A longitudinal study of schizophrenia- and affective spectrum disorders in individuals diagnosed with a developmental language disorder as children.

The prevalence and types of schizophrenia- and affective spectrum disorders were studied in 469 individuals with a developmental language disorder (DLD), assessed in the same clinic during a period of 10 years, and 2,345 controls from the general population. All participants were screened through the nationwide Danish Psychiatric Central Register (DPCR). The mean length of follow-up was 34.7 years, and the mean age at follow-up 35.8 years. The results show an excess of schizophrenia spectrum disorders (F20-F29) within participants with DLD when compared with controls from the overall population (6.4% vs. 1.8%; P < 0.0001). For schizophrenia (F20.x) the respective figures were 3.8% versus 1.1%; P = 0.0001. The variable degree of expressive language disorder was significantly associated with a schizophrenia spectrum disorder diagnosis in the DPCR. There was no significant increase in affective spectrum disorders (F30-F39) in the DLD case group (3.4% vs. 2.0%; P = 0.05). Our results provide additional support to the notion that DLD is a marker of increased vulnerability to the development of schizophrenia spectrum disorders.