Verbal communication plays a vital role in human life and is one of the defining characteristics of our species. It not only helps to facilitate the sharing of information and knowledge, but also helps people to develop relationships with others. Any difficulty in this area can leave a lasting impact on a patient's life. Speech is a distinct, complex, and dynamic motor activity that helps us express our thoughts and emotions. Communication disorders, including problems related to language and voice, are pronounced in several mental illnesses.
Schizophrenia is a serious and highly disabling mental illness. A great deal of this disability is related to communication difficulties. Patients with schizophrenia have difficulty making themselves understood in part because of abnormalities in thought content (delusions and hallucinations) and process (loosening of associations). At a more elemental level, schizophrenia is associated with severe difficulties with pragmatics (the contextual and interpersonal aspects of language).1,2 More fundamental aspects of language in schizophrenia are less studied but seem to be preserved for the most part. Specifically, syntax (grammatical rules), morphology (changes in individual words to mark tense, number), and semantics (meaning of individual words) are generally unaffected, aside from id-iosyncratic use of common words and occasionally neologisms.3
At the most elemental level, schizophrenia may be associated with alterations in phonology (production of individual linguistic sounds), prosody, and voice quality.3 These changes may be subtle and interpreted as flat affect or an “odd voice” but may also be severe, rendering the patient nearly unintelligible. “Dysarthria” is a fairly broad term that can include the speech subsystems of respiration, phonation, resonance, prosody, and articulation. Dysarthria can lead to impairments in intelligibility, audibility, naturalness, and efficiency of vocal communication.4 Such vocal changes are commonly noted by psychiatrists who treat serious mental illness and have been discussed in the literature since the mid-19th century, well before the era of neuroleptic use.5–9 Surprisingly, this potentially disabling aspect of schizophrenia has received relatively little attention in the literature.10 The following cases are illustrative.
Illustrative Case 1
An 80-year-old woman with a lifelong history of paranoid schizophrenia has resided in a Veterans Affairs community living center (CLC) skilled nursing facility for the past 9 years. Her illness was characterized by irritability and copious persecutory delusions, mostly involving people trying to have her incarcerated or executed, sometimes with associated auditory hallucinations. She had never lived independently. On admission she had been treated with perphenazine but exhibited moderate pseudoparkinsonism; she was subsequently treated with clozapine, then thioridazine, then olanzapine, with partial improvement of the pseudoparkinsonism but no improvement of her psychotic symptoms and no appreciable change in her voice. She is generally difficult to understand; our subjective impression was that perhaps 20% to 30% of her speech is intelligible. Her speech is rushed, cluttered, poorly articulated, and with reduced self-monitoring (ie, diminished awareness of her poor articulation and poor intelligibility), varying markedly with her emotional state. None of these aspects of her speech were affected by any medication changes over the course of treatment. The poor self-monitoring is especially disabling, as she is generally aware when she is not understood and easily frustrated and angered by this, but is unaware of the need to modify her speech accordingly. Speech behaviors and intelligibility improved significantly with therapy directed at slowing her speaking rate and using pacing techniques, but carry-over outside of therapy sessions is almost nil.
Illustrative Case 2
A 73-year-old man with a lifelong history of undifferentiated schizophrenia and quadriplegia due to cervical spinal stenosis has resided in a CLC for 23 years. Since at least the time of admission, he has exhibited pressured, incoherent speech. His speech is almost completely unintelligible; perhaps about 10% of utterances are clear. He has clear loosening of associations as well as copious bizarre, often somatic delusions (such as having leprosy or a ruptured ectopic pregnancy, or his lungs being inside out). Over the years, his treatment has included haloperidol, perphenazine, olanzapine, and quetiapine; he stopped taking neuroleptics about 2.5 years ago. He has never manifested any pseudoparkinsonism or tardive dyskinesia, and his incoherent speech, delusions, and voice have all remained unchanged regardless of medications or after discontinuing all medications. His speech is hypernasal with severe articulatory insufficiency; the articulatory distortions appear to be related to reduced labial and lingual mobility and coordination. No aspects of his speech were affected by medication changes or discontinuation. He is unable to engage in any type of speech therapy.
