Despite the clinical use of antidepressants during half a century, there is no uniform theory regarding their mechanism of action, the factors influencing their clinical efficacy and some of their side-effects.
In addition to the previously prevalent monoamine theory, more data have been accumulated concerning the effects of antidepressants on neuroplasticity during the last decade.
A serious and frequent problem is the lack of a clinical effect or an unsatisfactory clinical effect. The clinical effect of antidepressants is inf luenced by several factors, e.g. patient’s compliance with treatment, the antidepressant used, inadequate dose and/ or duration of treatment, genetic factors, patient gender and dosage form.
It has also not been definitely confirmed whether the antidepressants cause some of the possible side-effects that have been attributed to them – e.g. harmful effect during pregnancy and an increase in suicidal behaviour.