RIVERSIDE, Calif. — Alzheimer’s disease is an awful form of dementia that impairs memory, thinking, and everyday functioning in elderly adults. Now, a new study shows a specific gene linked to the condition may begin affecting cognitive functioning much earlier in life, even before adulthood.
It’s already been well established that people who carry this protein creating gene, known as APOE4 allele, are up to three times more likely to develop Alzheimer’s. The gene is found in 15% of the population. According to researchers at the University of California, Riverside, individuals carrying the gene scored lower on IQ tests during childhood and adolescence compared to people without it. This negative impact on IQ seemed to be more prevalent in girls than boys.
For the study, the research team compiled and analyzed data from two previous studies consisting of 1,321 participants between the ages of 6 and 18. The gender ratio among participants was almost completely even, and each subject took three IQ tests between childhood and adolescence.
The results of the study showed that for each APOE4 allele gene an individual carries, their IQ score drops by 1.91 points. A person can only carry up to two APOE4 allele genes, but the data seems to indicate that each additional APOE4 allele multiplies the genes’ impairment of IQ. For each APOE4 allele present, girls scored three whole points lower on IQ tests, while boys scored .33 points lower. The data also pointed to reasoning as the main mental trait impacted by APOE4 allele.
While the differences in IQ seem fairly minimal at first consideration, researchers say that APOE4 allele’s impact on cognition likely only gets worse as carriers continue to age.
“Our results suggest that cognitive differences associated with APOE may emerge early and become magnified later in the life course, and if so, childhood represents a key period of intervention to invest in and boost reserves,” comments lead author Chandra Reynolds in a release.
The study is published in the journal Neurobiology of Aging.