Illustrative Case 3
A 75-year-old man with a lifelong history of paranoid schizophrenia has resided in a CLC for 7 years. He has prominent auditory command hallucinations and delusions of thought insertion and control. He had been treated over the years with perphenazine and later with olanzapine and then risperidone. The olanzapine had led to an approximately 50-kg weight gain, so his neuroleptic was switched from risperidone to ziprasidone on admission to the CLC and he ultimately lost about 30 kg. He has exhibited no pseudoparkinsonism or tardive dyskinesia. He is generally pleasant and conversant and is almost completely intelligible, but his speech is characterized by a nasal quality, fast pace, and decreased prosodic variation; pauses were placed inappropriately with respect to the flow of conversation. None of these characteristics were affected by medication changes.
To capture the true nature of vocal changes in schizophrenia, one would ideally examine younger or first-episode patients with minimal to no neuroleptic exposure and minimal medical comorbidity. The patients discussed here are not an ideally representative sample, as all were older, fairly ill, and required skilled nursing care. All three patients described here had an extensive history of neuroleptic use, although it is noteworthy that medication changes or discontinuation during their stay in the CLC had no appreciable qualitative or quantitative effect on voice quality. As expected, staff interactions with the patients in Illustrative Cases 1 and 2, who were difficult to understand, were limited; in fact, staff often questioned whether those patients' communication problems were indicative of dementia.
Vocal disturbances in patients with schizophrenia have been described for centuries and have historically been considered a core symptom of the illness. In the 19th century, Pinel, Esquirol and Seglas all commented on vocal changes in schizophrenia,9 and Kraepelin et al.5 discussed vocal changes in detail in 1919, including “similarity in sound” (“play[ing] senselessly with words and sounds”) and “derailments in linguistic expression” (wherein patients would “bellow, screech, murmur or whisper… [speaking] in falsetto, through their noses, in an artificial bass voice [that can] pass suddenly from one key to another”). In 1952, Moskowitz6 described the voice in people with schizophrenia as “monotonous, weak, unsustained [with a] flat vocal characteristic.” In 1954, Moses7 discussed a number of vocal characteristics of schizophrenia at length, including decreased nasal resonance (in contrast to the hypernasality noted in Illustrative Cases 2 and 3), rhythmic repetition of vocal patterns, melodic aspects having a jumping rather than gliding character uncorrelated to content, and placement of accent inappropriate to content.
Perhaps the most consistent finding about vocal changes in schizophrenia is that there are few consistent findings.8–10 Stein10 has noted that vocal changes tend to be stable in individual patients but vary widely between patients. The most replicated results in more modern and rigorous studies using quantitative speech analysis have been a decreased range of pitch and volume and an increase in speech pauses,3,8–13 and evidence that aprosody (“flat affect”) may correlate with decreased range of lingual movements;13,14 it is not clear that such changes could render a patient unintelligible, even if severe. Epstein-Lubow et al.15 have also published small study demonstrating abnormal voice onset time (VOT) (ie, the interval from release of an initial stop consonant [p, b, t, d, k or g] to onset of phonation) in five patients with schizophrenia. This is an interesting finding because VOT is involved in distinguishing between voiced and unvoiced stops (such as b vs p) and, therefore, in intelligibility. Our sample size was small, and, therefore, it is difficult to comment on any common features, but all of our patients exhibited rapid speech, some degree of increased nasality, and evidence of poor self-monitoring. They certainly exhibited more differences in voice than similarities.
