Several studies suggest hearing impairment as a risk factor for psychosis. Hearing impairment is highly prevalent and potentially reversible, as it can be easily diagnosed and sometimes improved. Insight in the association between hearing impairment and psychosis can therefore contribute to prevention of psychosis. This paper provides meta-analyses of all epidemiologic evidence on the association between hearing impairment and psychosis and summarizes mechanisms that potentially underlie this relationship. Meta-analyses showed an increased risk of hearing impairment on all psychosis outcomes, such as hallucinations (OR 1.40(95%CI 1.18-1.65; n=227,005)), delusions (OR 1.55(95%CI 1.36-1.78; n=250,470)), psychotic symptoms (OR 2.23(95%CI 1.83-2.72; n=229,647) and delirium (OR 2.67(95%CI 2.05-3.48; n=12,432). Early exposure to hearing impairment elevated the risk of later development of schizophrenia (OR 3.15(95%CI 1.25-7.95; n=50,490)). Potential mechanisms underlying this association include loneliness, diminished theory of mind, disturbances of source monitoring and top-down processing and deafferentiation. Early assessment and treatment of hearing impairment in patients with (high risk of) psychosis may be essential in psychosis treatment and prevention.
Keywords: Delirium; Delusion; Hallucination; Hearing impairment; Hearing loss; Mechanisms; Meta-analysis; Psychosis; Psychosis prevention; Review; Risk factor; Schizophrenia.
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