Several factors have been suggested as underlying the pathophysiology of major depression and schizophrenia, including alterations in autoantibodies. However, while some antibodies have been studied in relation to these conditions, several have not been examined.

Christoph Laske and colleagues from the University of T¨¹bingen therefore determined serum levels of antinuclear (ANA), smooth muscle (SMA), anti-endothelial (AEA), anti-sarcolemma (ASA), thyroid gland (TGA), and parietal cell (PCA) antibodies in 25 patients with unipolar major depression, 34 with schizophrenia, and 50 healthy controls.

The results, published in the journal Psychiatry Research, show that unipolar major depression patients were significantly more likely to have increased ANA, TGA, and PCA reactivity than controls, at 8% versus 0%, 8% versus 2%, and 40% versus 2%, respectively.

In addition, the team found that schizophrenia patients were significantly more likely to have increased ANA and SMA reactivity than controls, at 5.9% versus 0.0%, and 17.6% versus 6.0%, respectively.

Comparing the two patient groups, PCA levels were found to be significantly increased in major depression, while SMA levels were significantly increased in schizophrenia. There were no differences among the three groups in terms of AEA and ASA.

"In conclusion, the findings of elevated autoantibodies in psychiatric disorders like major depression and schizophrenia points to the existence of a subgroup of patients with a co-existing autoimmune or inflammatory process," the researchers write.

They add: "That raises the question of whether this subgroup of antibody-positive psychiatric patients should be treated with immunosuppressants similar to other autoimmune diseases, especially in cases of non-response to the usual antidepressants or neuroleptics."