LAUSR

Abstract Background Coenzyme Q10 (CoQ10) is an endogenous compound that is essential for energy production within the mitochondria and also functions as a potent anti-oxidant, inhibiting oxidative stress and damage. Often deficits in CoQ10 are associated with fatigue, and cognitive and psychological impairment. In light of its many functions, CoQ10 supplementation to minimise decline and improve symptoms has been investigated in multiple disorders including neurological and neuropsychiatric disorders, with results indicating positive effects on fatigue, cognitive impairment and affective difficulties for disorders such as bipolar disorder and chronic fatigue syndrome. There is also evidence of mitochondrial dysfunction in schizophrenia. In light of this evidence, the current study aimed to investigate the potential effect of CoQ10 supplementation on 1) cognitive function and 2) psychological and physical health in schizophrenia and schizoaffective disorder. Methods A double blind, randomised, placebo controlled study was conducted to assess the effects of CoQ10 supplementation (300mg/day) on cognitive, psychological and physical variables in 70 patients with schizophrenia and schizoaffective disorder. The effects of CoQ10 supplementation were compared to placebo at 3 and 6 months. Plasma CoQ10 was measured at all time points, along with measures of mitochondrial function (via plasma lactate concentration). Sensitivity analysis followed an intention to treat approach that used multiple imputations to account for missing values. Results Overall there was no effect of CoQ10 supplementation on cognitive outcome measures. This is despite observing an increase in plasma CoQ10 concentration in the CoQ10 group compared to the placebo. CoQ10 supplementation also had no effect on mitochondrial function, energy, psychological symptoms, quality of life, functional status, physical activity or blood pressure at either time point. Discussion There is considerable evidence that mitochondrial dysfunction is present in patients with schizophrenia and schizoaffective disorder, and this dysfunction is implicated in the manifestation of cognitive impairment and clinical symptoms. CoQ10 can be taken as a nutritional supplement with minimal side effects to target mitochondrial dysfunction via promoting ATP generation and increasing antioxidant capacity. However, we found no effect of CoQ10 supplementation on any variable under investigation. It is possible that CoQ10 might act as a protective agent against exacerbated oxidative stress in these patients, and future studies might be warranted to examine this possibility. However, the current data is conclusive that CoQ10 supplementation does not ameliorate existing deficits in schizophrenia. These findings are translatable to clinical and community settings.