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Bradyphrenia and Bradykinesia Both Contribute to Altered Speech in Schizophrenia: A Quantitative Acoustic Study

Cannizzaro, Michael S PhD*†¶; Cohen, Henri PhD†‡; Rappard, Fred MD§; Snyder, Peter J PhD*‡∥

Cognitive and Behavioral Neurology: December 2005 - Volume 18 - Issue 4 - p 206-210
doi: 10.1097/01.wnn.0000185278.21352.e5
Experimental Study

Objective: To evaluate the relative contributions of motor and cognitive symptoms on speech output in persons with schizophrenia (SZ).

Background: Studies of speech production in SZ suggest that atypical prosody (eg, pause) is related to clinical symptoms manifest in flat affect and alogia. Others have suggested that a more general motor slowing, bradykinesia, leads to measurable speech changes.

Method: Thirteen participants with SZ and age-matched control subjects were included for between-group and by-task comparisons. Two levels of task complexity were analyzed acoustically to determine distinct and overlapping features of speech pause.

Results: For the free-speech task, group differences were found on measures of average pause duration, pause variability, percent pause, and cumulative pause time. Conversely, for the rote-speech task, group differences were found only on measures of average pause duration and pause variability.

Conclusions: In persons with SZ, differences in the average and variability of pause duration may be reflected in speech motor slowing, whereas more global measures (eg, percentage pause) may better reflect a paucity of thought and idea generation related to the cognitive-linguistic aspects of free speech. These findings corroborate and extend the paucity of thought hypothesis in SZ to include an influence of motor slowing on speech production.

From the *Voice Acoustics Laboratory, Pfizer Global Research & Development, Groton, Connecticut; †NeuroSolutions, Inc., Montréal, Québec, Canada; ‡Cognitive Neuroscience Center and Department of Psychology, Université du Québec à Montréal, Montréal, Québec, Canada; §CNS Early Clinical Development, Pfizer Global Research & Development, Ann Arbor, Michigan; ∥Department of Psychology, University of Connecticut, Storrs, Connecticut; and ¶Department of Communication Sciences, University of Vermont, Burlington, Vermont.

Received for publication November 26, 2004; revised April 26, 2005; accepted June 27, 2005.

This study was funded in total by Pfizer, Inc., and all authors have served as either employees or consultants to Pfizer Global Research & Development.

Reprints: Peter J. Snyder, Department of Psychology, University of Connecticut, 406 Babbidge Rd., Unit 1020, Storrs, CT 06269-1020 (e-mail: peter.j.snyder@gmail.com).

© 2005 Lippincott Williams & Wilkins, Inc.