a1 Division of Public Health Epidemiology, Department of Public Health Sciences, Karolinska Institutet Norrbacka, Stockholm, Sweden
a2 Centre for Women's Mental Health, Manchester Academic Health Sciences Centre, University of Manchester, UK
a3 Centre for Epidemiology and Community Medicine, Stockholm County Council, Sweden
Background Schizophrenia often becomes manifest in late adolescence and young adulthood but deviations in physical and behavioural development may already be present in childhood. We investigated the relationship between hearing impairment (measured with audiometry) and speech impairment (broadly defined) at age 4 years and adult risk of non-affective psychosis.
Method We performed a population-based, case–control study in Sweden with 105 cases of schizophrenia or other non-affective psychoses and 213 controls matched for sex, date and place of birth. Information on hearing and speech impairment at age 4, along with potential confounding factors, was retrieved from Well Baby Clinic (WBC) records.
Results Hearing impairment [odds ratio (OR) 6.0, 95% confidence interval (CI) 1.6–23.2] and speech impairment (OR 2.6, 95% CI 1.4–4.9) at age 4 were associated with an increased risk of non-affective psychotic illness. These associations were mutually independent and not explained by parental psychiatric history, occupational class or obstetric complications.
Conclusions These results support the hypothesis that psychosis has a developmental aspect with presentation of antecedent markers early in childhood, long before the disease becomes manifest. Our findings add to the growing evidence that early hearing impairment and speech impairment are risk indicators for later non-affective psychosis and possibly represent aetiological clues and potentially modifiable risk factors. Notably, speech impairment and language impairment are both detectable with inexpensive, easily accessible screening.
(Received October 06 2011)
(Revised October 04 2012)
(Accepted October 19 2012)
(Online publication November 30 2012)
c1 Address for correspondence: Dr A. Fors, Division of Public Health Epidemiology, Department of Public Health Sciences, Karolinska Institutet Norrbacka, 7th floor, SE-171 76 Stockholm, Sweden. (Email: firstname.lastname@example.org)