This study aims to investigate the effect of informal care received from the children, understood as the instrumental component of social support, on the cognitive functioning of elderly parents. As the correlation between informal care and cognitive functioning is likely to be driven by reverse causality or unobserved heterogeneity, we use instrumental variables (IV) approach with the gender ratio of the children as an instrument for the amount of informal care that parents receive from their children. Results from the IV models on data from the Survey of Health, Ageing and Retirement in Europe highlight a significant negative effect of the amount of informal care provided by the children on cognitive functioning of themothers. This hints that too much support may result in passive behaviors of the elderly, which in turn is detrimental for their cognitive functioning.