Perimenopausal women face a perfect storm of hormonal changes and life transitions that make cognitive health particularly vulnerable. New findings reveal that social disconnection during this critical period creates compounding risks that extend far beyond what either loneliness or isolation might cause alone. Among 903 women navigating perimenopause, researchers identified that loneliness and social isolation operate as independent risk factors for subjective cognitive decline, with over half experiencing severe symptoms. The study employed latent class analysis to distinguish mild versus severe cognitive decline patterns, finding that women experiencing both moderate-to-severe loneliness and social isolation showed the highest probability of severe cognitive symptoms. Crucially, the analysis revealed both additive and multiplicative interactions between these social factors, meaning their combined impact exceeds the sum of their individual effects. This suggests that socially isolated women who also feel lonely experience a synergistic deterioration in cognitive function. The timing is particularly significant given that perimenopause already involves hormonal fluctuations affecting memory and concentration. These findings challenge the common assumption that cognitive changes during perimenopause are primarily biological inevitabilities. Instead, they suggest that social connection serves as a modifiable protective factor during this vulnerable transition. For the millions of women entering perimenopause, this research highlights how maintaining both objective social networks and subjective feelings of connection may be as important as addressing hormonal changes. The multiplicative interaction pattern suggests that interventions targeting either loneliness or isolation alone may prove insufficient—comprehensive approaches addressing both dimensions of social disconnection appear necessary for optimal cognitive preservation during this critical life stage.