Treatment of Cognitive and Negative Symptoms in Schizophrenia With N-acetylcysteine

The purpose of this study is to attempt to treat cognitive and negative symptoms of schizophrenia, with the nutritional supplement N-acetylcysteine (NAC). Schizophrenia is a chronic mental disorder that affects approximately 65 million people worldwide, and causes significant disability and suffering. Patients with schizophrenia often hear voices and have persecutory delusions. Though these are the most recognizable features of the illness, the deficits most closely linked to disability are known as cognitive deficits and negative symptoms. Cognitive abilities refer to the ability to perform mental tasks that require focus and attention, and also include memory and verbal skills. Negative symptoms refer to a lack of interest in the world, and decreased social interactions. In our study, the investigators aim to improve these symptoms and deficits by targeting the glutamate system. Glutamate is the major excitatory neurotransmitter in the brain, and its regulation is abnormal in schizophrenia: glutamate levels are too low at some receptors, and too high at others. As well, free radicals surrounding glutamate receptors also interfere with their proper function. N-acetylcystine (NAC) is a safe and widely-available dietary supplement that may restore glutamate to its correct levels in the brain, and may also help protect the brain from antioxidant damage. In our study, patients with schizophrenia will be randomly assigned to receive either NAC or placebo for 8 weeks. Brain levels of glutamate and an important antioxidant, glutathione, will be measured before and after treatment, using a neuroimaging technique known as magnetic resonance spectroscopy. Cognitive and negative symptoms will also be assessed before, during and after treatment. The investigators hypothesize that glutamate and glutathione will be normalized in patients' brains, and that their negative and cognitive symptoms will be improved, too.