Alcohol consumption and
T. gondii exposure have been individually associated with suicidal behavior. However, there is a lack of information about the association between
T. gondii exposure and suicidal behavior in persons with alcohol consumption. In the current study, we assessed the association between
T. gondii exposure and suicidal behavior in a sample of people with alcohol consumption in Durango, Mexico. We found a significantly higher seroprevalence of
T. gondii infection in individuals with suicidal ideation than in individuals without suicidal ideation. The 15.7% seroprevalence of
T. gondii infection found in individuals with suicidal ideation in the current study is also higher than the one (6.1%) reported in the general population of Durango City [
25]. Results thus suggest that
T. gondii exposure is associated with suicidal ideation in individuals with alcohol consumption. This association was observed in women and individuals aged ≤30 years and >50 years. Our results are in line with another report on the association between
T. gondii exposure and suicidal behavior. In a study of children and adolescents aged 11 to 18 years with depression, investigators found that seropositivity to
T. gondii was associated with suicidal ideation [
26]. In contrast, our results conflict with a negative association between
T. gondii exposure and suicidal ideation in psychiatric patients suffering from mental and behavioral disorders due to psychoactive substance use [
27]. However, in that study, only 38 patients with alcohol use were studied. In a National Health and Nutrition Examination Survey with data collected between 2009 and 2012 that included subjects aged 20 to 80 years in the USA, researchers found no association between suicidal ideation and anti-
T. gondii antibody titer [
28]. Differences in the association among the studies could be due to differences in the characteristics of the study population. We studied only people with alcohol consumption whereas researchers in the American survey studied the general population. In addition, risk factors for
T. gondii infection and suicidal behavior might be different among the study populations. In the present study, exposure to
T. gondii was not associated with suicidal ideation in the middle age group (31–50 years). It is unclear why there was not an association in this age group. It raises the question of whether this age group could be more resistant to the possible behavioral effects induced by
T. gondii than the younger and older age groups. With respect to suicide attempts, we found an association between
T. gondii seropositivity and suicide attempts in women but not in men or the whole population studied. It is not clear why this association was found in women but not in men. It is possible that the greater association of
T. gondii exposure and suicidal behaviors found more in women rather than in men could be due to the difference in risk factors, such as type of work, diet, contact with animals, and others among the gender groups. The 9.6% seroprevalence of
T. gondii infection found in individuals with suicide attempts in the current study is slightly higher than the one (6.1%) reported in the general population of Durango City [
25]. The lack of association between suicide attempts and
T. gondii seropositivity found in the whole study population in this survey agrees with results found in other studies. A lack of association between
T. gondii seropositivity and suicide attempts was reported in patients with mood disorders in the USA [
13] and in psychiatric outpatients in Mexico [
15]. In contrast, in a study in Turkey, researchers found a significantly higher rate of
T. gondii seropositivity in suicide attempters than in healthy volunteers [
29]. On the other hand, the association between
T. gondii exposure and suicide attempts in women found in the current study agrees with that found in a study in the USA where researchers observed a positive relationship between rates of infection with
T. gondii and suicide in women of postmenopausal age [
14]. In a study of schizophrenic patients in Iran, investigators found a lower rate of suicide attempts in
T. gondii seropositive male patients than in seronegative ones [
30]. In the present study, no association between the frequency of high anti-
T. gondii IgG antibody levels and suicide attempts was found. This result conflicts with those reported in other studies. An association between the frequency of high anti-
T. gondii antibody levels and suicide attempts were found in psychiatric outpatients in Mexico [
15], patients with recurrent mood disorders in the USA [
13], and schizophrenic patients younger than 38 years in Germany [
17]. The difference in the findings among the studies could be due to differences in the characteristics of the participants among the studies. It seems that the association between high anti-
T. gondii antibody levels and suicide attempts is more readily observed in psychiatric patients than in people with alcohol consumption. In the current study, no association between
T. gondii seropositivity or serointensity and number of suicide attempts was found. The lack of this association was also reported in a study of patients with recurrent mood disorders [
13]. In contrast, a study in psychiatric outpatients found that the seroprevalence of
T. gondii infection increased with the number of suicide attempts [
15]. Interestingly, we found that the frequency of high anti-
T. gondii antibodies was significantly higher in individuals with wrist cuts than in individuals who used other methods for suicide attempts. Further research to determine the association between
T. gondii serointensity and methods for suicide attempts should be conducted.
This study has some limitations: (1) we considered a qualitative (history of alcohol consumption) rather than a quantitative (number and type of alcoholic drinks) criterium for enrollment of participants; and (2) we could not trace back the date of infection and correlated it with suicidal behavior. Therefore, further research to determine the relationship between T. gondii exposure and: (1) the quantity of alcohol consumption, and (2) the time of having a suicidal behavior episode is needed. The association of suicidal behavior and T. gondii exposure found in the present study should not be concluded as categorical due to the possible presence of interactions of different risk factors and the absence of knowledge and characteristics that would be important to determine the certainty of this epidemiological link. Additional and more complete studies to confirm the association between T. gondii exposure and suicidal behavior in alcohol consumers should be conducted.