Delusions can suggest several diseases such as schizophrenia, schizophreniform disorder, a brief psychotic episode, mania, depression with psychotic features, or delusional disorders. One can differentiate delusional disorders from schizophrenia for example by the age of onset for delusional disorders being older with a more complete and unaffected personality, where the delusion may only partially impact their life and be fairly encapsulated off from the rest of their formed personality. I.e. believing that a spider lives in their hair, but this belief not affecting their work, relationships, or education. Whereas schizophrenia typically arises earlier in life with a disintegration of personality and a failure to cope with work, relationships, or education.