Although anger and hostility are commonplace, shame, depression, and avoidant behavior are even more characteristic. Suicide, apparently motivated by anguish, is not uncommon. Somatic delusional disorders are quite difficult to treat, as evidenced by a treatment success rate of approximately one-third.
Treatment with antipsychotic drugs have been reported to be useful in the
management. Delusional disorder is thought to be fairly stable and less than 25% of all patients with delusional disorder progress to schizophrenia.
The relationship between delusional disorder and schizophrenia is not of inevitable progression from the former to the latter. Studies have found that while schizophrenia spectrum disorders were more prevalent in the biologic relatives of the schizophrenic adoptees, the same was not the case for delusional disorder thus pointing out that from a genetic perspective, delusional disorder may not be part of the schizophrenia spectrum. These findings were supported by another study that found delusional disorder (compared with schizophrenia, affective illness and psychotic disorders not otherwise specified) as the least prevalent (2.7%) among the probands of patients with schizophrenia