This is more prominently the case for Huntington’s disease, in which depression is con- sidered to be the first neuropsychiatric symptom. There is some observational evidence that depression is less common as the dementia of Huntington’s disease progresses.
The risk of acute onset of a major depressive disorder following a CVA (within 1 day to a week of the event) appears to be strongly correlated with lesion location, with greatest risk associated with left frontal strokes and least risk apparently associated with right frontal lesions in those individuals who present within days of the stroke. The association with frontal regions and laterality is not observed in depressive states that occur in the 2—6 months following stroke.
Gender differences pertain to those associated with the medical condition (e.g., systemic lupus erythematosus is more common in females; stroke is somewhat more common in middle-age males compared with females).
Diagnostic markers pertain to those associated with the medical condition (e.g., steroid levels in blood or urine to help corroborate the diagnosis of Cushing’s disease, which can be associated with manic or depressive syndromes).
There are no epidemiological studies that provide evidence to differentiate the risk of sui- cide from a major depressive episode due to another medical condition compared with the risk from a major depressive episode in general. There are case reports of suicides in association with major depressive episodes associated with another medical condition.
There is a clear association between serious medical illnesses and suicide, particularly shortly after onset or diagnosis of the illness. Thus, it would be prudent to assume that the risk of suicide for major depressive episodes associated with medical conditions is not less than that for other forms of major depressive episode, and might even be greater.
Functional Consequences of Depressive Disorder
Due to Another Medical Condition
Functional consequences pertain to those associated with the medical condition. In gen- eral, it is believed, but not established, that a major depressive episode induced by Cush- ing’s disease will not recur if the Cushing’s disease is cured or arrested. However, it is also suggested, but not established, that mood syndromes, including depressive and manic/ hypomanic ones, may be episodic (i.e., recurring) in some individuals with static brain in- juries and other central nervous system diseases.
Depressive disorders not due to another medical condition. Determination of whether a medical condition accompanying a depressive disorder is causing the disorder depends on a) the absence of an episode(s) of depressive episodes prior to the onset of the medical condition, b) the probability that the associated medical condition has a potential to pro- mote or cause a depressive disorder, and c) a course of the depressive symptoms shortly after the onset or worsening of the medical condition, especially if the depressive symp- toms remit near the time that the medical disorder is effectively treated or remits.
Medication-induced depressive disorder. An important caveat is that some medical con- ditions are treated with medications (e.g., steroids or alpha-interferon) that can induce depres- sive or manic symptoms. In these cases, clinical judgment, based on all the evidence in hand, is the best way to try to separate the most likely and/ or the most important of two etiological fac- tors (i.e., association with the medical condition vs. a substance-induced syndrome).
Adjustment disorders. It is important to differentiate a depressive episode from an ad- justment disorder, as the onset of the medical condition is in itself a life stressor that could bring on either an adjustment disorder or an episode of major depression. The major dif- ferentiating elements are the pervasiveness the depressive picture and the number and quality of the depressive symptoms that the patient reports or demonstrates on the mental status examination. The differential diagnosis of the associated medical conditions is rel- evant but largely beyond the scope of the present manual.