Memory impairment and latent toxoplasmosis; association, awareness and risk factors in a high Toxoplasma-seroprevalence community

Memory impairment (MI), happens when a person loses the ability to remember information and events they would normally be able to recall. Toxoplasmosis is one of the most important parasitic diseases involving the brain. Due to the localization of Toxoplasma gondii tissue cysts in brain and some related reports, the effect of toxoplasma on neurodegenerative diseases has been suggested.

The present study was conducted to investigate the probable association between MI and toxoplasmosis using serological and molecular techniques. The study population consisted of 87 Alzheimerchr(chr('39')39chr('39'))s patients (AP) and 87 healthy controls which were selected under the supervision of neurology consultant. The Toxoplasma-specific antibodies were measured using commercial ELISA kits. The desired region for Toxoplasma B1 gene was amplified by using specific primers and a thermocycler. Specificity of primers was confirmed by direct sequencing, aligning and phylogenetic analysis of the amplicons.

Prevalence of toxoplasmosis in AP and control group was 66.6% and 56.3% (P=0.99) and 52.8% and 40.2% (P=0.229) using ELISA and PCR respectively. Despite the higher prevalence of toxoplasmosis in AP compared with the controls, a significant relationship was not found between MI and toxoplasmosis. The multiple sequence alignment of T. gondii isolates revealed a common haplotype. The significant relationship between some variables and toxoplasmosis as well as the MI could reveal the risk factors for MI.

These results provide fresh insights into the ambiguous association between T. gondii infection and MI. As a probable or concomitant risk factor, toxoplasmosis could induce the MI, principally in patients with the chronic or latent infection.