Cognitive Decline Risk Factors in Aging Populations

Cognitive decline in later life arises from an interplay of genetic predisposition, vascular and metabolic burden, lifestyle exposures and environmental factors. Genetic variants such as the apolipoprotein E ε4 allele confer elevated risk for Alzheimer’s pathology, while polygenic risk scores capture the aggregate effect of multiple loci. Vascular risk factors – including hypertension, diabetes, dyslipidaemia and obesity – drive cerebrovascular damage and promote neurodegenerative cascades. Metabolic syndrome and sustained hyperglycaemia exacerbate oxidative stress, impair mitochondrial function and accelerate synaptic loss. Lifestyle behaviours across the life course, from mid-life physical inactivity, poor diet and excessive alcohol intake to cumulative tobacco exposure and secondhand smoke, further influence brain resilience. Cognitive reserve, built through education, occupation and social engagement, may attenuate or delay clinical manifestations. Socioeconomic disparities and environmental pollutants also modulate risk, particularly in populations lacking preventive care. Globally, these factors underpin divergent trajectories of ageing and inform public health strategies to mitigate burden. Emerging evidence highlights that risk accumulation in mid-life magnifies late-life decline, yet early modification of lifestyle and management of vascular health can substantially reduce incidence of dementia. A comprehensive approach addressing genetic susceptibility, vascular health and lifestyle interventions is essential to preserve cognitive function and promote healthy ageing.

Research from Nature Portfolio

A large Spanish cohort study assessed cumulative smoking exposure in over 2,600 older adults using pack-year metrics and demonstrated a dose-dependent relationship between higher pack-years and decline on a detailed cognitive screening scale over three years. Findings confirmed that even moderate long-term smoking accelerates cognitive deterioration in non-demented seniors. In a UK Biobank analysis, investigators probed interactions between cigarette smoking, polygenic risk and apolipoprotein E genotype in nearly 200,000 participants. Results revealed that smoking increased dementia risk primarily among non-ε4 carriers, suggesting that genetic predisposition modulates the impact of tobacco on neurodegeneration. Another study using web-based cognitive assessments identified sex-specific effects of smoking and vascular disease on verbal learning and memory, finding that smoking was more strongly linked with poorer performance in women across adulthood, whereas cardiovascular burden influenced men’s outcomes. Together, these studies elucidate how tobacco interacts with genetic risk and sex to shape cognitive trajectories and underscore the value of personalised prevention strategies.

Cognitive Decline Risk Factors in Aging Populations publication trend

The graph below shows the total number of articles in cognitive decline risk factors in aging populations across all publications each year (not limited to Nature Index journals).

Technical terms

Pack-years: A measure of cumulative tobacco exposure, defined as the number of cigarette packs smoked per day multiplied by years of smoking.

Apolipoprotein E ε4 allele: A variant of the APOE gene associated with increased risk of Alzheimer’s disease and poorer outcomes in cognitive ageing.

Polygenic risk: Aggregated risk estimate derived from multiple genetic variants across the genome, excluding major loci such as APOE.

Metabolic syndrome: A cluster of conditions – including central obesity, hypertension, dyslipidaemia and insulin resistance – that elevate risk for cardiovascular disease and cognitive decline.

Cognitive reserve: The brain’s resilience capacity to compensate for neuropathological damage through efficient or alternative neural networks, influenced by education and life experiences.

References

1. Association between cumulative smoking exposure and cognitive decline in non-demented older adults: NEDICES study. Scientific Reports (2023).
2. Interaction between genetic predisposition, smoking, and dementia risk: a population-based cohort study. Scientific Reports (2021).
3. Smoking is associated with impaired verbal learning and memory performance in women more than men. Scientific Reports (2021).
4. Time trends in Alzheimer’s disease mortality attributable to metabolic risks and smoking in China from 1990 to 2019: an age-period-cohort analysis. Frontiers in Aging Neuroscience (2024).
5. Association between cardiovascular risk factors and cognitive impairment in adults aged 60 years or older from Chile: a cross-sectional study. BMC Geriatrics (2023).
6. Higher blood cotinine level is associated with worse cognitive functioning in non-smoking older adults. Frontiers in Neuroscience (2022).