Overall, the authors found no relationship between social interaction and cognitive decline. However, when they delved into the beta-amyloid data, a pattern formed.
The researchers found that the influence of social activity was significant in individuals who had the highest levels of beta-amyloid in their brains. In this group, those with the lowest levels of social interaction showed higher levels of cognitive decline than individuals with similar levels of beta-amyloid but greater levels of social activity.
They also found that individuals who had lower cognitive abilities at the start of the study were more likely to become less socially engaged over the 3 years.