Stroke, dementia, depression: common risk factors to consider

What if three of the major neurological threats associated with aging—stroke, dementia, and late-onset depression—shared a common foundation of vulnerabilities? This is what researchers from Harvard and Massachusetts General Hospital in Boston explored in a systematic review, the results of which were published in the Journal of Neurology, Neurosurgery & Psychiatry.Their objective: to identify the modifiable risk factors that overlap between these three diseases and to quantify their overall impact on a composite endpoint, using beta coefficients weighted by disability-adjusted life years (DALYs).“We know that these three diseases share several underlying mechanisms, including cerebral small vessel disease (CSVD). Yet, prevention is still too often approached in silos,” explained the study’s lead author, neurologist Dr. Sanjula Singh. “Our goal was to identify the most impactful risk factors to build a more integrated prevention strategy.”He and fellow researchers reviewed 182 meta-analyses published between 2000 and 2023, focusing on modifiable risk factors associated with stroke, all forms of dementia, and depression at the end of life. Fifty-nine were selected for their methodological rigour and clinical relevance.Each risk factor was assessed according to its effect on disease incidence, expressed using standard epidemiological measures: the relative risk (RR), the odds ratio (OR), and the hazard ratio (HR). The authors then converted these values into beta coefficients (β), which represent the strength and direction of the association (positive values for risk factors, negative values for protective factors).But the originality of their approach lies in weighting the results using DALYs (disability-adjusted life years), a composite indicator combining years of life lost due to premature mortality and years lived with disability. Used here to weight the effect of factors according to the actual burden of each disease, they reflect the burden these diseases place on the global population: 5.57% of neurological DALYs for stroke, 1.26% for dementia, and 1.59% for late-onset depression. This approach thus makes it possible to estimate the relative impact of each factor on the overall neurocognitive burden associated with aging.Among the 17 modifiable risk factors associated with at least two of the three diseases, hypertension stands out clearly, with a normalized beta coefficient of 130. It is followed by severe renal insufficiency (101) and elevated fasting blood glucose, above 126 mg/dL (94). Next come smoking (91), sleep disorders (76), obesity (70), hearing loss (60), and depressive symptoms (57).Specific nutritional factors, such as high consumption of fruits, vegetables, or nuts, are also associated with modest but statistically significant protective effects.The study highlights that some of these factors are linked to well-known health behaviours—diet, physical activity, smoking—but that others, such as feelings of loneliness or a lack of purpose in life, are still largely overlooked in clinical prevention strategies.“Rather than targeting one disease at a time, we need to equip clinicians and patients to address common factors, with maximum benefits for the aging brain,” said another co-author, Dr. Jonathan Rosand. “This also means educating people early on about brain health: The brain doesn’t wait for retirement to age.”The researchers acknowledge certain limitations to their study: the lack of robust data on late-onset depression, the absence of modeling of interactions between factors, and the potential for reverse causality. However, they emphasize the operational value of their approach. By providing a comparative mapping of modifiable risk factors, their study could inform the development of clinical tools to help professionals prioritize cross-cutting interventions focused on healthy neurological longevity.This article has been translated from its original French and first appeared on our sister site Profession Santé.

Stroke, dementia, depression: common risk factors to consider

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