The mental health residential care study: Predicting costs from resident characteristics

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Abstract
BACKGROUND Animal experimental studies suggest that the amino acid valine may decrease brain serotonin (5-HT) function by inhibiting the transport of the 5-HT precursor, L-tryptophan, across the blood barrier. The aim of the present study was to assess whether valine could decrease brain 5-HT function in healthy subjects and provoke symptomatic relapse in recently remitted depressed patients taking antidepressant drug treatment. METHOD We studied the effect of valine (30 g) on the prolactin (PRL) response to the 5-HT releasing agent, D-fenfluramine, in healthy male subjects and on the mood of 12 remitted depressed patients taking either selective serotonin re-uptake inhibitors (n = 10) or lithium and amitriptyline (n = 2). RESULTS Valine significantly lowered the PRL response to D-fenfluramine in healthy subjects. In the remitted depressives, valine caused a mild but detectable lowering of mood on a number of measures but only one patient experienced a significant relapse in mood. CONCLUSIONS Valine administration may decrease brain 5-HT neurotransmission in humans. This effect could explain the mild increase in depressive symptoms in patients taking 5-HT-potentiating drugs.