Link found between schizophrenia and middle-ear disease

New research suggests middle-ear disease could increase people's vulnerability to developing schizophrenia.

The study, published in the September issue of the British Journal of Psychiatry shows a greater association between middle-ear disease and schizophrenia than was found in a similar study carried out in 1995.

This latest study also shows an increase in the odds of developing schizophrenia if a person experiences left-sided middle-ear disease compared to right-sided or bilateral middle-ear disease.

The theory that ear disease can cause insanity by irritating the brain dates back to the 1890s. The proximity of the ear to the brain was believed to be of particular importance, with a study published in 1927 reporting rates of ear disease in 66% of 200 certified insane people.

However, the hypothesis that an ear infection can cause irritation to the overlying brain has received little interest. Instead, attention has been paid to the role of hearing impairment in the development of paranoid disorders in the elderly.

In this study, researchers set out to establish the rate of middle-ear disease pre-dating the onset of schizophrenia. Eighty-four patients with schizophrenia living in West Lancashire were identified. Each patient was matched with four non-psychiatric controls who were of the same gender, age, and were born at a similar time of year. This was to limit the effects of seasonality, since an excess of winter births has been proposed as a possible factor in schizophrenia.

A history of ear disease for each patient was obtained from their general practice medical records. Additional information on symptoms was also collected for the 84 patients with schizophrenia (the case group).

The study found that the rate of middle-ear disease pre-dating the onset of schizophrenia was higher in the case group than in the control group. Auditory hallucinations were also found to be significantly associated with middle-ear disease pre-dating schizophrenia.

The researchers concluded that middle-ear disease may be another aetiological factor which increases a person's vulnerability to developing schizophrenia - an association that is worthy of further research.

Reference:

"Middle-ear disease and schizophrenia: case-control study."
Mason P, Rimmer M, Richman A, Garg G, Johnson J and Mottram P (2008)
British Journal of Psychiatry, 193:192-196 

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