Linking nervous and immune systems in psychiatric illness: A meta-analysis of the kynurenine pathway.

Tryptophan is an essential amino acid absorbed by the gut depending on a homoeostatic microbiome. Up to 95% of unbound tryptophan is converted into tryptophan catabolites (TRYCATs) through the kynurenine system. Recent studies identified conflicting associations between altered levels of TRYCATs and genetic polymorphisms in major depressive disorder (MDD), schizophrenia (SCZ), and bipolar disorder (BD). This meta-analysis aimed to understand how tryptophan catabolic pathways are altered in MDD, SCZ, and BD. When compared to healthy controls, participants with MDD had moderately lower levels of tryptophan associated with a moderate increase of kynurenine/tryptophan ratios and no differences in kynurenine. While significant differences were found in SCZ for any of the TRYCATs, studies on kynurenic acid found opposing directions of effect sizes depending on the sample source. Unique changes in levels of TRYCATs were also observed in BD. Dynamic changes in levels of cytokines and other immune/inflammatory elements modulate the transcription and activity of kynurenine system enzymes, which lastly seems to be impacting glutamatergic neurotransmission via N-methyl-D-aspartate and α-7 nicotine receptors.

Ending AIDS as a Public Health Threat: Treatment-as-Usual Risk Reduction Services for Persons With Mental Illness in Brazil.

OBJECTIVE: Persons with mental illness have higher HIV infection rates than the general population. Little is known about whether care systems for this population are effectively participating in global efforts to end AIDS as a public health threat. This study examined treatment-as-usual HIV risk reduction services within public mental health settings. METHODS: The authors interviewed 641 sexually active adults attending eight public psychiatric clinics in Rio de Janeiro about participation in a sexual risk reduction program, HIV testing, HIV knowledge, and sexual behaviors. RESULTS: Nine percent reported participation in a risk reduction program in the past year, and 75% reported having unprotected sex in the past three months. Program participants had greater HIV knowledge (p=.04) and were more likely to have had HIV testing in the past three months (p=.02), compared with nonparticipants. Participation was not associated with sexual behaviors. CONCLUSIONS: Including persons with mental illness in efforts to end AIDS requires a greater commitment to implementing effective interventions in public mental health systems.

Why the Treatment of Mental Disorders Is an Important Component of HIV Prevention among People Who Inject Drugs.

People who inject drugs are more likely to be HIV positive and to have a mental disorder than the general population. We explore how the detection and treatment of mental illness among people who are injecting drugs are essential to primary and secondary prevention of HIV infection in this population. Aside from opioid addiction, few studies have been conducted on the links between mental disorders and injection-drug use. However, independent of the injection-drug use literature, a growing number of studies demonstrate that untreated mental illness, especially depression and alcohol/substance use disorders, is associated with HIV-related risk behaviors, acquiring HIV infection, failure to access HIV care and treatment, failure to adhere to HIV care and treatment, and increased morbidity and mortality from HIV-related diseases and comorbidities. In our review of both the published literature and gray literature we found a dearth of information on models for providing care for both opioid addiction and other mental illnesses regardless of HIV status, particularly in low- and middle-income countries. We therefore make recommendations on how to address the mental health needs of HIV-positive people who inject drugs, which include the provision of opioid substitution therapy and integrated mental health, substance abuse, and HIV services.