Research from America suggests that deficiency of a particular B vitamin could play a role in dementia.
Scientists at the Agricultural Research Service, collaborating with peers from the University of California-Davis, started observing more than 1,800 Hispanic seniors since 1996.
It was found that those who were deficient in the B vitamin folate experienced higher levels of cognitive impairment - known symptoms of dementia.
Although less than one per cent of the observed population had this deficiency, the impairments were clearly detectable using standard cognitive function testing.
The research team also found that folate deficiency has a direct link to depression among women.
Female volunteers whose plasma levels were in the lowest third were twice as likely to have depression than those in the upper third.
Earlier this month, research from the British Medical Group suggested that B vitamin supplements offer "little to no benefit" for those looking to avoid a second stroke while recovering from the first.
Read more about Barchester's dementia care homes.