IN THE 1990s, surgical stimulation techniques were introduced to treat patients with Parkinson disease (PD) in whom pharmacological treatment failed.
1 Although there is growing evidence of the beneficial effects of chronic bilateral subthalamic deep brain stimulation (STN-DBS) on PD motor symptoms,
2-7 its influence on neuropsychological functions has not yet been investigated thoroughly. Although STN-DBS does not produce a global frontal deterioration,
6,8 a negative effect in specific prefrontal functions (eg, phonetic verbal fluency)
8,9 and verbal and visuospatial memory
9 has been described. However, reports of performance on a prefrontal measure, the Trail-Making B Test, are contradictory. Although Trépanier et al
9 found poorer performance, Ardouin et al
8 found improvement after STN-DBS, a discrepancy that may be due to methodological differences. For instance, in the study by Trépanier et al,
9 the neuropsychological assessment was performed while patients were under the effects of levodopa, whereas in the study by Ardouin et al,
8 it was performed while some patients were receiving and others were free of levodopa.