Autoimmunity is considered an uncommon but under-recognised cause of cognitive decline. Serum samples from 3,253 randomly selected subjects enrolled in the Hunter Community Study, aged 55-85 years, were assayed for thyrotropin stimulatory hormone, anti-thyroid peroxidase antibodies (TPO-Ab), anti-nuclear antibodies (ANA) and extractable nuclear antigens (ENA). Cognitive function was assessed using the Audio Recorded Cognitive Screen (ARCS) tool. TPO-Ab were found in 8.4% and ANA in 27.9% of the study population, of whom 3% had positive ENA findings. No relationship was found between the ARCS score and either TPO-Ab (coefficient = 0.133; 95% CI -0.20, 0.82, p = 0.616), ANA at a low (coefficient = 1.01; 95% CI -2.58, 0.55, p = 0.203) or a high titre (coefficient = -0.65; 95% CI -2.59, 1.28, p = 0.508), or ENA antibodies (coefficient = 5.12; 95% CI -0.53, 10.77; p = 0.076). Autoantibody findings are common in an aging population and are not associated with cognitive decline.