Giving a new turn to the Confucian ideal of filial piety, the research found that the assistance of daughters-in-law - but not their own children - helps mitigate depression among older people in China.
This is particularly true in rural areas, where elders may rely more heavily on family to be support providers, the study added.
"The inability to secure assistance from children may induce depression not only because needs are likely to go unmet but because the absence of such support may induce feelings of helplessness and strain intergenerational relations," says Zhen Cong, who received her Ph.D. in May 2008 from the USC Davis School of Gerontology.
Cong and Professor Merril Silverstein of the USC Davis School of Gerontology were intrigued by earlier findings showing that intergenerational support, particularly hands-on care, had inconsistent effects on the psychological well-being of Chinese elders.
Unlike emotional and financial support, instrumental support-in spite of its apparent cultural and practical significance-has shown inconsistent effects on the psychological well-being," says Silverstein.
The researchers looked at rural Anhui province, where rates of depression are twice that of their urban counterparts (though still much lower than in the West).
They found that "instrumental support" - such as personal care and household chores - had a positive effect on well being, depending on who was providing the service.
When women shared a home with their in-laws, their presence and support was particularly beneficial to the psychological well being of older mothers. Daughters-in-law provided the overwhelming majority of personal care for older women in a household, the researchers found.
However, household support and personal care from sons was particularly damaging and increased depressive symptoms, according to the study, appearing in the August 2008 issue of the Journal of Marriage and Family.
Similarly, mothers who received an increase in household support from daughters-in-law had fewer depressive symptoms, while those who experienced an increase in household support from their own daughters had more depressive symptoms.