The behavioural toxicity of the selective serotonin reuptake inhibitors

The serotonin reuptake inhibitors (SSRIs) are generally better tolerated than the traditional tricyclic antidepressants (TCAs) in the treatment of major depression. In particular the SSRIs are relatively free from cognitive and psychomotor effects likely to cause behavioural toxicity. Behavioural toxicity is studied using a battery of psychometric assessments. This paper discusses the effects of the TCAs and SSRIs on two such assessments, choice reaction time (CRT) and critical flicker fusion threshold (CFFT). CRT measures psychomotor speed, and CFFT assesses the information processing capacity of the CNS. The behavioural toxicity associated with the traditional TCAs can lead to an increased accident risk, whereas the SSRIs are not associated with such effects. Clinically relevant differences in the behavioural toxicity of the SSRIs are highlighted.