A Case-Control Study of Seroprevalence of Toxoplasma gondii in Dementia Patients in Arak and Hamadan, West of Iran

Toxoplasmosis is one of the common parasitic infections in the human population. It has been estimated that one out of every three persons is infected with this organism. The role of toxoplasmosis has been evaluated in neurological disorders such as migraine, schizophrenia, Parkinson, Alzheimer’s disease and recently, dementia. Dementia has a wide distribution in the elderly.

This study was conducted to determine the possible role of Toxoplasma infection in dementia patients in Arak and Hamadan cities, West of Iran.

In this case-control study, 100 dementia patients referring to hospital settings in Arak and Hamadan and 99 healthy controls were selected under the supervision of neurologists. Their blood samples were transferred to the Research Laboratory of Arak University of Medical Sciences under the cold chain. Serum specimens were isolated and frozen at -20°C until use. T. gondii IgG and IgM were analyzed in serum samples using Enzyme-Linked Immunosorbent assay.

The total prevalence of T. gondii infection among dementia patients and healthy controls were 59% (59/100) and 39.3% (39/99), respectively. A statistically significant difference was observed in the seroprevalence of toxoplasmosis between the case and control groups (P = 0.002). IgG seropositivity was higher among patients from Hamadan than among those from Arak (68% versus 50%). IgM seropositivity was determined in two patients from Arak. There was a significant correlation between the seroprevalence of toxoplasmosis and the presence of cats in their neighborhood and meat consumption.

The possible effect of T. gondii on dementia can lead to significantly higher seropositivity of IgG in dementia individuals than in controls. Control measures are essential to prevent toxoplasmosis, especially in people with dementia.