Action (verb) fluency in schizophrenia: getting a grip on odd speech.
BACKGROUND
Formal thought disorder (TD) is a key symptom of schizophrenia with a significant impact on interpersonal relationships. Current cognitive models emphasize disordered language functioning and abnormalities accessing semantic representations. The cortical mechanisms for language and motor function are closely linked, hence action-related language may be impaired in TD, yet existing studies have focussed exclusively on object (noun) rather than action (verb) semantics.


METHODS
In order to examine this issue both action (verb) and traditional semantic (tools, fruits, musical instruments) and phonological (FAS) fluency tasks were completed by individuals with schizophrenia (N=53) and healthy controls (N=69). Fluency performance was measured as the total number of correct words generated in 60s. The Schizotypal Personality Questionnaire (SPQ) was used to index odd and disorganized speech, as well as positive and negative symptoms.


RESULTS
Fluency on all tasks was impaired in schizophrenia, compared to controls, with a similar effect size. Within the schizophrenia group Odd Speech was correlated with poor fluency for actions, tools and musical instruments but not fruit or phonological fluency. These action-related fluency deficits were also correlated with Constricted Affect and Social Anxiety but not with Unusual Perceptions/Odd Beliefs.


CONCLUSIONS
These results point to a unique connection and possible common aetiology between action fluency and odd speech in schizophrenia rather than a general impairment in language/executive functions common to fluency tasks. The findings provide the first evidence of a specific role of action-based language production deficits in TD together with a joint effect on social interaction skills.
School of Psychiatry and Clinical Neurosciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Perth, Australia. johanna.badcock@uwa.edu.au
Johanna C
JC
Badcock
Milan
M
Dragović
Coleman
C
Garrett
Assen
A
Jablensky
D000293:Adolescent; D000328:Adult; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D007802:Language; D007806:Language Disorders / Q000175:diagnosis / Q000209:etiology*; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010552:Personality Assessment; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000150:complications*; D013060:Speech; D013223:Statistics as Topic; D011795:Surveys and Questionnaires; D014705:Verbal Behavior / Q000502:physiology*; D055815:Young Adult