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

Background: 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. Methods: 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. Results: 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; Conclusions: 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.