In a large sample followed for up to 22 years, we found those in the highest quartile of neuroticism (vs. the lowest quartile) or those in the lowest quartile of conscientiousness (vs. the highest quartile) were at a three-fold increased risk of incident AD. We further estimated that neuroticism and conscientiousness could account for 13% and 11% of the AD cases in the population, respectively. These effect sizes and PAR estimates are comparable to those reported for recognized clinical and lifestyle risk factors for AD, such as diabetes (RR = 1.39, 1.17–1.66; PAR = 3%), lower education (RR = 1.59, 1.35–1.86; PAR = 7%), smoking (RR = 1.59, 1.15–2.20; PAR = 11%), midlife obesity (RR = 1.60; 1.34–1.92; PAR = 7%), midlife hypertension (RR = 1.61; 1.16–2.24; PAR = 8%), physical inactivity (RR = 1.82; 1.19–2.78; PAR = 21%), or depression (RR = 1.90; 1.55–2.33; PAR = 15%).2 These findings indicate that personality traits may help identify individuals at greater risk of AD, and potentially aid in the early detection of AD.
