2009 · Article
Rare Somatic Comorbidity in Patients with Schizophrenia
Documentary study of rare and negative comorbidity patterns between schizophrenia and selected somatic diseases
How to cite this article
Shishkov, R., Georgieva, A., & Georgieva, M. (2009). Rare somatic comorbidity in patients with schizophrenia. Proceedings of the Union of Scientists – Varna, Medicine and Ecology Series, XIV(2), 55–57.
Extended Structured Summary
Introduction
The relationship between schizophrenia and somatic disease is a clinically and pathogenetically important problem. Some studies have reported lower-than-expected rates of selected physical diseases among people with schizophrenia, particularly certain cancers and rheumatoid arthritis.
Such observations have generated hypotheses involving genetic, immunological or other biological mechanisms that might contribute to schizophrenia while simultaneously modifying susceptibility to particular somatic disorders.
Aim
To determine the frequency of cancer, rheumatoid arthritis — both seropositive and seronegative — and non-atopic bronchial asthma among patients with schizophrenia and to examine combinations of these conditions.
Material and methods
The study examined patients treated at St Marina University Hospital, Varna, during 2002–2009. A documentary method based on review of medical histories was used.
The analysis covered large clinical groups: 14,279 patients with cancer, 1,891 patients with schizophrenia, 1,591 patients with bronchial asthma and 1,458 patients with rheumatoid arthritis.
Cancer and schizophrenia
The findings support earlier observations of lower comorbidity between cancer and schizophrenia. The study treats this pattern as a reason for further investigation of possible biological mechanisms rather than evidence of a proven protective effect.
Rheumatoid arthritis and schizophrenia
A lower comorbidity between rheumatoid arthritis and schizophrenia was also observed, consistent with the negative association described in previous literature.
This relationship is of particular interest in view of immunological and autoimmune hypotheses concerning some pathogenetic mechanisms of schizophrenia.
Non-atopic bronchial asthma: the most unusual finding
A particularly notable result was that non-atopic bronchial asthma was extremely rarely combined with schizophrenia. The authors note that this observation had received little or no attention in the previous literature.
Differences in disease pathogenesis — including infectious-allergic mechanisms in asthma and autoimmune hypotheses in schizophrenia — are discussed as possible directions for further research.
How “negative comorbidity” should be interpreted
A lower frequency of one disease among patients with another does not automatically establish a protective or causal biological relationship. Diagnostic, behavioural, treatment-related, genetic, immunological and methodological explanations are all possible.
The findings therefore generate hypotheses rather than proving a specific mechanism.
Scientific and clinical relevance
- supports previous observations of lower cancer comorbidity in schizophrenia;
- reinforces evidence of a negative association between schizophrenia and rheumatoid arthritis;
- identifies the rare combination with non-atopic bronchial asthma as an understudied phenomenon;
- points toward possible immunological and genetic mechanisms;
- demonstrates the value of large hospital datasets for generating clinically relevant hypotheses.
Main contributions
- examines four large clinical populations over 2002–2009;
- compares schizophrenia with three different categories of somatic disease;
- confirms two previously discussed negative-comorbidity patterns;
- adds a novel observation concerning exceptionally rare comorbidity with non-atopic bronchial asthma;
- identifies directions for subsequent pathogenetic and epidemiological research.
Conclusions
The relationship between schizophrenia and somatic disease is not limited to increased overall physical morbidity. Some conditions show unexpectedly low levels of comorbidity, potentially offering clues to shared or opposing biological mechanisms.
The most distinctive finding is the rare combination of schizophrenia with non-atopic bronchial asthma, which warrants independent replication and more detailed investigation.