Background: Alzheimer disease (AD), a chronic progressive neurodegenerative disorder, has a mainly unknown multifactorial etiology. Neuroinflammatory mechanisms might contribute to the cascade of events leading to neuronal degeneration. Central nervous system infections have been previously suggested as possible etiological agents in the development of sporadic AD. Toxoplasmosis can be associated with various neuropsychiatric disorders. In this study, we aimed to investigate the possible association between toxoplasma infection and AD.