From the Guidelines
A positive Antinuclear Antibody (ANA) test in a patient experiencing their first episode of psychosis is not a definitive indicator of an underlying autoimmune disorder, but rather a nonspecific marker that requires further evaluation in the context of clinical manifestations and other diagnostic criteria 1.
Key Considerations
- The positive likelihood ratio of ANA detection is low, especially when using a cut-off point of 1:80, and therefore, the correct diagnosis will primarily be based on individual clinical manifestations or characteristics 1.
- A positive ANA test may be associated with various autoimmune disorders, including Systemic Lupus Erythematosus (SLE), which can present with psychiatric symptoms, including psychosis 1.
- The diagnostic performance of ANA detection increases when using a cut-off point of 1:160, with a specificity of 86.2% and a sensitivity of 95.8% 1.
Clinical Implications
- In patients with new onset psychosis, a positive ANA test should prompt further evaluation, including clinical assessment and additional diagnostic tests, such as anti-ENA and anti-Ro autoantibodies, to determine the underlying cause of the psychosis 1.
- The EULAR/ACR 2019 classification criteria recommend ANA detection using the IFI or a solid-phase ANA screening immunoassay (SPA) with at least equivalent performance, but the choice of method and cut-off point should be guided by the clinical context and laboratory expertise 1.
- In patients with suspected autoimmune disorders, such as neuropsychiatric lupus, contrast-enhanced brain MRI may be performed for definitive characterization of a focal lesion or to evaluate for other underlying conditions 1.
From the Research
Significance of a Positive ANA Test in First-Episode Psychosis
- A positive Antinuclear Antibody (ANA) test in a patient experiencing their first episode of psychosis may indicate the presence of an underlying autoimmune condition, such as systemic lupus erythematosus (SLE) 2, 3.
- The prevalence of neuropsychiatric SLE (NPSLE) in patients with psychosis who are positive for ANAs is relatively low, ranging from 1.5% to 2% 3.
- However, the detection of ANAs can be an important screening test for NPSLE in patients presenting with first-episode psychosis, as it is a low-cost procedure and can help identify patients who may benefit from immunotherapy 2.
- Autoantibodies, including those against the N-methyl-D-aspartate (NMDA) receptor, have been identified in a small subset of patients with psychosis, and may contribute to the development of psychotic symptoms 4, 5.
- The presence of autoantibodies in patients with first-episode psychosis may have implications for treatment, as some patients may respond to immunomodulatory therapy 4, 6.
Implications for Diagnosis and Treatment
- The identification of a positive ANA test in a patient with first-episode psychosis should prompt further evaluation for underlying autoimmune conditions, including SLE and NPSLE 2, 3.
- Patients with positive ANA tests and psychotic symptoms should be referred to a rheumatologist or other specialist for further evaluation and treatment 3.
- The use of immunomodulatory therapy, such as cyclophosphamide, may be beneficial in patients with NPSLE and psychotic symptoms 2.
- Further research is needed to determine the optimal approach to screening and treatment for patients with first-episode psychosis and positive ANA tests 6.