Background: Toxoplasma deprives host neuron cells from cholesterol and leads to its ability to potentiate dementia. ApoE intermediates neuronal transmission of cholesterol, which is a key constituent for axonal development, redesigning occasions that are important for education and synaptic arrangement, development of memory and repair of neuron. The aim of this work is to investigate the effect of ApoE genotypes on dementia associated with neurodegeneration in latent Toxoplasma gondii in elderly population. Methods: This study comprised: 133 patients with dementia (78 were positive for toxoplasma IgG and 55 were negative) and 95 subjects as control group without dementia (30 were positive for toxoplasma IgG and 65 were negative). All of them were subjected to a cognitive assessment, T. gondii seropositivity (ELISA) and determination of ApoE allelic forms (PCR). Results: The ApoE genotype distribution shows that the most predominant genotype is ApoE3/3 and the most widely recognized allele is E3. Both patients and control were further divided into Toxoplasma IgG positive group (n = 108) and Toxoplasma IgG negative group (n = 120). ApoE4 non carrier, ApoE 2/3 and ApoE 3/3 alleles have highly significant differences (P < 0.001) between dementia and non-dementia patients in Toxoplasma infected patients in comparison to non-infected ones. Conclusion: Toxoplasma positive patients have more risk to develop dementia regardless ApoE4 carriage. (C) 2017 Elsevier Ltd. All rights reserved.