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Delusional Disorder (DD):
- Characterized by the presence of one or more delusions for a duration of one month or longer.
- Does not typically include hallucinations, but if they occur, they are related to the delusional theme.
- Daily functioning is not significantly impaired, and behavior is not notably odd or bizarre outside of the delusions.
- Delusions are often plausible and could be about situations that could occur in real life, such as being followed, poisoned, infected, loved at a distance, or deceived by a spouse or lover.
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Schizophreniform Disorder:
- Similar symptoms to schizophrenia but the duration of the disorder is shorter, ranging from one to six months.
- Diagnosis may lead to a later diagnosis of schizophrenia if symptoms persist beyond six months.
- Impairment in social and occupational functioning may occur, but it is not required for diagnosis.
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Schizophrenia:
- A chronic and severe mental health disorder where individuals may experience delusions, hallucinations, disorganized speech, disorganized or catatonic behavior, and negative symptoms (such as reduced emotional expression or avolition).
- Symptoms must be present for a significant portion of time during a one-month period, with some level of disturbance persisting for at least six months.
- Schizophrenia can significantly impair personal, social, and occupational functioning.
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Key Differences:
- The primary difference lies in the duration and severity of symptoms, with delusional disorder being more focused on delusions without the broader range of psychotic symptoms seen in schizophrenia.
- Schizophreniform disorder serves as a sort of intermediate diagnosis, where the symptom duration is longer than brief psychotic episodes but has not yet met the chronic criterion of schizophrenia.
- Age of onset can also differ, with schizophrenia often being diagnosed in late adolescence to early adulthood, while delusional disorder is more commonly diagnosed in middle to late adulthood.