Affective Prosody and Depression After Stroke

Neuropsychiatric disorders occur frequently after stroke and have a detrimental impact on functional outcomes and quality of life. Poststroke depression (PSD) is considered the most frequent clinical expression of these disorders and is often diagnosed at least 3 months after stroke. The identification of patients at risk for developing this disorder remains an important issue for clinicians because its early diagnosis is essential to improve therapeutic strategies. Although the need to identify new biomarkers associated with PSD is increasingly recognized, progress has been slow, despite considerable investment. The diagnosis of PSD is often complex because of the strong overlap between somatic symptoms related to stroke and those reported by patients during a depressive state. It is, therefore, essential that symptoms specific to PSD be identified. Impairment of affective prosody, defined as extraverbal information indicating the emotional state of the speaker, independent of verbal content, has been extensively reported in major depression. Prosody is defined as the set of objective parameters: the fundamental frequency of the voice signal (F 0 ), the intensity of the sound emission, the shimmer (small variations in glottal pulse amplitude), voice breaks, and the speech rate. Prosody is mediated by the right hemisphere, which is known to influence emotional communication. Although several studies have demonstrated that depressed patients speak louder and at a slower rate than healthy controls, the findings regarding prosody have been less consistent with some studies observing reductions in F 0 range, averages, or variability, as well as alterations of shimmer. The aim of this pilot study is, therefore, to evaluate the role of affective prosody in the first days after stroke in the prediction of PSD measured 3 months (M3) later. Because changes in emotional states are often coupled with modifications in laryngeal tension and subglottal pressure, it is hypothesized that affective prosody would be a reliable biomarker of this disorder.