Schizophr Bull 2014; Advance online publication
medwireNews: A wide range of physical ailments that require hospital contact may contribute to an increased risk of schizophrenia, a study suggests.
“Generally, risks for schizophrenia were higher within the first years after a somatic contact but remained clearly elevated several years after”, the researchers write in Schizophrenia Bulletin.
The team studied 954,351 people born in Denmark between 1977 and 1993, of whom 4371 developed schizophrenia by 2009. In all, 95.6% had hospital contact for a somatic disease before being diagnosed with schizophrenia.
The incidence rate ratio (IRR) was 2.04 for schizophrenia among people with prior hospital contact versus those without, after accounting for calendar year, age and its interaction with gender, and individual somatic disease categories according to the World Health Organization International Classification of Diseases (ICD).
Hospital contact for almost all individual ICD categories was significantly associated with the later development of schizophrenia, with adjusted IRRs ranging from 1.14 for congenital malformations and chromosomal abnormalities to 2.26 for epilepsy when compared with no hospital contact for the specific condition.
“The uniformity of the associations observed in this study could potentially reflect many possible mechanisms”, say lead study author Holger Sørensen (Copenhagen University Hospital, Denmark) and colleagues.
“These might include genetic or physiological overlap, interacting immunological, behavioral, experiential, or social factors.”
Hospital contact for all disease categories was significantly associated with schizophrenia risk in a concurrent timeframe (0–4 years before schizophrenia diagnosis), with the exception of the diseases of blood (forming) organs, immunological disorders ICD category. However, this category was associated with schizophrenia in a delayed timeframe; the IRR for schizophrenia 5 years or more after hospital contact for this category of diseases was 1.29.
Other categories with a notable delayed effect, in addition to a concurrent effect, included epilepsy, digestive system diseases, genitourinary diseases, circulatory diseases and brain injury. A number of categories had a concurrent but not a delayed effect, including respiratory system diseases; endocrine, nutritional, metabolic diseases; and neoplasms.
“Future research could further examine the hypothesis that there are systemic underpinnings of schizophrenia and that some physical diseases might precipitate the onset or be associated with increased risk of schizophrenia”, concludes the team.