Abnormal speech articulation, psychomotor retardation, and subcortical dysfunction in major depression

Abstract

Psychomotor retardation, characterized by changes in speech, motility and cognition, is common in major depression. It is also a cardinal feature of subcortical disorders such as Parkinson's disease (PD). Based on this observation and other data it has been hypothesized that the retardation of depression is related to mesolimbic-nigrostriatal dysfunction. To further test this hypothesis, speech articulation in major depression was compared to that in PD, where disordered articulation is related to bradykinesia and rigidity caused by striatal dopamine depletion. Thirty subjects with major depression were compared with 30 patients with PD and 31 normal controls on 3 acoustic measures of articulation. Major depression and PD groups had significantly shortened voice onset time and decreased second formant transition compared to controls, and major depression also had increased spirantization. There were no differences between the depression and PD groups on any of the acoustic measures. These findings provide indirect support for the hypothesis that nigrostriatal dysfunction is related to psychomotor slowing in major depression.