Schizophrenia

According to the Society for Neuroscience: "Schizophrenia is a devastating brain disorder that torments sufferers with hallucinations, delusions, disordered thinking patterns, and memory deficits. It is especially tragic because it usually strikes during the late teens, 20s, or early 30s. In the past, many individuals with schizophrenia became permanently lost to the social withdrawal and other behavioral
problems characteristic of this disease."

Unfortunately, this definition fails to differentiate between schizophrenia and DID. One of the important differences is that schizophrenics perceive their hallucinations as having an external origin, while those with DID perceive their voices and flashbacks as having an internal origin. Thought disturbance is prominent in schizophrenia, while any apparent thought disturbance in DID results from intrusions by alters' thoughts.