How big a factor is lifestyle in Alzheimer’s disease?

Should preventive, diagnostic and treatment strategies be applied at individual or societal level?

According to the Dementia Services Information and Development Centre (DSiDC), at St James’s Hospital, the cost of dementia to the State is estimated at €1.69 billion per annum.

But should preventive, diagnostic and treatment strategies be applied at an individual or societal level?

In April, 2022, a British Medical Journal study (BMJ) of 2,449 men and women aged 65 years and older concluded that healthy lifestyles — improved diet, cognitive activities and exercise; less smoking and alcohol consumption — “could increase life expectancy among men and women … [and might] … increase the proportion of remaining years lived without Alzheimer’s dementia.” The most common form of dementia is Alzheimer’s disease (AD), contributing to the majority of all cases.

Dr Timothy Daly — an Irish-British researcher working on ethics and AD at the Sorbonne, Paris — favours looking beyond lifestyle to prevent dementia, despite the study’s “encouraging finding that older people with virtue [healthy diet, cognitive and physical activity] and without vice [non-smoking, low alcohol intake] have longer life expectancy and more dementia-free years.” The BMJ study, says Daly, ignores “the robust wealth-brain health link, despite socioeconomic deprivation increasing dementia risk independently of lifestyle while also reducing participation in healthy lifestyle activities”, with individualistic lifestyle-only approaches overlooking the need for societal structural changes contributing to a whole- population approach to dementia.


Provide access to quality education, ideally into early adult life, since the brain matures into one’s 20s

Daly told The Irish Times of a health social gradient, where socioeconomically deprived people are less healthy. “Dementia is no exception,” he argues, “both in accessing diagnosis and care and for the lifetime risk of developing dementia. Early educational access and fewer environmental stressors, like excess noise and air pollution, can confer increased resistance to dementia later in life.” Early life, he explains, “leaves a lifelong imprint on your brain, but not everyone benefits from the environment they grow up and work in”.

How might Daly’s approach be realised? First, “provide access to quality education, ideally into early adult life, since the brain matures into one’s 20s. Women with dementia,” he adds, “outnumber men two to one, and historically have had less educational access, so it’s important they accumulate brain capital early in life through quality education. Second, provide access to physically, mentally, and socially stimulating environments like green spaces, and promote campaigns against later-life loneliness.”

Public policy to reduce dementia risk, argues Daly, “involves changing behaviours, but government initiatives encouraging change are ethically obliged to accompany these campaigns with structural changes, making healthy living feasible for families and communities. This means providing better schooling, healthier food, and richer environments across society.”

However, Dr Louise Hopper — an assistant psychologist at Dublin City University’s School of Psychology — dislikes Daly’s virtue-vice framework to illustrate lifestyle risk factors, telling The Irish Times that “at an individual level, research shows that a healthy and varied lifestyle benefits life expectancy generally, and protects against the risk of developing dementia, specifically encouraging healthy lifestyles at an individual level [and] demonstrates that individuals have some control over their health, and those with less-than-ideal lifestyles shouldn’t be demonised.”

Areas of inequity in our society, she observes, “include education, health, diet, and employment, but with increasing knowledge it’s reasonable to impart such information to people in a truthful and factual way. We should invest in raising health and data literacy levels so that the information can be understood, particularly in the current post-truth environment. So, individual interventions and those aimed towards at-risk populations are one part of the dementia prevention puzzle.”

Suggesting that dementia prevention is more than an individual approach versus a whole-population approach, Hopper cites Bronfenbrenner’s Ecological Systems Theory whereby communities bridge the gap between individual interventions and public health policy. “For example, community gardens connect people to what they’re producing and what they’re eating, while promoting socialisation. So, it’s about diverse initiatives coming together at different levels.”

Daly asserts that we have transposed our generally individualist and capitalist outlook of economic success to the domain of health

It is arguable that contemporary public health focuses more on reducing lifestyle risk factors for chronic disease such as AD, thus embodying a tendency to moralise about health and behaviour and usurping medicine’s assumed neutrality. How relevant are such concerns? Hopper argues that at a time of constrained healthcare resources, the moralising aspect of health education “needs to be considered carefully. If people are accountable for their own choices, should that influence the healthcare they receive? Perhaps the answer to this question already influences healthcare decisions, with some of these decisions already being made unconsciously or explicitly, or even raised using different language like ‘who is this intervention likely to benefit more?’”

Daly asserts that we have transposed our generally individualist and capitalist outlook of economic success to the domain of health. “If you’re fit and healthy, it’s because of your own efforts. The flip side is that people get blamed for their bad health. This leads us to overlook the kind of public health impact we could have if we were to make our unequal society fairer.”

Daly and Hopper agree that AD should be seen as a chronic disease, and Daly notes “some promising data from epidemiology suggesting that rates of dementia are dropping because of changes in society like improved overall health. We should go further with a population-based approach that ensures better education, better diet, and better environments throughout society.” However, Hopper underlines the importance of policymakers considering the nature of equity. “It’s not about equality and giving the same to everyone, like deducting €100 euro off everyone’s electric bill. Real equity entails giving €500 to those who need it, and €10 euro or zero euro to those who don’t.”

Perhaps acknowledging tensions between individual responsibilities and societal obligations is a prerequisite to the effective prevention and treatment of AD.