| Previous studies have indicated that (1) The group of vital
(endogenous) depressions encompasses a subgroup with a central
serotonin (5-hydroxytryptamine; 5-HT) deficiency. (2) Abolition of
this deficiency--with the aid of 5-hydroxytryptophan (5-HTP), a 5-HT
precursor, or clomipramine, a 5-HT reuptake inhibitor--leads to
abatement of depressive symptoms. It therefore seems plausible that
the suspected 5-HT deficiency contributes to the development of
depressive symptoms instead of resulting from them. (3) In a majority
of patients, the suspected 5-HT deficiency persists even when the
depressive symptoms have disappeared and the medication has been
discontinued. This suggested that the disturbed central 5-HT
metabolism is not a direct causal, but a predisposing factor. If so,
abolition of the suspected 5-HT deficiency, e.g., with the aid of 5-
HTP, would be expected to have a prophylactic effect. As predicted, 5-
HTP was found in the present study to reduce the relapse rate in
recurrent vital depressions with both a unipolar and bipolar course.
The prophylactic effect was most pronounced in patients with
persistent disorders of central 5-HT metabolism; this observation,
however, requires corroboration. 5-HTP prophylaxis is the first aimed
(i.e., pathological substrate-oriented) type of chemoprophylaxis
known in psychiatry.
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