The impact of neuroleptic medication on these vocal changes has been poorly explored and is far more challenging in an era when unmedicated patients with severe, chronic schizophrenia are almost nonexistent. Sinha et al.16 noted a correlation between both duration of and extrapyramidal effect propensity of neuroleptic use, and global measures of dysarthria. It is also likely that patients with antipsychotic-induced pseudoparkinsonism share vocal features with patients with idiopathic Parkinson's disease. Graux et al.17 also reported that total daily neuroleptic dose correlated with higher fundamental vocal pitch in a group of patients with schizophrenia, although patients were not stratified by specific neuroleptic agent. The authors believed that this higher pitch was related to laryngeal rigidity. However, the preponderance of evidence suggests that neuroleptic medication is generally only a small part of the picture; many reports of vocal changes in patients with schizophrenia antedate the introduction of these agents,5–7,9 and both Stein10 and Covington et al.14 found no correlation between vocal changes and neuroleptic use.
The mechanisms underlying the vocal changes in schizophrenia are entirely unclear. The oldest sources were merely descriptive;9 later sources from the mid-20th century describe dysarthria and vocal changes as one of a litany of “neurologic soft signs” (NSS) seen in schizophrenia and loosely attributed to mild central nervous system dysfunction.18,19 NSS have been postulated to be an intrinsic component of schizophrenia as they are seen in patients who are drug-naïve and experiencing their first episode.18–20 In a 2006 study, Varambally et al.19 reported dysarthria and kinetic abnormalities as the two most prominent NSS in a cohort of drug-naïve patients with schizophrenia; the authors viewed these abnormalities as evidence of cerebellar dysfunction.
The marked inter-individual variation in vocal characteristics of patients with schizophrenia, however, argues against any consistent locus of pathology. There is a considerable body of literature demonstrating elemental deficits in sound discrimination in schizophrenia,21,22 and it has been shown that these acoustic deficits correlate strongly with deficits in emotion recognition.23 It is conceivable, but not studied, that these acoustic deficits might also affect self-monitoring of voice, leading to various vocal abnormalities. A more intriguing possibility is that, for these or other reasons, people with schizophrenia may be less sensitive to comprehension cues from the listener. Cherry24 described speech in schizophrenia as reminiscent of that of a speaker on the telephone (ie, speaking without apparent benefit of social cues and feedback from the listener); this apparent lack of feedback was elaborated upon by Covington et al.3 Over a period of years or decades, this could conceivably lead to major deviation from normal, comprehensible speech, but probably not in the same direction in all people; this is a particularly compelling reason to study vocal changes in younger or even presymptomatic patients or, optimally, to study patients longitudinally over years to decades. Indeed, Spoerri8 speaks of speech in schizophrenia as ultimately no longer supporting communication and becoming incomprehensible. This may be analogous to the finding by Langdon et al.1 that defective pragmatics in speech of people with schizophrenia is related to theory of mind deficits, leading to an inability to modify discourse based on cues from the listener.
Speech and language interventions in schizophrenia have not been studied well, but existing recommendations suggest individually addressing and remediating problem areas using traditional approaches while keeping in mind the person's current emotional state. Therapy may require adjustments and flexibility regarding length of care, consistency of treatment sessions, introducing motivational components, co-treatment with other members of the multidisciplinary team, and responding to changes in mental health and in the environment.25 Most reports in this population involve therapy directed at pragmatics and speech content, not fundamental intelligibility. For example, Wong and Woolsey26 attempted to teach basic conversational skills to four patients with chronic schizophrenia. Skills acquisition was slow and there was little retention after discontinuation of treatment. This pattern was also observed in the patient in Illustrative Case 1, who did not improve significantly despite all the efforts at speech therapy. She was able to learn tactile cueing to slow down her speaking rate, but functional carryover after therapy sessions was nil. Overall, she did not seem to value the potential benefits of becoming more intelligible, and progress was limited by irritability and poor motivation.
People with schizophrenia may have significant speech and language impairments that affect their integration into society. Vocal changes in people with schizophrenia have been noted for almost two centuries but have received surprisingly little study despite their potentially disabling consequences. To date, few consistent vocal characteristics have been identified. There is little information about vocal changes early in the course of the illness and virtually no information about longitudinal course. The role of speech and language therapy with this population has been limited and has historically focused far more on pragmatics and social skills than on voice, and most reports of treatment thus far have been discouraging. We feel that this is a fruitful area of investigation that may ultimately yield substantial improvements in quality of life for many patients.
