Toxoplasma seropositivity and depression: a case report

BACKGROUND: The association between toxoplasmosis and psychiatric disorders has been reported in a few anecdotal reports. CASE PRESENTATION: A case of depression with toxoplasma seropositivity is presented. The patient with depression showed poor response to antidepressants, for which he was investigated and was found positive on the serological test for the toxoplasma. The response to antidepressant treatment improved only after adequate treatment for toxoplasma. CONCLUSIONS: The case suggests a probable association between toxoplasmosis and depression

The Neurotropic Parasite Toxoplasma Gondii Increases Dopamine Metabolism

The highly prevalent parasite Toxoplasma gondii manipulates its host's behavior. In infected rodents, the behavioral changes increase the likelihood that the parasite will be transmitted back to its definitive cat host, an essential step in completion of the parasite's life cycle. The mechanism(s) responsible for behavioral changes in the host is unknown but two lines of published evidence suggest that the parasite alters neurotransmitter signal transduction: the disruption of the parasite-induced behavioral changes with medications used to treat psychiatric disease (specifically dopamine antagonists) and identification of a tyrosine hydroxylase encoded in the parasite genome. In this study, infection of mammalian dopaminergic cells with T. gondii enhanced the levels of K+-induced release of dopamine several-fold, with a direct correlation between the number of infected cells and the quantity of dopamine released. Immunostaining brain sections of infected mice with dopamine antibody showed intense staining of encysted parasites. Based on these analyses, T. gondii orchestrates a significant increase in dopamine metabolism in neural cells. Tyrosine hydroxylase, the rate-limiting enzyme for dopamine synthesis, was also found in intracellular tissue cysts in brain tissue with antibodies specific for the parasite-encoded tyrosine hydroxylase. These observations provide a mechanism for parasite-induced behavioral changes. The observed effects on dopamine metabolism could also be relevant in interpreting reports of psychobehavioral changes in toxoplasmosis-infected humans

Sex determines which section of the SLC6A4 gene is linked to obsessive–compulsive symptoms in normal Chinese college students

Previous case-control and family-based association studies have implicated the SLC6A4 gene in obsessive-compulsive disorder (OCD). Little research, however, has examined this gene's role in obsessive-compulsive symptoms (OCS) in community samples. The present study genotyped seven tag SNPs and two common functional tandem repeat polymorphisms (5-HTTLPR and STin2), which together cover the whole SLC6A4 gene, and investigated their associations with OCS in normal Chinese college students (N = 572). The results revealed a significant gender main effect and gender-specific genetic effects of the SLC6A4 gene on OCS. Males scored significantly higher on total OCS and its three dimensions than did females (ps < .01). The 5-HTTLPR in the promoter region showed a female-specific genetic effect, with the l/l and l/s genotypes linked to higher OCS scores than the s/s genotype (ps < .05). In contrast, a conserved haplotype polymorphism (rs1042173| rs4325622| rs3794808| rs140701| rs4583306| rs2020942) covering from intron 3 to the 3' UTR of the SLC6A4 gene showed male-specific genetic effects, with the CGAAGG/CGAAGG genotype associated with lower OCS scores than the other genotypes (ps < .05). These effects remained significant after controlling for OCS-related factors including participants' depressive and anxiety symptoms as well as stressful life events, and correction for multiple tests. These results are discussed in terms of their implications for our understanding of the sex-specific role of the different sections of the SLC6A4 gene in OCD

Performance of the adolescent obsessive-compulsive scale in a community survey

Obsessive-compulsive behavior was studied in a cohort of N=570 subjects who had been assessed at three times between adolescence and young adulthood. Based on the Youth Self-Report (YSR) and the Young Adult Self-Report (YASR), the adolescent obsessive-compulsive scale (AOCS) was defined. At each of the three assessments, subjects scoring above the cut-off score of the 90th percentile of the AOCS were identified and compared to the rest of the sample serving as control group. The risk group was clearly more abnormal in both domains of internalizing and externalizing across time. Various psychiatric disorders in young adulthood were predicted by the AOCS. However, concomitant general psychopathology also contributed strongly to the prediction. Parent and youth agreement on group membership was rather low. Stability of group assignment across time was significantly increased. The AOCS is a promising instrument both for epidemiological and clinical studies. Its content and predictive validity deserves further studies

The analytical epidemiology of obsessive–compulsive disorder: risk factors and correlates

In this qualitative systematic review, we evaluate studies of the demographic, innate, and environmental risk factors and correlates associated with the development of Obsessive-Compulsive Disorder (OCD) in epidemiological samples. We found that a significant proportion of the studies indicate that late adolescence is a period of increased vulnerability for the development of OCD; that OCD affects predominantly female adults and male children and adolescents; that those who are unmarried or abusing drugs are more likely to present with OCD; that OCD is a familial and genetic disorder, particularly when one considers symptom dimensions instead of categorical diagnosis and when the disorder begins at an early age; and that individuals with OCD from the community, like those seen in clinical settings, may be especially prone to present psychiatric conditions such as mood and anxiety disorders. Although there are plenty of data on the correlates and risk factors of OCD in epidemiological samples, more research is needed on other potential risk factors, including obstetrical and pregnancy problems, pre-morbid neurocognitive functioning, and streptococcal infections, among others