Digital Clock Drawing as an Alzheimer's Disease Susceptibility Biomarker: Associations with Genetic Risk Score and APOE in Older Adults.

BACKGROUND: Alzheimer's disease (AD) is the leading cause of dementia in older adults, but most people are not diagnosed until significant neuronal loss has likely occurred along with a decline in cognition. Non-invasive and cost-effective digital biomarkers for AD have the potential to improve early detection. OBJECTIVE: We examined the validity of DCTclockTM (a digitized clock drawing task) as an AD susceptibility biomarker. DESIGN: We used two primary independent variables, Apolipoprotein E (APOE) ε4 allele carrier status and polygenic risk score (PRS). We examined APOE and PRS associations with DCTclockTM composite scores as dependent measures. SETTING: We used existing data from the Framingham Heart Study (FHS), a community-based study with the largest dataset of digital clock drawing data to date. PARTICIPANTS: The sample consisted of 2,398 older adults ages 60-94 with DCTclockTM data (mean age of 72.3, 55% female and 92% White). MEASUREMENTS: PRS was calculated using 38 variants identified in a recent large genome-wide association study (GWAS) and meta-analysis of late-onset AD (LOAD). RESULTS: Results showed that DCTclockTM performance decreased with advancing age, lower education, and the presence of one or more copies of APOE ε4. Lower DCTclockTM Total Score as well as lower composite scores for Information Processing Speed (both command and copy conditions) and Drawing Efficiency (command condition) were significantly associated with higher PRS levels and more copies of APOE ε4. APOE and PRS associations displayed similar effect sizes in both men and women. CONCLUSIONS: Our results indicate that higher AD genetic risk is associated with poorer DCTclockTM performance in older adults without dementia. This is the first study to demonstrate significant differences in clock drawing performance on the basis of APOE status or PRS.

The Effects of Subjective Cognitive Decline on APOE Genotype Disclosure in the Butler Hospital Alzheimer's Prevention Registry.

BACKGROUND: Subjective cognitive decline (SCD) and APOE genotyping are both instrumental in identifying high-risk individuals for Alzheimer's disease (AD) prevention trials. OBJECTIVE: This study examined the relationship between SCD and the impact of APOE disclosure on the psychological and behavioral health of cognitively unimpaired individuals. Design/Setting/Participant: We recruited 189 trial volunteers (mean age 66, 65% female, 96% White), from the Butler Hospital Alzheimer's Prevention Registry. Participants completed screening for cognitive impairment and a psychological readiness assessment before learning their APOE genotype, and were followed for 6 months after. RESULTS: SCD had a modest, temporary impact on mood and event-related distress following APOE disclosure, specifically on those who were ε4 carriers. The presence of SCD (SCD+) did not compound the AD genetic test-specific distress related to learning that one was an ε4 carrier. SCD also did not moderate changes in perceived AD risk, with all non-carriers showing a more rapid decrease in perceived risk over time than carriers. Counterintuitively, those without SCD (SCD-) reported taking more steps in future-directives than the SCD+ group at baseline and after disclosure, potentially suggesting that those with SCD may have subtle executive declines that limit future-oriented actions or fear-avoidance behaviors. Further, the SCD- group was more accurate in recalling their APOE status and the recall accuracy correlated with their broad knowledge about APOE as a risk gene for AD. CONCLUSION: Our findings support the safety and tolerability of APOE disclosure in research volunteers regardless of their SCD statuses, but further studies are warranted to include diverse individuals and those pursuing testing through direct-to-consumer services outside of traditional research settings.