- Langdon R, Coltheart M, Ward PB, Catts SV. Disturbed communication in schizophrenia: the role of poor pragmatics and poor mind-reading. Psychol Med. 2002;32(7):1273–1284. https://doi.org/10.1017/S0033291702006396 PMID: doi:10.1017/S0033291702006396 [CrossRef]12420896
- Bambini V, Arcara G, Bechi M, Buonocore M, Cavallaro R, Bosia M. The communicative impairment as a core feature of schizophrenia: frequency of pragmatic deficit, cognitive substrates, and relation with quality of life. Compr Psychiatry. 2016;71:106–120. https://doi.org/10.1016/j.comppsych.2016.08.012 PMID: doi:10.1016/j.comppsych.2016.08.012 [CrossRef]27653782
- Covington MA, He C, Brown C, et al. Schizophrenia and the structure of language: the linguist's view. Schizophr Res.2005;77(1):85–98. https://doi.org/10.1016/j.schres.2005.01.016 PMID: doi:10.1016/j.schres.2005.01.016 [CrossRef]16005388
- Aronson AE. Clinical Voice Disorders: An Interdisciplinary Approach. New York, NY: Thieme; 1990:2–11.
- Kraepelin E, Barclay RM, Robertson GM. Dementia Praecox and Paraphrenia. Chicago, IL: Chicago Medical Book; 1919:65–66.
- Moskowitz EM. Voice quality in the schizophrenic reaction type. Speech Monogr. 1952;19:118–119.
- Moses PJ. The Voice of Neurosis. New York, NY: Grune & Stratton; 1954:122–124.
- Spoerri TH. Speaking voice of the schizophrenic patient. Arch Gen Psychiatry.1966;14(6):581–585. https://doi.org/10.1001/archpsyc.1966.01730120021003 PMID: doi:10.1001/archpsyc.1966.01730120021003 [CrossRef]5934868
- Chevrie-Muller C, Sevestre P, Seguier N. Speech and psychopathology. Lang Speech. 1985;28(Pt 1):57–79. https://doi.org/10.1177/002383098502800104 PMID: doi:10.1177/002383098502800104 [CrossRef]3897749
- Stein J. Vocal alterations in schizophrenic speech. J Nerv Ment Dis.1993;181(1):59–62. https://doi.org/10.1097/00005053-199301000-00012 PMID: doi:10.1097/00005053-199301000-00012 [CrossRef]8419517
- Chevrie-Muller C, Seguier N, Spira A, Dordain M. Recognition of psychiatric disorders from voice quality. Lang Speech. 1978;21(1):87–111. https://doi.org/10.1177/002383097802100106 PMID: doi:10.1177/002383097802100106 [CrossRef]692245
- Bedwell JS, Cohen AS, Trachik BJ, Deptula AE, Mitchell JC. Speech prosody abnormalities and specific dimensional schizotypy features: are relationships limited to male participants?J Nerv Ment Dis. 2014;202(10):745–751. https://doi.org/10.1097/NMD.0000000000000184 PMID: doi:10.1097/NMD.0000000000000184 [CrossRef]25198702
- Compton MT, Lunden A, Cleary SD, et al. The aprosody of schizophrenia: computationally derived acoustic phonetic underpinnings of monotone speech. Schizophr Res. 2018;197:392–399. https://doi.org/10.1016/j.schres.2018.01.007 PMID: doi:10.1016/j.schres.2018.01.007 [CrossRef]29449060
- Covington MA, Lunden SLA, Cristofaro SL, et al. Phonetic measures of reduced tongue movement correlate with negative symptom severity in hospitalized patients with first-episode schizophrenia-spectrum disorders. Schizophr Res. 2012;142(1–3):93–95. https://doi.org/10.1016/j.schres.2012.10.005 PMID: doi:10.1016/j.schres.2012.10.005 [CrossRef]23102940
