Thursday, May 29, 2008

An Ounce Of Prevention

In medicine, therapeutic interventions tend to fall into one of three classes. Tertiary prevention means doing something to reduce the impact of symptoms in a disease that already exists. Secondary prevention is when you try to catch the disease at an earlier stage, either before symptoms develop or before they become severe. Routine blood pressure checks are an example of secondary prevention because blood pressure measurement catches hypertension (hopefully) before complications like stroke or heart disease develop. Finally, primary prevention is when you do something to keep the disease from starting to begin with. Routine pap smears are a primary preventive measure for cervical cancer---the idea is to catch abnormal cells before they transform into cancer.

So how does this all apply to psychiatry?

It's relevant because, unfortunately, in our specialty right now almost all interventions are tertiary interventions. We see patients after a disease has developed, when they are bothered enough by their symptoms (or their families or employers are bothered enough) to make them seek treatment. By the time they come to treatment they have often already experienced some type of morbidity, either in the form of time lost from work or impaired social functioning, or even impaired physical recovery as in the case of hospitalized medical patients with untreated depression.

There have been some secondary prevention efforts. Every October there is a national depression screening day, when health fairs offer evaluations for clinical depression in addition to other general medical assessments. Internists, family practitioners and other primary care providers are starting to include screening for mental disorders as part of routine health care.

The area where psychiatry is still grossly lacking, mainly because of our still-meager understanding of the basic causes of mental illness, is in primary prevention. Simply put, we just aren't very good yet at preventing psychiatric illness.

We do our best primary prevention when the psychiatric disorder is the result of an identifiable physical cause. We can prevent cognitive impairment and lowered IQ by checking babies for hypothyroidism and children for lead poisoning. You can prevent HIV psychosis by preventing the spread of HIV and keeping the disease under control to delay or prevent dementia. General paresis, or dementia due to advanced untreated syphillis, is pretty much gone now due to the invention of penicillin.

Unfortunately, we still don't know how to prevent schizophrenia or bipolar disorder. We may be about to find a way to prevent clinical depression, at least in some patients. The Associated Press today summarized the findings of an article in this week's issue of JAMA regarding the prophylactic use of an antidepressant in post-stroke patients. One hundred twenty-seven stroke patients were divided into three groups: one treated with escitalopram, one given therapy and one group given a placebo. The escitalopram group was significantly less likely to develop clinical depression over the course of the year following stroke than either of the two control groups.

Now I'm waiting for a study to see if prophylactic antidepressants are useful in other at-risk groups, like heart attack patients, who are also prone to clinical depression in the months following the attack.

It's only one study, but it's a start.
And now : an intrusion from Dinah. I've decided I like putting my comments on the front of the post.

So here's the problem with preventative psychiatry in it's infancy. In the studies above, the issue is one of Risk. I don't know that I'd want to take a medication (with all the risks, side effects, possible adverse reactions, and the question of the unknown longterm or short term effects) for a condition that one is at Risk for. Invariably, some people will be exposed to medications who would never develop the targeted illness. It's a hard sell for me, unless the risk is 100 per cent.

I think we like to think maybe if an illness is caught early in it's course, then it won't get as bad, or at least the symptoms can be treated earlier. This is one rationale for on-going psychotherapy in people who want to be seen between episodes: that therapy may prevent future episodes, may give people tools to prevent relapse, and that the subtle signs of illness may be caught sooner before they become full blown episodes.

Thank you for letting me join in here.