Improving the management of obsessive-compulsive disorder by considering the autoimmune diathesis

To the Editor

Obsessive-compulsive disorder (OCD) has been frequently associated with systemic autoimmune diseases such as multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis or thyroid autoimmune disease. Humoral immunity seems to be strongly implicated especially in the pathophysiology of paediatric OCD, associated with streptococcal infections. The evidence of response to immunomodulatory therapies (such as plasma exchange and intravenous immunoglobulins) in children with treatment-refractory OCD is in favour of the neuroimmune hypothesis. Therefore, in a previous work, systematic studies of the immune function in adult OCD patients have been recommended, since in the clinical practice, the issue of an autoimmune diathesis in these patients is underestimated. The association between an autoimmune diathesis and a subset of OCD may have some significance in terms of reciprocal risk factors (Di Michele, 2007).

In the last decade, new studies support the neuroimmune hypothesis in OCD. Namely, a dysregulated immune response is hypothesized to result in inflammation of neuronal networks, particularly the basal ganglia nuclei.

Recently, the prevalence of anxiety disorders, especially OCD, in patients with euthyroid Hashimoto’s thyroiditis has been found to be significantly higher than in the control group. The authors claim that thyroid autoimmunity and other thyroid pathologies should be investigated in euthyroid patients with chronic and treatment-resistant complaints (Giynas Ayhan et al., 2014).

Also, it has been shown that the proportion of OCD subjects with positive anti-streptolysin (ASO) titre (>200 IU/mL) was significantly greater than in major depression patients. For a small proportion of participants, autoimmune reactions towards neuronal structures were present (anti-brain antibodies) (Maina et al., 2009). Therefore, ASO titration may be useful in the context of autoimmune pathologies, including OCD.

Overall, simple laboratory analyses (leucocytic formula, C-reactive protein, Rheuma test, ASO) suggestive of the presence of an inflammatory process, together with a complete thyroid function test (including thyroid-stimulating hormone, triiodothyronine, thyroxine, thyroglobulin, anti-thyroglobulin, anti-thyroid peroxidase, thyroid microsomal antibodies), should be carried out in OCD patients, in search for possible associations with autoimmune diseases. In case some of these are positive, aset of specific auto-antibodies (antibrain, antibasal ganglia) could be then examined. Also the measurement of pro-inflammatory cytokines (tumour necrosis factor-a, natural killer cells) levels, may be relevant for detecting neuroinflammatory processes.

This may be important not only for a correct clinical diagnosis but also for a better pharmacological treatment. This should include a specific therapy for OC symptomatology and address the possible autoimmune diathesis, correcting thyroid dysfunction or inflammatory processes.