The prognosis of depression in old age: Good, bad or indifferent?

Depression has been described by Henry Brodaty as the ‘bread and butter’ of old age psychiatry. In four community surveys of old people depression outranked dementia in frequency by a factor of at least three to one (Copeland et al., 1987a and b; Livingstone et al., 1990), and depression is the commonest diagnosis among those aged 65-75 who present to psychiatrists (Post, 1982). After the landmark study of Roth (1955) affective disorders in the elderly were regarded as having a relatively good prognosis, but this comforting dictum was undermined by the worrying finding of Murphy (1983) that only 35 per cent of 124 subjects treated for a first depression in old age were well one year after presentation. Many old age psychiatrists felt that these findings were at variance with their own practice, and at least two set out to refute them (Baldwin and Jolley, 1986), but eight years after the publication of Murphy’s study there are plenty of unanswered questions regarding the prognosis of depression in old age. It is important to have accurate data regarding the prognosis of common disorders under current treatment regimes. Patients and their relatives are entitled to accurate statements about likely outcome. Factors associated with good and poor outcomes may point to ways to prevent the disorder under consideration or improve its management, and unless we know the prognosis of a condition as currently managed, we cannot tell whether putative improvements in treatment and care are effective in improving outcome. Without accurate research data clinicians tend to fall back on clinical impression to form views of the likely outcomes of treated disorder in individual patients. Judgement heuristics and biases (cognitive short cuts used to make quick approximate judgements) have a tendency to cause errors in probability judgements which violate statistical laws in predictable ways (Schwartz and Griffin, 1986). Subjective probability estimates are partly determined by the ease with which events similar to those under consideration can be brought to mind, the so called availability heuristic. The salience of particular cases makes them easier to retrieve from the memory than others, and it may be that clinicians find successfully treated cases more salient because of the greater satisfaction inherent in the management of such patients. Normal people tend to emphasize positive events in their memories and psychiatrists are likely to prove no exception to this rule. This might help to explain the general surprise at Murphy’s findings, and account for her interesting observation that optimistic case-note entries were often at marked variance with the findings of structured follow-up interviews conducted by a clinician who was not involved with the treating team. The views of clinicians are a useful hypothesis generating mechanism, but hypothesis testing requires research to distinguish between those things everybody knows to be true, which are true, and those things everybody knows to be true which are false! Since the advent of electroconvulsive treatment and antidepressant drugs it has been considered unethical to conduct long-term outcome studies on untreated individuals with depressive illness.