Impact of learning APOE genotype on cognitively unimpaired adults: a pre-screening cohort study of the Alzheimer's Prevention Initiative Generation Study 1.

backgroundThe apolipoprotein E (APOE) gene is the best established genetic risk factor for Alzheimer's disease in later life, with the ε4 allele conferring higher risk. APOE disclosure is becoming increasingly common in the clinical care of people with Alzheimer's disease and in cognitively unimpaired adults. In this study, we aimed to describe changes in measures of genetic disease knowledge and psychiatric symptoms following APOE disclosure to cognitively unimpaired adults.

methodsData were collected as part of the screening phase of the global, multicentre, Alzheimer's Prevention Initiative Generation Study 1 (NCT02565511). Eligible individuals were cognitively unimpaired (Mini-Mental State Exam total score ≥24), aged 60-75 years, and psychologically pre-screened for readiness (by measures of depressive symptoms and anxiety) to receive their APOE genotype from a health-care provider. Participants were assessed before disclosure, and 2-7 days, 6 weeks, 6 months, and 12 months after disclosure. Multivariable linear and ordinal logistic regressions were used to compare changes in genetic disease knowledge, anxiety, depression, and distress by APOE4 genotype status, adjusting for key covariates, with a focus on 2-7 days after disclosure. Multiple imputation by chained equations methods was used to account for missing outcome data.

findingsThe trial took place between Nov 30, 2015, and Sept 23, 2019. In total, 9496 participants (including 790 APOE4 homozygotes, 4869 heterozygotes, and 3837 non-carriers) learned their APOE genotype from a health-care provider as part of Generation Study 1 screening. 4038 (42·5%) participants were in the 65-69-year age group, 5790 (61·0%) were female, 3706 (39·0%) were male, and 8862 (93·3%) self-identified as White. Increase in genetic disease knowledge 2-7 days after disclosure was greater in APOE4 homozygotes (mean 1·19 [SD 3·95]) than in heterozygotes (0·78 [3·95], p=0·042) and non-carriers (0·29 [3·96], p=0·0002). Disease-specific distress 2-7 days after disclosure increased more in homozygotes (2·25 [6·42]) than in heterozygotes (0·53 [5·08], p<0·0001) and non-carriers (0·79 [4·95], p<0·0001). Levels of anxiety 2-7 days after disclosure increased in homozygotes (0·17 [2·95]) but decreased in heterozygotes (-0·67 [2·68], p<0·0001) and non-carriers (-0·66 [2·67], p<0·0001). There were no significant changes in depressive symptoms following disclosure for any APOE4 group. Notably, for all APOE4 groups, increases in distress and anxiety were small and did not reach predefined levels of clinical concern.

interpretationIn cognitively unimpaired, psychologically pre-screened adults, APOE disclosure by a trained health-care provider was generally safe and well tolerated, consistent with results from previous studies. To our knowledge, this is the largest study experience of APOE disclosure to date, especially for homozygotes, and is notable for the older age of participants compared with previous research. These results are timely and important given anticipated increases in APOE disclosure to guide clinical decision making once an Alzheimer's disease prevention treatment is approved for cognitively unimpaired adults or if patients' family members are interested in genetic testing. Scalable approaches for returning Alzheimer's disease risk information are critical to meeting anticipated demand. Results from this study may be useful to bolster clinical translatability of disclosure programmes.

fundingThe National Institute on Aging, Alzheimer's Association, Banner Alzheimer's Foundation, GHR Foundation, F-Prime Biomedical Research Initiative (FBRI), and Novartis Pharma.