A study investigated whether a healthy lifestyle is associated with lower risk of dementia, regardless of genetic risk.
The retrospective cohort study included 196,383 participants of European ancestry aged at least 60 years without dementia at baseline. Participants were given a polygenic risk score for dementia with low (lowest quintile), intermediate (quintiles 2 to 4), and high (highest quintile) risk categories and a weighted healthy lifestyle score categorised into favourable, intermediate, and unfavourable lifestyles. Favourable lifesyle was characterised by no current smoking, regular physical activity, healthy diet, and moderate alcohol consumption.
Overall, 68.1% of participants followed a favourable lifestyle, 23.6% an intermediate lifestyle, and 8.2% an unfavourable lifestyle. 20% had high polygenic risk scores, 60% had intermediate risk scores, and 20% had low risk scores.
Of the participants with high genetic risk, 1.23% developed dementia compared with 0.63% of the participants with low genetic risk. Of the participants with a high genetic risk and unfavourable lifestyle, 1.78% developed dementia compared with 0.56% of participants with low genetic risk and favourable lifestyle.
Participants with a high genetic risk and unfavourable lifestyle score had a statistically significant hazard ratio for incident all-cause dementia of 2.83 compared with participants with a low genetic risk and favourable lifestyle score. The study findings suggest that a favourable lifestyle was associated with a lower risk of dementia, but no significant interaction between genetic risk and healthy lifestyle.
Source: Association of Lifestyle and Genetic Risk with Incidence of Dementia. I Lourida; E Hannon; T J Littlejohns; et al Kenneth M. Langa; E Hyppönen; E Ku?ma; DJ Llewellyn JAMA. Published online July 14, 2019.