- Epstein-Lubow G, Hochstadt J, Lieberman P, Kaplan GB. Speech production in schizophrenia: preliminary data regarding voice onset time. Schizophr Res. 2006;82(2–3):267–269. https://doi.org/10.1016/j.schres.2005.11.005 PMID: doi:10.1016/j.schres.2005.11.005 [CrossRef]
- Sinha P, Vandana VP, Lewis NV, Jayaram M, Enderby P. Predictors of effect of atypical antipsychotics on speech. Indian J Psychol Med.2015;37(4):429–433. https://doi.org/10.4103/0253-7176.168586 PMID: doi:10.4103/0253-7176.168586 [CrossRef]26702176
- Graux J, Courtine JB, Bruneau N, Camus V, El-Hage W. Higher fundamental voice frequency is related to extrapyramidal symptoms in schizophrenia. Schizophr Res. 2015;161(2–3):517–518. https://doi.org/10.1016/j.schres.2014.10.045 PMID: doi:10.1016/j.schres.2014.10.045 [CrossRef]
- Boks MP, Liddle PF, Burgerhof JG, Knegtering R, van den Bosch RJ. Neurological soft signs discriminating mood disorders from first episode schizophrenia. Acta Psychiatr Scand. 2004;110(1):29–35. https://doi.org/10.1111/j.1600-0447.2004.00298.x PMID: doi:10.1111/j.1600-0447.2004.00298.x [CrossRef]15180777
- Varambally S, Venkatasubramanian G, Thirthalli J, Janakiramaiah N, Gangadhar BN. Cerebellar and other neurological soft signs in antipsychotic-naïve schizophrenia. Acta Psychiatr Scand. 2006;114(5):352–356. https://doi.org/10.1111/j.1600-0447.2006.00837.x PMID: doi:10.1111/j.1600-0447.2006.00837.x [CrossRef]17022795
- Venkatasubramanian G, Latha V, Gangadhar BN, et al. Neurological soft signs in never-treated schizophrenia. Acta Psychiatr Scand. 2003;108(2):144–146. https://doi.org/10.1034/j.1600-0447.2003.00113.x PMID: doi:10.1034/j.1600-0447.2003.00113.x [CrossRef]12823171
- McLachlan NM, Phillips DS, Rossell SL, Wilson SJ. Auditory processing and hallucinations in schizophrenia. Schizophr Res. 2013;150(2–3):380–385. https://doi.org/10.1016/j.schres.2013.08.039 PMID: doi:10.1016/j.schres.2013.08.039 [CrossRef]24054462
- Donde C, Mondino M, Leitman DI, et al. Are basic auditory processes involved in source-monitoring deficits in patients with schizophrenia?Schizophr Res. 2019; S0920-9964:30211–7. https://doi.org/10.1016/j.schres.2019.05.034
- Leitman DI, Laukka P, Juslin PN, Saccente E, Butler P, Javitt DC. Getting the cue: sensory contributions to auditory emotion recognition impairments in schizophrenia. Schizophr Bull. 2010;36(3):545–556. https://doi.org/10.1093/schbul/sbn115 PMID: doi:10.1093/schbul/sbn115 [CrossRef]
- Cherry C. Speech disorders and mental disorders. In: de Reuck AVS, O'Connor M, eds. Disorders of Language. London, UK: J&A Churchill; 1964:285–298.
- Taylor-Goh S, ed. Royal College of Speech and Language Therapists Clinical Guidelines. Bicester, UK: Speechmark Publishing; 2005:83–91.
- Wong SE, Woolsey JE. Re-establishing conversational skills in overtly psychotic, chronic schizophrenic patients. Discrete trials training on the psychiatric ward. Behav Modif. 1989;13(4):415–431. https://doi.org/10.1177/01454455890134002 PMID: doi:10.1177/01454455890134002 [CrossRef]2818460