The effects of two Alzheimer's disease related genes APOE and MAPT in healthy young adults: An attentional blink study.

BACKGROUND: Genetic risk factors start to affect the brain and behavior in Alzheimer's disease (AD) before clinical symptoms occur. Although AD is mainly associated with memory deficits, attention and executive dysfunctions can present at the early presymptomatic stages in middle age for those with non-modifiable risks. OBJECTIVE: Here, we investigated whether known risk genes for AD already affected attention in young adulthood. METHODS: A total of 392 healthy young adults aged around 20 years underwent genetic testing for risks of dementia (APOE and MAPT) and performed a computerized cognitive test for temporal attention called the Attentional Blink (AB) task, in which patients with dementia tested in previous studies often showed reduced performance. Here, the AB task was analyzed using repeated-measurements analysis of variance for the ability of visual perception, attention deployment and temporal memory encoding/binding performance. RESULTS: The results showed that all participants exhibited AB effects. Importantly, genetic risk factors had statistically significant influence on temporal attention depending on sex in healthy young adults. APOE4 status was associated with enhanced attention deployment in males but not females, while MAPT AA carriers had poorer performance in AB but only in females. No genetic effects were found for visual perception and temporal memory binding errors between high and low risk groups. CONCLUSIONS: We provided evidence that both APOE and MAPT start to affect attentional function as early as young adulthood. Furthermore, unlike previous findings in older people, these genes had a differential effect for males and females in young adults.