Changes in midbrain serotonin transporter availability in atypically depressed subjects after one year of psychotherapy.

Background: Psychotherapy is an effective treatment method for depression, but no differences in the psychotherapy response have been found between the subtypes of depression. The effect of psychotherapy on neurotransmitter transporter functions has never been recorded in depressed subjects.

Methods: Depressive outpatients (N=19) received psychodynamic psychotherapy for 12 months. All subjects fulfilled the DSM-IV criteria for depression, and 8 were classified as having atypical depression. The severity of depression was assessed with the 29-item Hamilton Depression Rating Scale (HAM-D-29). Midbrain serotonin transporter (SERT) and striatum dopamine transporter (DAT) densities were recorded using single photon emission computed tomography (SPECT) brain imaging with the [123I]nor-beta-CIT radioligand before and after psychotherapy.

Results: Midbrain SERT density significantly increased during psychotherapy in atypicals but not in nonatypicals. There were no changes in the levels of DAT.

Conclusions: The psychotherapy-related SERT elevation of atypically depressed subjects may be due to some unknown adaptive mechanisms inducing an increase in either the levels of SERT or serotonergic nerve terminals and therefore enhancing serotonergic activity and improving mood.