This paper explores the multidimensionality of individual social capital by distinguishing between the effects of social support, social engagement, and societal trust on cognitive decline. The study focuses on Indonesian individuals aged 50 years and above, using data from the Indonesia Family Life Survey. Ordinary Least Squares regression is employed to determine vulnerable groups, while a moderating effect model is used to examine the role of social capital in buffering cognitive decline. This paper differentiates cognitive domains such as episodic memory, time orientation, numeracy, and verbal fluency. Evidence suggests that females, less educated, retired, and rural residents generally have lower cognitive function levels. However, the buffering impacts of social capital on cognitive domains are complex and vary among groups. For example, societal trust did not significantly affect the cognitive domains of females or the less educated but was significant for retirees' and rural residents' episodic memory. Social engagement buffered the verbal fluency of the less educated, while social support was crucial for their numeracy. Future research should explore these different moderating roles of social capital and consider community social capital to broaden intervention policy frameworks.