Masked depression under the light of the new biological and nosological research.

Recent biological research in psychiatry has shown strong relationships between disorders apparently very different but sharing some common symptoms (target symptom perspective) or psychopathology (functional psychopathology perspective). The serotonin involvement in a wide range of conditions (such as depressions and other mood disorders, anxiety disorders, suicidal and aggressive behaviours, impulsive control disorders) has been explained through the common link of serotonin deficiency in disorders and behaviours characterized by a poor control of impulses (multi-impulsive disorders). Psychotropic drugs, mainly antidepressants, enhancing the serotonin metabolism have demonstrated a positive therapeutical effect on those conditions. But, the recent description of the so-called Recurrent Brief Depressive Episodes raises the question if those serotonin related conditions could be diagnosed as mood disorders. In fact, during the 70's in a pre DSM III era, all of these disorders had been considered as forms of masked depressions. This perspective raises also the question about what should be considered as primary in the disorders described, the underlying disturbance of impulsivity or the underlying mood disorder.