Personality disorders and somatization in functional and organic movement disorders

Psychiatric disturbances and somatizations are both criteria which support the diagnosis of functional movement disorders. It is unclear, however, whether these factors are helpful in differentiating functional and organic movement disorders. To address this issue, the Structured Clinical Interview for DSM-IV Axis I and II psychiatric disorders, the State-Trait Anxiety Inventory, the Beck Depression Inventory and the somatization section of the Dissociative Disorders Interview Schedule were administered to 31 functional movement disorder patients diagnosed, according to Fahn and Williams criteria and 31 sex- and age-matched control outpatients, with adult onset dystonia. Axis I psychiatric diagnoses were similarly frequent in patients with functional and organic movement disorders. There was a trend to a greater frequency of personality disorders overall; when looking at individual personality disorders, there was no significant between-group difference. Depression and anxiety scores and mean number of somatizations per patient were also greater in the functional group. The number of somatic complaints significantly correlated with depression and anxiety scores. However, the presence of these disturbances in a proportion of patients with organic dystonia indicates that personality disorders and somatizations do not aid in distinguishing functional and organic movement disorders.