Amongst the oldest old (85-plus), depression is frequent and highly persistent, according to a new study from The Netherlands.

Despite its negative consequences, little is known about the natural history of depression in the oldest old. This study, published in the January 2006 issue of the British Journal of Psychiatry, examined the incidence, course and predictors of depression in the general population of people aged over 85.

The Leiden 85-plus Study is a population-based prospective study of a large number of community-dwelling older adults living in Leiden in The Netherlands. Between 1997 and 1999 all those born in 1912-1914 were enrolled in the month of their 85th birthday.

At the beginning of the study, 500 participants were visited by medical staff and research nurses. During these baseline visits, face-to-face interviews were carried out, an electrocardiogram was recorded and blood samples collected.

Follow-up interviews using the Geriatric Depression Scale were carried out for all eligible participants each year during the study period of four years.

It was found that at baseline, 67% of those studied had no significant symptoms of depression. During follow-up, however, the average depression score increased significantly up to the age of 89, and the annual risk for the emergence of depression was 6.8%.

Institutionalisation and poor daily functioning were associated with an increased risk of the development of depression.

Among the 77 participants with depression at baseline, the annual remission rate was only 14%. In more than half of the patients with a remission of depression, the researchers observed a relapse of depression during follow-up. No predictors of remission could be identified.

The authors of the study comment that a strong tendency for chronic depression has been reported in the younger elderly. Persistence of depression could be extrapolated to the oldest old.

Cognitive impairment or early-stage dementia may well play an important role in the high incidence of depression and its persistence in the oldest old, but the underlying mechanisms are still unresolved.

From a clinical perspective it is very important to know that depression occurs often in this age group, and has a poor prognosis. More active diagnosis and treatment of depression is needed, as treatment of depression in the oldest old is potentially as rewarding as in younger people.

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