Tryptophan, affective disorder and stress. An hypothesis.

Patients suffering from unipolar illness and anticipating a complex investigation, or the first of a series of ECTs, had lower total tryptophan levels than control subjects under the former circumstances. This suggested a qualitative or quantitative difference in response to stress, associated with a fall in the amino acid level. It was hypothesized that this might selectively decrease synthesis of both protein and 5-HT in serotoninergic neurones.