The metabolic syndrome is a constellation of vascular risk factors including abdominal obesity, hypertension, diabetes, hypertriglyceridaemia and low high density lipoprotein cholesterol. The aim of the study was to explore the link between the metabolic syndrome and its components, and psychosis in Alzheimer's disease. The participants were selected from the Human Serum Metabolome Project. 246 participants with Alzheimer's disease were assessed at baseline and 151 were followed up a year later. The neuropsychiatric inventory was used to capture information about psychiatric symptoms including delusions and hallucinations. The vascular risk factors were determined from the history from the participant and carer; abdominal obesity however was measured during the study. Hypertriglyceridaemia and high density lipoprotein cholesterol data were unavailable and so the study focuses on the link between the metabolic syndrome components of obesity, hypertension and diabetes, and psychosis in Alzheimer's disease. Although not part of the metabolic syndrome criteria, a history of hypercholesterolaemia was used in conjunction with the available metabolic syndrome components and the link between the resulting vascular syndrome and psychosis in Alzheimer's disease was studied. Two measure of psychosis were used for the research. First of all, a factor representing psychosis was derived by factor analysis of the neuropsychiatric inventory data. Secondly, a direct measure of psychosis using the delusions and hallucinations items from the neuropsychiatric inventory was used.Cross-sectional and longitudinal analyses were conducted. The majority of the analyses conducted failed to find a significant link between the measures. Male sex, a lower Mini Mental State Examination score as well as the use of antipsychotics and memantine were found to be significantly associated with psychosis at baseline. Overall this study does not support the link between the metabolic syndrome or its components and psychosis in Alzheimer's disease. Future research looking at subsets of Alzheimer's patients with more clearly defined lipid triglyceride and high density lipoprotein cholesterol data will be useful.