The prevalence of human thymic lymphoid follicles is lower in suicides

In an autopsy study we determined the prevalence of thymic lymphoid follicles in 311 accident victims in whom the time interval between accident and death was known. We found that the prevalence decreased abruptly in those surviving 48 h or more (P=0.000008). We then compared the prevalence in 271 accident and 168 suicide victims, all of whom had died less than 48 h after the incident and found that the prevalence was significantly lower in the suicide group (P=0.03). We conclude that this difference may be related to the effect on the thymus of high levels of psychological stress likely to have been experienced by the suicides in the days prior to the act. The use of the term hyperplasia to indicate the presence of lymphoid follicles in the thymus and the methodology appropriate for determining the prevalence of thymic lymphoid follicles are discussed.