The effects of selective serotonin reuptake inhibitors (SSRIs) on speech diadochokinesis

By F.L.  Lu, K. Gopal, D. Farrow, H.L. Gooding


Patients with major depressive disorders have been shown to have parkinsonian-like speech, suggestive of nigrostriatal dysfunction and involvement of dopaminergic system causing psychomotor slowing and speech incoordination.  Selective serotonin reuptake inhibitors (SSRIs), effective drugs used to treat major depression, reportedly cause side effects including speech dysfunction- speech blockage, stuttering, and tremor.  Attempts to study adverse effects of antidepressants on speech have been few and often with mixed results.  Currently, the effect of SSRIs on speech remains uncertain and requires further study.  This study was to investigate association between speech diadochokinesis and depression with and without SSRIs.  Subjects consisted of 15 medically diagnosed depressive individuals and 13 normal controls.  Nine depressive subjects (MED) were on SSRIs (Prozac, Zoloft, Paxil, Celexa), whereas six depressive subjects (NMED) were not on any antidepressants.  Subjects produced rapid syllable repetitions of [puh], [tuh], [kuh], [huh] in two trials.  Speech data were analyzed acoustically for: (1) diadochokinetic rate, duration, and stability, (2) speaking and pause time, and (3) tremor.  The study shows: (1) NMED group had normal speech diadochokinesis, and (2) MED group demonstrated significantly slower and variable diadochokinetic rates.  Severity of disorder, effortfulness of motor and cognitive processing, psychomotor retardation, and psychophysiology will be discussed.