The differential effects of type and frequency of social participation on IADL declines of older people.

Several types of SP have a favorable effect on IADL through moderate participation rather than frequent participation, and women with moderate participation in volunteer groups have a more beneficial effect on IADL than women with frequent participation. When advising community-dwelling older adults on SP for IADL maintenance, health professionals may need to take into account plateau effects, gender differences, and physical and mental functioning.