Neuropsychological performance and urinary phenylethylamine in Tourette's syndrome.

Patients with Tourette's syndrome (TS) were grouped on the basis of levels of urinary phenylethylamine (PEA). These groups of TS patients were compared on an extensive battery of neuropsychological measures converted to age-corrected T scores based on published normative data. Patients with PEA levels below that of normal controls performed significantly worse than TS patients with normal PEA levels. The data were interpreted to suggest that abnormalities in PEA may contribute to neuropsychological deficits. Furthermore, these data may provide further support for an etiological subgroup of TS patients characterized by an abnormality in PEA metabolism. These data are discussed in regard to directions for further investigation.