Sometimes, Kristine Yaffe encounters a striking question in her memory clinic: “I walk five miles a day, don’t drink, and play bridge,” someone might ask, “so why do I have Alzheimer’s disease?”
Yaffe, a neurologist and dementia expert at the University of California, San Francisco, finds it tough to explain that even with lifestyle changes aimed at reducing dementia risk, there’s no foolproof way to avoid the condition.
This struggle reflects a broader challenge in the field. Research has found a number of lifestyle choices believed to lower dementia risks, like maintaining a healthy diet, engaging in regular exercise, and participating in social and cognitive activities. Some less obvious factors also appear relevant, such as addressing vision and hearing impairments and possibly even getting a shingles vaccine. However, determining how much these factors truly impact risk reduction in real-life scenarios remains complex.
Despite extensive attempts, understanding the effects of lifestyle changes hasn’t been straightforward. There are several ambitious clinical trials underway, testing the impact of interventions that aim to enhance diet, exercise, social connections, and both heart and brain health. For example, the FINGER trial took place in Finland and involved approximately 2,650 participants undergoing a two-year lifestyle transformation. There’s also the POINTER study, which pursued a similar approach in the United States. While such research suggests that these lifestyle programs may enhance cognitive performance, the impacts seem limited — only a slight advantage on certain memory tests has been noted, and no trial has conclusively reduced dementia incidence. Critiques arise questioning the cost and scalability of such programs.
Several upcoming studies, including offshoots from FINGER in the Netherlands and twelve Latin American nations, are set to report results soon. Furthermore, the World Health Organization is preparing to release updated guidelines on reducing dementia risk. Finding the most effective approaches is crucial for researchers, health practitioners, and the general public, especially as global dementia rates are expected to rise sharply in the coming decades.
Some experts express skepticism about the effectiveness of lifestyle interventions, while others argue that even a minor delay in cognitive decline justifies the effort. Another concern arises regarding an overemphasis on individual responsibility for dementia risk, given that significant risk factors like air pollution, educational access, and the availability of nutritious food often lie beyond personal control. Edo Richard, a neurologist from Radboud University Medical Center in the Netherlands, stated, “This is a societal issue… I think we’ve concentrated too heavily on individual lifestyle choices.”
Difficult calculations
Currently, 57 million people are living with dementia, a figure that could swell to 153 million by 2050, according to the Global Burden of Disease Study. Over 60% of those affected are in low- to middle-income nations, where the rising burden is partly due to increased life expectancy.
The most thorough evidence on dementia risk factors comes from the Lancet Commission, convened back in 2015. “It’s really become the definitive source,” claims Henry Brodaty, a dementia researcher at the Centre for Healthy Brain Ageing at the University of New South Wales, Australia.
The Commission’s recent 2024 report identified 14 modifiable risk factors, such as inadequate physical activity, high blood pressure, obesity, diabetes, smoking, depression, traumatic brain injury, air pollution, low levels of education, social isolation, hearing impairment, untreated vision impairment, high levels of LDL cholesterol, and excessive alcohol consumption. Their calculations suggest that theoretically, 45% of dementia cases worldwide could be prevented through these modifications.
This estimate is based on population data, meaning an individual trying to address all these factors won’t necessarily lower their personal risk by that same percentage. Factors like physical inactivity or high alcohol consumption might have accumulated over many years, and it’s unclear if changing those habits later in life can reverse any existing harm.
Additionally, evidence suggests changing personal health behaviors can be very challenging. “It’s tough to get people to change their lifestyles, especially if they’re trying to prevent risks that may take decades to materialize,” Richard explains.
However, for the last couple of decades, researchers have been investigating the potential of lifestyle changes. In 2009, Finnish scientists started the FINGER study, a randomized controlled trial to see whether significant lifestyle improvements could mitigate cognitive decline and dementia risk. Finland has a background of running influential lifestyle trials aimed at reducing heart disease and diabetes risks, providing a solid foundation.
Led by Miia Kivipelto, a clinical geriatrician, the FINGER team involved participants aged 60 to 77, some with identified risk factors for dementia, randomly assigning them into intervention or control groups.
Over two years, the intervention group participated in various health sessions. Nutritionists assisted with dietary improvements, while physiotherapists guided tailored exercise regimens. Participants received cognitive training through computer activities and regular consultations with medical experts to monitor health metrics. The control group only received standard health advice.
The researchers assessed how the ‘multidomain lifestyle intervention’ impacted participants’ performances on standardized neuropsychological tests measuring memory and processing speed. The primary focus was on changes in their ‘Z score’, which indicates performance in standard deviation units. An increase of one in the Z score translates to a significant improvement.
The results, published in 2015, indicated that after two years, the intervention group’s average Z score increased by 0.20, while the control group saw an increase of 0.16. “It was quite surprising that both groups improved,” noted Alina Solomon, a neuroepidemiologist involved in the study. The increases could stem from participants getting more familiar with the cognitive tests during the trial.
Interpreting these outcomes is quite complex. The intervention group showed an improvement of only 0.04 more than the control group. While statistically significant, some argue this may represent a negligible difference. Kivipelto acknowledges the effect was modest but points out that many new Alzheimer’s treatments have shown similarly small enhancements in cognitive function. “In our area, effects on brain health and dementia are frequently subtle,” she comments.
Nonetheless, some critics describe the effect size as “very small” or “tiny”. One interpretation of the 0.04 improvement is that there’s about a 54% chance that a randomly chosen participant from the intervention group would perform better on cognitive assessments than someone chosen from the control group, which is a slight edge over the 50% mark if the intervention had no impact at all.
Fingers extending
Several other trials have examined similar interventions with varied and modest outcomes. In 2017, Kivipelto established the World-Wide FINGERS network, which now includes teams across 73 countries. “In large-scale studies with sufficiently intensive interventions, we consistently observe slight yet significant effects,” points out Mariagnese Barbera, scientific coordinator for FINGER at the University of Eastern Finland.
A recent trial that gained attention was the POINTER study, testing the FINGER model in the United States. Approximately 2,000 individuals aged 60 to 79 at risk for dementia were divided randomly into two groups. One received structured interventions, with 38 meetings focused on enhancing exercise, diet, cognitive function, and overall cardiovascular health. The control group received a less detailed, self-directed program with only six meetings.
Once again, both cohorts improved in cognitive tests, with the structured intervention group showing a marginally greater improvement. Researchers compared the results of the intensive group against the typical cognitive decline expected for their age and estimated it effectively slowed cognitive aging by one to two years.
However, skepticism surrounds the POINTER team’s claims regarding the perceived slowing of cognitive aging. With such minor differences, one might argue, “another interpretation is that neither approach yielded significant results,” according to Yaffe, who led a personalized intervention study known as SMARRT with about 170 participants, which also noted only modest cognitive improvements.
