The South African Indian population has, apart from easily distinguished recent migrants, been in the country for 100+ years, and is relatively large (more than 1 million people). Due to apartheid, assimilation was limited, and the population was drawn from all over India. It would make an interesting comparison group, matched for socioeconomic status. If the pattern persisted in South Africa, then further research would be needed - South African Indians generally rely on pensions/savings to support them in old age.