Schizophrenia: a multisystem disease?

A multisystem disease is one that usually affects a number of organs and tissues during the course of the illness (Dorland, 2008). It has long been observed that some individuals with schizophrenia have levels of general physical illnesses in excess of that seen in the general population, but recent studies suggest that most people with schizophrenia have co-morbid physical disease and multiple related risk factors. Jones et al. (2004) reported that 74% of patients with schizophrenia had at least one chronic co-morbid medical condition. Bell et al. (2009) found that 90% of Medicaid recipients with schizophrenia had at least one major metabolic risk factor. Using a higher standard of at least three major risk factors (NCEP-ATP-III guidelines: abdominal obesity, hypertriglyceridemia, dyslipidemia, hypertension and hyperglycemia) approximately 40% of European patients and up to 51.6% patients with schizophrenia in the United States satisfy criteria for the metabolic syndrome (De Hert et al., 2009; Meyer et al., 2005). In the METEOR study, the largest analysis of risk factors in schizophrenia and related disorders reported that 69.9% had lipid disorders and 43.4% had hypertension (De Hert et al., 2008). Together this evidence suggests that most people with schizophrenia have a significant co-morbid physical illness and further the great majority have metabolic risk factors (Mitchell and Malone, 2006). Rates of co-morbidity appear to be influenced by the severity of psychiatric symptoms, the setting of study and nature of prescribed medication. Physical co-morbidity in turn has an impact upon quality of life, suicide attempts and mortality, even when suicide is eliminated (Heila et al., 2005; Hennekens et al., 2005; Joukamaa et al., 2006; Kolotkin et al., 2008). While core symptoms of schizophrenia usually first emerge in the late teens and early twenties, peripheral physical disease gradually increases with age (Bresee et al., 2010). Similarly metabolic risk factors are usually elevated at first episode but accumulate with time (Saddichha et al., 2008). Lifestyle and cardiovascular risk factors play an important role in the physical complications but they do not appear to account for the entire variance (Connolly and Kelly, 2005). Antipsychotic drugs certainly contribute to physical co-morbidity (Oriot et al., 2008), but this effect is likely to be magnified in a vulnerable population. All metabolic risk factors are important but we should give special attention to those that are potentially reversible. Recent research has highlighted some valuable insights in the following areas.