Schizophrenia, narcolepsy, and HLA-DR15, DQ6

Area of Science:

• Neuroscience
• Immunogenetics
• Psychiatry

Background:

• A known association exists between HLA-DR2/DQ1 and narcolepsy-cataplexy, with HLA-DR15/DQ6 identified as a subdivision.
• Narcolepsy symptoms, including daytime hallucinations, can overlap with psychotic symptoms seen in schizophrenia.
• Some individuals with narcolepsy may be misdiagnosed with schizophrenia due to severe hallucinations and delusions.

Purpose of the Study:

• To investigate the prevalence of narcolepsy-associated antigens (NAA) in patients diagnosed with schizophrenia.
• To determine if NAA presence correlates with symptom severity and hospitalization rates in schizophrenia patients.
• To explore the potential for narcolepsy to present as schizophrenia.

Main Methods:

• A case-control study comparing 56 inpatient schizophrenics with 56 healthy controls for NAA frequency.
• Polysomnography was conducted on a subset of patients to identify true narcolepsy cases.
• Comparison of Brief Psychiatric Rating Scale (BPRS) scores and hospitalization history between NAA-positive and NAA-negative schizophrenic subgroups.

Main Results:

• Narcolepsy-associated antigens (NAA) were found 3.89 times more frequently in schizophrenic patients than in controls.
• Two patients were confirmed to have narcolepsy, and their psychosis symptoms improved with narcolepsy treatment.
• NAA-positive schizophrenic patients exhibited significantly higher BPRS scores and more hospitalizations compared to NAA-negative patients.

Conclusions:

• Narcolepsy can present with symptoms that simulate schizophrenia, potentially leading to misdiagnosis.
• The presence of HLA-DR15/DQ6 antigens in non-narcoleptic schizophrenic patients identifies a subgroup with potentially more severe illness requiring further investigation.
• These findings highlight the importance of considering narcolepsy in the differential diagnosis of schizophrenia, particularly in patients with specific HLA types.