Translating Neurobiology to the Treatment of Dual Diagnosis: The Example of Nicotinic Receptors and Neurocognitive Endophenotypes in Schizophrenia

Cardiometabolic risk factors in young people at ultra-high risk for psychosis: A systematic review and meta-analysis

BACKGROUND

The physical health of people with schizophrenia is poor, and associated with increased morbidity and mortality. Unhealthy lifestyles and side-effects of antipsychotic medication contribute to cardiometabolic dysfunction. Yet it is unclear when this unhealthy profile starts. We aimed to see if people at ultra-high risk for psychosis (UHR) have increased rates of cardiometabolic risk factors.

METHOD

An electronic search of MEDLINE, PsycINFO, Embase and the Cochrane Central Register of Controlled Trials was conducted on 1st May 2015 using terms associated with the ultra-high risk state and health. Eligible studies were peer-reviewed English language research articles with populations that met at-risk diagnostic criteria and reported cardiometabolic risk factors. A meta-analysis was conducted on smoking data, the cardiometabolic risk factor that yielded the most studies.

RESULTS

Forty-seven eligible studies were identified. UHR samples had low levels of physical activity, and high rates of smoking and alcohol abuse compared with controls. No differences were found for body mass index. An overall pooled rate of smoking for UHR participants was 33% (95% CI=0.24-0.42) and significantly more UHR individuals smoked compared with controls with a pooled odds ratio of 2.3 (P<0.05; 95% CI=-1.48-3.48).

CONCLUSIONS

UHR samples display cardiometabolic risk factors which are largely modifiable. The UHR phase is an important opportunity for early intervention services to improve physical health.

Does chronic nicotine consumption influence visual backward masking in schizophrenia and schizotypy?

Nicotine consumption is higher for people within the schizophrenia spectrum compared to controls. This observation supports the self-medication hypothesis, that nicotine relieves symptoms in, for example, schizophrenia patients. We tested whether performance in an endophenotype of schizophrenia (visual backward masking, VBM) is modulated by nicotine consumption in i) smoking and non-smoking schizophrenia patients, their first-degree relatives, and age-matched controls, ii) non-smoking and smoking university students, and iii) non-smoking, early and late onset nicotine smokers. Overall, our results confirmed that VBM deficits are an endophenotype of schizophrenia, i.e., deficits were highest in patients, followed by their relatives, students scoring high in Cognitive Disorganisation, and controls. Moreover, we found i) beneficial effects of chronic nicotine consumption on VBM performance, in particular with increasing age, and ii) little impact of clinical status alone or in interaction with nicotine consumption on VBM performance. Given the younger age of undergraduate students (up to 30 years) versus controls and patients (up to 66 years), we propose that age-dependent VBM deficits emerge when schizotypy effects are targeted in populations of a larger age range, but that nicotine consumption might counteract these deficits (supporting the self-medication hypothesis).