Authors: Carol E. Franz, Sean N. Hatton, Michael J. Lyons, Olivia K. Puckett, Nathan Whitsell, William S. Kremen
Published: 2020-12-07
DOI: 10.1002/alz.046011
Source: Full article
AbstractBackgroundRecent studies have reported significant associations between modifiable lifestyle factors and dementia (Licher et al, 2019; Lourida et al, 2019). We sought to extend those findings by examining whether the effect of lifestyle on brain age, a possible risk factor for dementia, is moderated by one’s level of general cognitive ability (GCA). Additionally, we examined associations between brain aging and mild cognitive impairment (MCI).MethodAt mean age 68 (SD 2.6; range 61‐72), 356 participants from the Vietnam Era Twin Study of Aging (VETSA) underwent structural MRI which was used to create predicted brain age difference (PBAD) scores (Liem et al., 2017). MCI at age 68 was determined using Jak/Bondi criteria. At mean age 40 (SD 2.7; range 34‐44), a positive lifestyle index was created comprising three self‐reported behaviors: not smoking, ≤ moderate alcohol consumption, and high social engagement. GCA at mean age 20 was assessed with the Armed Forces Qualification Test. Linear mixed models included GCA, lifestyle and their interaction as IVs, and adjusted for age, ethnicity, APOE genotype, height, and family membership.ResultAge 20 GCA and age 40 lifestyle were significantly associated with PBAD [F=5.83; p=.02 and F=15.14; p<.001, respectively]. Having a higher GCA or more positive lifestyle behaviors predicted having less advanced brain age. The GCA‐lifestyle interaction was significant, indicating moderation. Having both lower GCA and few positive behaviors predicted having an older brain age relative to chronological age [F=5.00; p=. 03], but GCA made no difference when more positive behaviors were present (Figure 1). At age 68, non‐amnestic MCI participants had significantly more advanced brain aging compared with cognitively normal or amnestic MCI participants [F=3.10; p=.05].ConclusionRisk reduction remains a major component in the fight to prevent/delay dementia. Early positive lifestyle behaviors appeared to be protective against brain aging nearly three decades later for those with low or moderate GCA. High GCA appeared to be protective regardless of lifestyle behaviors. These results suggest that the negative effects of lifestyle start early, particularly for those who have lower cognitive reserve. Early intervention may help promote healthier brain aging and possibly delay dementia onset.