What do we really know about blunted vocal affect and alogia? A meta-analysis of objective assessments

Abstract

Deficits in nonverbal vocal expression (e.g., blunted vocal affect, alogia) are a hallmark of schizophrenia and are a focus of the Research Domain Criteria initiative from the National Institute of Mental Health. Results from studies using symptom rating scales suggest these deficits are profound; on the order of four to six standard deviations. To complement this endeavor, we conducted a meta-analysis of studies employing objective analysis of natural speech in patients with schizophrenia and nonpsychiatric controls. Thirteen studies, collectively including 480 patients with schizophrenia and 326 nonpsychiatric controls, were identified. There was considerable variability across studies in which aspects of vocal communication were examined and in the magnitudes of deficit. Overall, speech production (reflecting alogia) was impaired at a large effects size level (d = −.80; k = 13), whereas speech variability (reflecting blunted affect) was much more modest (d = −.36; k = 2). Regarding the former, this was largely driven by measures of pause behavior, as opposed to other aspects of speech (e.g., number of words/utterances). On the other hand, ratings of negative symptoms across these studies suggested profound group differences (d = 3.54; k = 4). These data suggest that only certain aspects of vocal expression are affected in schizophrenia, and highlight major discrepancies between symptom rating and objective-based measures. The discussion centers on advancing objective analysis for understanding vocal expression in schizophrenia and for identifying and defining more homogenous patient subsets for study.

Reward-dependent modulation of working memory is associated with negative symptoms in schizophrenia

“…Considering that patients with schizophrenia have lower cognitive abilities compared to healthy controls, the effects are magnified, since fewer resources are available in the first place. Our data suggest that patients with more pronounced diminished expression do not only have less cognitive resources available as proposed by Cohen et al (2012Cohen et al ( , 2013Cohen et al ( , 2014aCohen et al ( , 2014b, but that they have a specific problem in adjusting resources according to their priority. In other words, potential reward fails to recruit additional cognitive resources, which in turn leads to diminished expressive behavior.…”

“…This idea is in line with the cognitive resource limitation model (Cohen et al, 2012(Cohen et al, , 2013(Cohen et al, , 2014a(Cohen et al, , 2014b. Cohen proposes that effective expression requires a range of mental resources.…”

Speech deficits in serious mental illness: A cognitive resource issue?

“…During each frame, frequency and volume are quantified, and information about pauses, utterances, intonation and emphasis are extracted. Our selection of these variables was based on a recent psychometric analysis of 1350 young adults using this procedure (Cohen et al, 2014b). We examined the following variables in this study: pause number – total count of all pauses (>150 ms) in the speech sample, pause length – average length of pauses (in milliseconds), utterance length – average length of utterances (in milliseconds), intonation – average standard deviation of fundamental frequency values computed separately for each utterance, intensity – average intensity values (i.e., volume) computed within each utterance, emphasis – average standard deviation of intensity values, computed separately for each utterance.…”

“…Furthermore, prior studies have employed limited indices of speech production (e.g., word counts) and variability (e.g., mean volume, variability of F0). This is a critical point highlighted in a recent meta-analysis of objective measures of speech deficits in schizophrenia (Cohen et al, 2014b) – that there has been little consistency in which speech variables are reported across studies (e.g., eight different variables of speech production reported across 13 studies), and considerable disparity in magnitude of deficit across these variables (range of d ’s = −.20 – −2.56). In the present study, we addressed these limitations and conducted the most sophisticated study to date clarifying the cognitive underpinnings of speech deficits in SMI.…”

Vocal expression in schizophrenia: Less than meets the ear.

“…A recent meta-analysis (Cohen, Mitchell, et al, 2014) highlights potential limitations with clinical ratings scales and our poor understanding of vocal abnormalities in schizophrenia more generally. With respect to vocal expression ratings from the Scale for the Assessment of Negative Symptoms (e.g., blunted vocal affect; Andreasen, 1989), patients with schizophrenia versus nonpatient controls showed profound deficits on the order of three to five standard deviations (i.e., Cohen’s d = 3.42 – 4.39).…”