Associations Between Mental Disorders in Donors and Matched Recipients of Hematopoietic Stem Cell Transplants: A Population-Based Cohort Study

Immunological mechanisms have been implicated in the development of mental disorders, and interestingly, case reports have suggested that hematopoietic stem cell transplantation (HSCT) can both transmit and cure psychotic disorders by replacing immune progenitor cells. Using Danish registers, we followed patients who received HSCT from donors with a psychiatric diagnosis or psychotropic medication use. We assessed risk of incident mental disorders or psychotropic medication use compared with recipients with unaffected donors. We identified 464 donor-recipient pairs (51.3% male recipients). All donor-recipient pairs were related. Receiving HSCT from a donor with a psychiatric history was not significantly associated with incident psychiatric diagnoses (hazard rate ratio [HRR] 2.79, 95% CI, 0.83–9.39; p = .098) or incident use of psychotropics (HRR 1.43, 95% CI, 0.91–2.24; p = .118). Subgroup analysis showed an increased risk of antipsychotic use, which remained significant after adjusting for confounders (HRR 4.73, 95% CI, 1.26–17.78; p = .021); however, this was based on a small number of cases. For depression and antidepressant use, data were available to perform a meta-analysis of our and one additional study, which showed no significant difference (HRR 1.24, 95%, CI 0.66–2.35). Receiving HSCT from a donor with a psychiatric history did not affect risk of mental disorders. An increased risk of antipsychotic use was observed only in subgroup analyses; however, the exploratory nature of the study, the limited sample size, and family relationship between donors and recipients do not allow for causal conclusions, and external replication studies are warranted. Immunological disturbances have been implicated in the development of mental disorders, and prior case reports have suggested that stem cell transplants can both cause and cure psychotic disorders. Using data on stem cell transplants in Denmark, we did not find evidence of a risk of transmitting mental disorders through transplantation. However, risk of antipsychotic use was elevated in recipients who had donors with antipsychotic use.