.

The Journal of the American Geriatrics Society published the study.

The study included 119 people aged 65 or over who had either subjective cognitive decline (SCD), which is the self-reported experience of confusion or memory loss, or mild cognitive impairment (MCI), which is a clinically diagnosed form of cognitive decline.

Doctors consider both as early symptoms of dementia, although not everybody with SCD or MCI will develop dementia.

The study, which is part of the Body, Brain, Life for Cognitive Decline (BBL-CD) trial, aimed to determine whether diet and activity levels can reduce the risk of dementia in people with cognitive decline.

The researchers split the cohort roughly in two. Over 8 weeks, one group (the active control group) completed online modules on dementia risk, including information on a Mediterranean diet. A 2020 study has shown that the Mediterranean diet can slow cognitive impairment, exercise, and cognitive engagement.

The intervention group completed the same online training and participated in practical activities, including meeting with a dietitian and exercise physiologist and completing brain training exercises.

By the end of the study, the intervention group’s cognition levels were significantly higher than that of the control group. The researchers measured this using several tools, including the Alzheimer’s Disease Assessment Scale Cognitive Subscale.

Exposure to lifestyle risk factors for Alzheimer’s disease — assessed using a risk index developed by the Australian National University — was also significantly lower in the intervention group at the 3-month follow up.

However, at the final follow-up (6 months), this was not the case. This suggests that individuals need to maintain these dietary and activity changes to see the continued benefit.

Overall, the study shows that people already experiencing cognitive decline can reduce their risk of developing dementia later in life. The fact that they can achieve this by employing relatively simple and cost effective lifestyle changes is especially promising.

“[W]ith the right intervention, people experiencing cognitive decline may retain sufficient neuroplasticity for their brain to ‘bounce back’ from decline.”

– Mitchell McMaster, lead study author and Ph.D. student at the Australian National University

This proof-of-concept study adds to the evidence that making certain lifestyle changes can boost cognition.

However, this study was relatively short, with a maximum follow up of just 6 months. The researchers say a follow-up trial with more participants and over a more extended period will be important to confirm these findings and demonstrate sustained cognition improvements.

The finding that people did not maintain a reduced risk of Alzheimer’s disease by the end of the study suggests that people may require booster sessions to ensure continued benefits.