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Depression — theme
and variations
(This article was first printed in the October
2004 issue of the Harvard Mental Health
Letter. For more information or to order,
please go to http://www.health.harvard.edu/mental.)
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:
- sadness, hopelessness, loss of pleasure and
interest in life
- slow movements, lethargy, loss of energy,
sexual interest, and initiative
- anxiety
- restlessness, agitation, irritability, guilt,
and suicidal tendencies
- excessive sleep and appetite
The second, third, and fourth dimensions were
more highly correlated among siblings than among
unrelated persons. For example, if one sibling
had mainly the low-energy symptoms, the other
sibling was far more likely than average to have
those symptoms as well. The authors suggest that
these dimensions may help to identify genetically
distinct types of depression.
Korszun A, et al. “Familiality
of Symptom Dimensions in Depression,” Archives
of General Psychiatry (May 2004): Vol. 61,
No. 5, pp. 468–74.
Oquendo MA, et al. “Instability
of Symptoms in Recurrent Major Depression: A
Prospective Study,” American Journal
of Psychiatry (Feb. 2004): Vol. 161, No.
2, pp. 255–61.
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