Depression: Diagnosis and Differential Diagnosis

Diagnosis and Differential Diagnosis

The detection of depression in both primary care settings and mental health settings requires the presence of mood disturbance or loss of interest and pleasure in activities for 2 weeks or more accompanied by at least four other symptoms of depression. There are problems in differential diagnosis because depressive experiences vary from individual to individual. MDD is sometimes called unipolar depression or recurrent unipolar depression because the depressive episodes tend to recur in a lifetime. Dysthymic disorder (DD) is characterized by at least 2 years of depressed mood accompanied by two or three depressive symptoms which falls short of threshold criteria for a major depressive episode. Depressive disorder not otherwise specified (DDNOS) includes a set of conditions which do not meet criteria for MDD, DD, or adjustment disorder with depressed mood. These syndromes include premenstrual dysphoric disorder, minor depressive disorder, recurrent brief depressive disorder and postpsychotic depressive disorder occurring during the residual phase of schizophrenia. In DSM-IV, two other depressive disorders are diagnosed based upon etiology and include mood disorder due to a general medical condition and substance-induced mood disorder.

The core symptoms comprising a major depressive episode are illustrated in the DSM-IV criteria. Each symptom is critical to evaluate in a patient with depressive symptomatology since each represents one of the essential features of a major depressive episode. Their persistence for much of the day, nearly every day for at least 2 weeks, is the criterion for diagnosis. The clinical syndrome is associated with significant psychological distress or impairment in psychosocial or work functioning.

The clinical observation of mood reveals variations in presentation. An individual may have depressed symptomatology and experience typical sadness. Another individual may deny sadness and experience internal agitation and dysphoria. Another individual with depression may experience no feelings at all, and the depressed mood is inferred from the degree of psychological pain that is exhibited. Some individuals experience irritability, frustration, somatic preoccupation and the sensation of being numb.

An equally important aspect of the depressive experience involves loss of interest or pleasure, when an individual feels no sense of enjoyment in activities which were previously consid-ered pleasurable. There is associated reduction in all drives in-cluding energy and alteration in sleep, interest in food and inter-est in sexual activity.

A common experience of insomnia or hypersomnia is noted in individuals with persistent depression. Observations of psychomotor activity include profound psychomotor retardation leading to stupor in more severe cases or alternatively significant agitation leading to inability to sit still and profound pacing in agitated forms of depression.

The complaint of guilt or guilty preoccupation is a com-mon aspect of the depressive syndrome. Delusional forms of guilt are a common presentation of depressive disorder with psychotic features.

The loss of ability to concentrate, to focus attention and to make decisions is a particularly distressing symptom for indi-viduals. One may experience a loss of memory which simulates dementia. Loss of concentration is reflected in an inability to per-form both complicated and more simple tasks. The loss of ability to perform in school may be a symptom of MDD in children, and memory difficulties in the older adult may be mistaken for a primary dementia. In some older adults, a depressive episode with memory difficulties occurs in the early phase of an evolving dementia.

The most common psychiatric syndrome associated with thoughts of death, suicidal ideation, or completed suicide is MDD. The experience of hopelessness is commonly associated with suicidal ideation. The preoccupation with suicide in MDD requires that the assessment always includes careful monitoring of suicidality.

Subtyping of MDD

The current subtyping of MDD is based on severity, cross-sec-tional features and course features.