Thursday, May 7, 2009

Consensus Statement on Depression

This is a consensus statement on what to do about depression in Canada.
It is the summary output of a conference that was held last year.
The report is not just an academic report, it had lots of diverse input.

You can get a copy of the report here.

Is Depression Much More Common than Experts Think?

Standardized interviews to detect depression have been available since the 1980s. In order to determine the prevalence of major depression, most studies have adminstered these interviews to samples of people in the community. There is, however, a potentially serious problem with this approach. Not all episodes of depression are necessarily remembered. Furthermore, the instruments attempt to identifiy episodes by asking about specific symptoms, but people may not remember, for example, a series of weeks during which their sleep or appetite patterns were altered. Furthermore, of course, peoples' memories of events can change over time. The end result is that the prevalence of major depression in the population may be seriously underestimated. To explore this possibility, I recently examined the accumulation of depressive episodes during 14 years of follow-up in the National Population Health Survey. Since the participants in this cohort were interviewed every two years, they were probably much more likely to have episodes detected than other studies where they have been asked to recall episodes occuring much earlier in their life.

The hypothesis was confimed: the prevalence of depression as measured by the prospective approach was twice the usually cited figures for Canada. Major depression is probably much more common than is currently beleived. Details (in preliminary form) may be found here in the journal BMC Psychiatry.

Depression and Participation in Preventive Health Care Activities

Prevention plays an important role in health care. Monitoring blood pressure is a way to detect elevated blood pressure and by treating this prevent strokes and heart disease. Procedures such as mammography and Pap tests can detect cancers earlier than they would normally be detected and at a stage when they are more likely to be curable. When people are struggling with depression they may be less likely to persevere with these kinds of preventive activities. Even mild depression can affect peoples' energy and motivation, which could have an impact. Also, while depressed, it is more difficult for people to think positively - and preventive health care is all about creating a healthier future. Finally, when people are severely depressed they may not value their life as much (the most extreme such manifestation being suicidality) and therefore not take steps to safeguard it.

Because of these concerns, we have examined the impact of major depression on participation in preventive health care activities in Canadians during the late 1990s and up to 2004. The results are available here. Surprisingly, no effect was found. The most likely explanation is that even though depression might cause reduced participation, this is offset by more frequenty contact with the health system. People with depression contact the health system more often because they are seeking or receiving treatment, and perhaps for other reasons as well (e.g. a tendency of depression to magnify pain complaints).