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.