Harvard Mental Health Letter

Depression - theme and variations

In brief

Depression "" theme and variations

The American Psychiatric Association requires any five of nine symptoms for a diagnosis of major depression. As the definition implies, these symptoms do not all appear in everyone who is depressed. Two studies explore the consequences for the understanding of depression and come to contrasting conclusions. One study suggests that an individual patient's symptoms are not consistent, but change more or less unpredictably from one episode of depression to the next. The other study suggests that there are several sets of depressive symptoms that are distinguishable genetically and therefore likely to persist in a given individual.

American researchers studying 78 hospitalized patients who had had at least 2 episodes of severe depression found that, with a few exceptions, it was impossible to predict reliably from the symptoms of one episode which symptoms would appear in the next episode. The researchers also looked for the persistence of sets of symptoms that are regarded as characteristic of specific types of depression: atypical depression (excessive sleep and eating and weight gain, feelings of worthlessness); melancholic depression (insomnia, anxiety, appetite loss, slowed movements, feeling worse in the morning); and psychotic depression (paranoia, guilt, hypochondria, hopelessness). Again, there was no consistency; for example, a patient who had psychotic symptoms in the first episode and one who had melancholic symptoms in the first episode were equally likely to show psychotic (or melancholic) symptoms in the second episode. Among these patients, there were apparently no distinct types of depression. Instead, the same underlying illness was taking different forms at different times.

European researchers found evidence to the contrary in a large international genetic study including more than 1,000 biologically related siblings with recurrent depression. From answers to standard clinical interviews, they identified five groups of symptoms that often went together, which they call "dimensions" of depression:

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