Symptoms of somatization as a rapid screening tool for mitochondrial dysfunction in depression

Aims: Somatic symptomatology is common in depression, and is often attributed to the Freudianin-spired concept of somatization. While the same somatic symptoms and depression are common in mitochondrial disease, in cases with concurrent mood symptoms the diagnosis of a mitochondrial disorder and related therapy are typically delayed for many years. A short screening tool that can identify patients with depression at high risk for having underlying mitochondrial dysfunction is presented. Methods: Six items of the Karolinska Scales of Personality (KSP) were found to differentiate among 21 chronically-depressed Swedish subjects with low versus normal muscle ATP production rates. A screening tool consisting of the six KSP questions was validated in the relatives of American genetics clinic patients, including in 24 matrilineal relatives in families with maternally inherited mitochondrial disease and in 30 control relatives. Results: Among the depressed Swedish patients, the screening tool was positive in 13/14 with low and 1/7 with normal mitochondrial function (P = 0.0003). Applied to the American relatives of patients, the screening tool was positive in 13/24 matrilineal relatives and in 1/30 control relatives (P = 2 x 10(-5)). Conclusion: Our preliminary data suggest that a small number of specific somatic-related questions can be constructed into a valid screening tool for cases at high risk for having a component of energy metabolism in their pathogenesis.