The research literature shows that psychotherapy is effective compared
with no treatment and placebo treatment. The effects of therapy seem
to be relatively lasting. They are achieved in a relatively short time
, and the percentage of patients who show substantial improvement incr
eases as the number of psychotherapy sessions increases. There is litt
le evidence of specific efficacy for particular techniques. PI small p
roportion of patients (5%) seem to deteriorate during, and perhaps bec
ause of, psychotherapy interventions.