Modifying effects of race and ethnicity and APOE on the association of physical activity with risk of Alzheimer's disease and related dementias.

INTRODUCTION: We investigated whether the protective association of physical activity with risk of Alzheimer's disease and related dementias (ADRD) has genetic or behavioral variations. METHODS: In the Multiethnic Cohort, we analyzed moderate or vigorous physical activity (MVPA) reported at ages 45 to 75 among 88,047 participants in relation to 13,039 incident diagnoses of late-onset ADRD identified in Medicare claims (1999 to 2014), by five racial and ethnic groups, hours sitting, and in a subset (16%), apolipoprotein E (APOE) genotype. RESULTS: MVPA was inversely associated with ADRD (hazard ratio for ≥14 vs <2.5 hours/week: 0.83, 95% confidence interval [CI]: 0.76 to 0.90 in men; 0.88, 5% CI: 0.81 to 0.95 in women). The association was inverse in all racial and ethnic groups except Black participants (P-heterogeneity = 0.52), but stronger in individuals with lower levels of sitting duration or those who do not carry the APOE e4 risk allele. DISCUSSION: The different effects of physical activity by sitting duration and APOE genotype warrant further research.

Diet quality and all-cause and cancer-specific mortality in cancer survivors and non-cancer individuals: the Multiethnic Cohort Study.

PURPOSE: We examined post-diagnostic diet quality in relation to all-cause and cancer-specific mortality among adults diagnosed with invasive cancer between cohort entry (45-75 years) and their 10-year follow-up, in comparison with those without invasive cancer during that period, in the Multiethnic Cohort. METHODS: Data were from 70,045 African Americans, Native Hawaiians, Japanese Americans, Latinos, and Whites (6370 with cancer, 63,675 without cancer). Diet quality was measured by the Healthy Eating Index (HEI)-2015, the Alternative HEI-2010 (AHEI-2010), the alternate Mediterranean Diet (aMED), and the Dietary Approaches to Stop Hypertension (DASH) scores, using a food frequency questionnaire. Multivariable Cox models estimated the association of the dietary indexes at 10-year follow-up and changes since baseline with subsequent mortality. RESULTS: Post-diagnostic scores from all four indexes were associated with lower mortality: for the highest vs. lowest quartiles, hazard ratio (HR) for all-cause mortality was 0.74 (95% CI 0.67-0.82) for HEI-2015, 0.82 (0.74-0.92) for AHEI-2010, 0.74 (0.66-0.84) for aMED, and 0.82 (0.74-0.91) for DASH. The corresponding HRs for cancer mortality were 0.84 (0.71-1.00), 0.85 (0.71-1.00), 0.71 (0.59-0.85), and 0.84 (0.71-1.00). Compared to stable scores over 10 years (< 0.5 SD change), HR for all-cause mortality was 0.87 (0.79-0.97) for ≥ 1 SD increase in HEI-2015 and was 1.22 to 1.29 for ≥ 1 SD decrease in scores across the four indexes. These HRs were similar to those for participants without cancer. CONCLUSION: Post-diagnostic high-quality diet was related to lower all-cause and cancer mortality among adult cancer survivors, with risk reduction comparable to that among participants without cancer.

Racial and Ethnic Differences in the Population-Attributable Fractions of Alzheimer Disease and Related Dementias.

BACKGROUND AND OBJECTIVES: Previous studies estimated that modifiable risk factors explain up to 40% of the dementia cases in the United States and that this population-attributable fraction (PAF) differs by race and ethnicity-estimates of future impact based on the risk factor prevalence in contemporary surveys. The aim of this study was to determine the race-specific and ethnicity-specific PAF of late-onset Alzheimer disease and related dementias (ADRDs) based on the risk factor prevalence and associations observed on the same individuals within a prospective cohort. METHODS: Data were from Multiethnic Cohort Study participants (African American, Japanese American, Latino, Native Hawaiian, and White) enrolled in Medicare Fee-for-Service. We estimated the PAF based on the prevalence of risk factors at cohort baseline and their mutually adjusted association with subsequent ADRD incidence. Risk factors included low educational attainment and midlife exposures to low neighborhood socioeconomic status, unmarried status, history of hypertension, stroke, diabetes or heart disease, smoking, physical inactivity, short or long sleep duration, obesity, and low-quality diet, as well as APOE ε4 for a subset. RESULTS: Among 91,881 participants (mean age 59.3 at baseline, 55.0% female participants), 16,507 incident ADRD cases were identified from Medicare claims (1999-2016, mean follow-up 9.3 years). The PAF for nongenetic factors combined was similar in men (24.0% [95% CI 21.3-26.6]) and women (22.8% [20.3-25.2]) but varied across Japanese American (14.2% [11.1-17.2]), White (21.9% [19.0-24.7]), African American (27.8% [22.3-33.0]), Native Hawaiian (29.3% [21.0-36.7]), and Latino (33.3% [27.5-38.5]) groups. The combined PAF was attenuated when accounting for competing risk of death, in both men (10.4%) and women (13.9%) and across racial and ethnic groups (4.7%-25.5%). The combined PAF was also different by age at diagnosis and ADRD subtypes, higher for younger (65-74 years: 43.2%) than older (75-84 years: 32.4%; ≥85 years: 11.3%) diagnoses and higher for vascular or unspecified ADRD than for AD or Lewy body dementia. An additional PAF of 11.8% (9.9-13.6) was associated with APOE ε4, which together with nongenetic risk factors accounted for 30.6% (25.8-35.1) of ADRD. DISCUSSION: Known risk factors explained about a third of the ADRD cases but with unequal distributions across racial and ethnic groups.