BBC News reports on a study that shows a link between depression and dementia:
Having depression may nearly double the risk of developing dementia later in life, new research suggests.
Experts know that the two conditions often co-exist, but it is not clear if one actually leads to the other.
Now two studies published in the American journal Neurology suggest depression does mean dementia is more likely, although they do not show why.
And the researchers stress that the findings merely reveal a link, not a direct cause.
They say more studies are needed to find out why the two conditions are linked.
They believe brain chemistry and lifestyle factors like diet and the amount of social time a person engages in may play a role.