MedWire News: The prevalence of auditory, visual, and cenesthetic hallucinations in patients with schizophrenia is significantly influenced by cultural as well as clinical factors, study results show.
The findings suggest that culture "should be taken into account to a greater extent in considerations concerning the pathogenesis of psychotic symptoms," say the researchers.
Susanne Bauer (Medical University of Vienna, Austria) and team studied the prevalence of different types of hallucinations among 1080 schizophrenia patients, aged 18-62 years, from seven countries (Austria [n=350], Lithuania [n= 73], Poland [n= 80], Georgia [n= 74], Ghana [n= 76], Nigeria [n= 324], and Pakistan [n= 103) on three continents.
All of the participants were assessed for psychotic symptoms over a 1-year period using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Axis I Disorders. A second instrument for the assessment of psychotic symptoms, the Fragebogen zur Erfassung psychotischer Symptome, was also used, as this was developed for cross-cultural comparison studies on psychotic symptoms in schizophrenia.
Overall, auditory hallucinations had the highest 1-year prevalence (74.8%), followed by visual hallucinations (39.1%), cenesthetic hallucinations (28.9%), and tactile, olfactory, and gustatory hallucinations (1.3%-6.6%).
The researchers found that the prevalence of various types of hallucinations differed significantly by country.
Indeed, African patients in Ghana and Nigeria had the highest prevalence of auditory hallucinations, at 90.8% and 85.4%, respectively, while European patients in Austria had the lowest, at 66.9%. In contrast, patients in Austria had the highest prevalence of cenesthetic hallucinations, at 36.3%, while those in Ghana and Nigeria had the lowest, at 18.7% and 18.8%, respectively.
Patients in Ghana and Nigeria also had the highest prevalence of visual hallucinations, at 50.8% and 53.9%, respectively, while Asian patients in Pakistan had the lowest, at just 3.9%.
There were no significant differences among countries regarding the prevalence of tactile, olfactory, and gustatory hallucinations.
The researchers also found that visual hallucinations were more common in younger than older patients, while cenesthetic hallucinations were more common in patients with a longer compared with a shorter duration of illness.
Bauer and team conclude in the journal Comprehensive Psychiatry: "In this study we were able to show that culture has a decisive impact on the prevalence of the kinds of hallucinatory experiences. However, there are also other factors like age, age at onset, and duration of illness that influence the rates of hallucinations."
They add: "Further studies in other societies are necessary to establish a consistent theory concerning the impact of culture on the frequency and shape of hallucinations in schizophrenia."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
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