Mental Disorders Due to a General Medical Condition

Mental Disorders Due to a General Medical Condition

Introduction

This deals with disorders characterized by mental symp-toms which occur due to the direct physiological effect of a general medical condition. In evaluating patients with mental symptoms of any sort, one of the first questions to ask is whether those symp-toms are occurring as part of a primary psychiatric disorder or are caused by a general medical condition, and Figure 33.1 presents a decision tree designed to help in making this decision. The first step is to review the history, physical examination and laboratory tests to see if there is evidence for the presence of a general medi-cal disorder that could plausibly cause the mental symptoms in question. In making this determination, one looks not only for a temporal correlation (e.g., the onset of a psychosis shortly after starting or increasing the dose of a medication), but also keeps in mind well-documented associations between certain mental symptoms (e.g., depression) and certain general medical condi-tions (e.g., Cushing’s syndrome). If it appears, at this point, that the mental symptoms could indeed be occurring secondary to a gen-eral medical condition, the next step involves determining whether or not these symptoms could be better accounted for by a primary psychiatric disorder. For example, consider the case of a 45-year-old man with a history of recurrent major depression, currently euthymic, who begins a course of steroids for asthma and then, within a week, becomes depressed. The steroids are stopped but the depression continues. In this case, if the depression had cleared shortly after stopping the steroids, one might make the case that the depression occurred secondary to the steroid treatment; the persistence of the symptoms, however, argues strongly that this depression represents rather a recurrence of the major depression.

Once it appears that the mental symptoms in question could well directly result from a general medical condition and could not be better accounted for by a primary psychiatric disorder, then it re-mains to classify these symptoms into one of the specific types noted in Figure 33.1, and to proceed to the appropriate section below. There is also, at the end of the decision tree, a residual category for “unspeci-fied” mental symptoms, and two such syndromes, not uncommonly found in consult-liaison work, are included, namely pseudobulbar palsy and the Klüver–Bucy syndrome.

In caring for patients with mental disorders due to a general medical condition, the question arises as to whether or not symp-tomatic treatment for these mental symptoms should be offered. First, one must determine whether the mental symptoms demand emergent treatment. Consider, for example, a postictal psychosis characterized by delusions of persecution which prompt the patient to become assaultive: here, even though the condition itself will eventually resolve spontaneously, symptomatic treatment of the psychosis is required to protect the patient or others. In cases where the mental symptoms do not present an emergency, one looks to whether the underlying general medical condition is treatable or not. For example, in the case of psychosis due to Huntington’s dis-ease, as the underlying condition is not treatable, one generally proceeds directly to symptomatic treatment. In cases where the un-derlying condition is treatable, then one must make a judgment as to whether, with treatment of the underlying general medical con-dition, the mental symptoms will resolve at a clinically acceptable rate. Consider, for example, a patient with anxiety due to hyperthy-roidism who has just begun treatment with an antithyroid drug. In such a case, the decision as to whether to offer a benzodiazepine as symptomatic treatment for the anxiety depends not only on the se-verity and tolerability of the anxiety, but also on the expected time required for the antithyroid drug to resolve the hyperthyroidism: here, clearly, considerable clinical judgment is required.