Neurasthenia in the 1980s: chronic mononucleosis, chronic fatigue syndrome, and anxiety and depressive disorders.

In the 1980s, patients suffering from unexplained fatigue and what seemed like a prolonged attack of acute mononucleosis were given the diagnosis of chronic mononucleosis or chronic infection with the Epstein-Barr virus. Although the diagnosis has great appeal, the Epstein-Barr virus does not cause the syndrome (CFS) of chronic fatigue, which has been renamed and redefined chronic fatigue syndrome to remove the inference that the virus is its cause. From a historical perspective, both syndromes represent the 1980s equivalent of neurasthenia, a disease of fatigue that influenced the development of psychiatric nosology. Because patients with depression and anxiety also have chronic fatigue and because most patients with CFS have an affective disorder, the assessment of organic causes of this syndrome requires careful psychiatric diagnosis and treatment. Defining chronic fatigue syndrome as a medical disorder may deprive patients of competent treatment of their affective disorder.