The Role of Tryptophan Depletion on Depression in HIV-infected Ugandans

This morning at Mbarara University of Science and Technology in Uganda, Dr. Pricsella Martinez of UC Berkley gave a talk on the “Reversal of IDO-induced Tryptophan Catabolism to Improve Depression in ART-treated HIV-infected Ugandans.” She offered evidence to suggest that in addition to social determinants such as discrimination and stigma, immunological mechanisms might contribute to depression associated with HIV infection. In the developed world, HIV infected patients have decreased levels of the amino acid tryptophan despite evidence of adequate dietary consumption [1]. This problem is exacerbated in Uganda where a typical diet contains less than the recommended amount of protein [2]. Martinez and others sought to determine if HIV related tryptophan catabolism increases depression by depleting tryptophan that would be used for serotonin production in healthy adults. They sampled the Uganda AIDS Rural Treatment Outcomes (UARTO) cohort to evaluate tryptophan catabolism as a potential indicator of depressive symptoms over one year. This analysis showed a strong association between tryptophan depletion and depression in HIV-infected Ugandans. In this cohort, when individuals were treated with antiretroviral therapy (ART), depression symptoms declined and tryptophan levels increased significantly [3]. While this certainly does not establish causality, these data offer a contributing biological explanation for HIV associated depression. However, a limitation to this analysis is a lack of baseline assessment of depression in the individuals sampled. Additionally, there was no evaluation of the impact that treatment in general may have on depressive symptoms. It is well established that receiving medical care of any sort—particularly for HIV—has a significant impact on and individual’s outlook and quality of life [4]. Nonetheless, this study draws attention to the vital role of nutrition and treatment of mental health in HIV positive individuals in rural Uganda. The speaker plans to confirm these findings with a randomized controlled intervention targeting protein consumption to see if increasing tryptophan may paly a role in mitigating HIV associated depression.

1. Murray MF (2003). “Tryptophan depletion and HIV infection: a metabolic link to pathogenesis” The Lancet Infectious Diseases – Volume 3, Issue 10.

2. http://www.fao.org/ag/agn/nutrition/uga_en.stm

3. Martinez, P.et al. Reversal of IDO-induced Tryptophan Catabolism May Mediate Antiretroviral Therapy-related Improvements in Depression in HIV-infected Ugandans. Program and Abstracts of the 19th Conference on Retroviruses and Opportunistic Infections, Seattle, WA, Abstract #462. 2012.

4. Sherbourne CD et al (2000). “Impact of Psychiatric Conditions on Health-Related Quality of Life in Persons With HIV Infection” Am J Psychiatry 2000;157:248-254.

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