Objective: Viral infections have been previously associated with psychiatric disorders. This work aimed to study the relationship between the human T-cell lymphotropic virus type 1 (HTLV-1) and depression.
Method: A case-control study with prevalent cases was conducted from April 2004 to June 2005. Participants were from a public transfusion center in Belo Horizonte, Brazil. The base population was composed of blood donor candidates infected with HTLV-1 (asymptomatic carriers), followed-up in a cohort study. As a control group, HTLV-1 seronegative blood donors were selected in a random fashion. Study participants underwent psychiatric evaluation using a structured diagnostic instrument, the Mini International Neuropsychiatry Interview (MINI), to estimate the rate of depression. The interviewer was unaware of participants' HTLV-1 serostatus. The co-variables studied were gender, age, formal education, personal income, and the presence of other psychiatric diagnoses. Logistic regression was used to examine the relation between HTLV-1 infection and depression.
Results: The final sample was composed of 74 individuals infected with HTLV-1 and 24 uninfected controls. The rate of depression was significantly higher in HTLV-1 carriers when compared with controls (39% vs. 8%; p-value = 0.005). HTLV-1 infection was independently associated with depression (OR = 6.17; CI 95% = 1.32-28.82).
Conclusions: The results showed a higher rate of depression in HTLV-1 infected individuals. It was not possible to determine whether depression was related to knowledge of chronic retroviral infection or related to a biological effect of the retroviral infection.