Affiliations: Cognitive Motor Neuroscience Group, Sobell Department
of Motor Neuroscience & Movement Disorders, UCL Institute of Neurology,
London, UK | Clínica de Trastornos del Movimiento, Centro
Internacional de Restauración Neurológica, CIREN,
Cubanacán, Habana, Cuba
Note: [] Corresponding author: Marjan Jahanshahi, Sobell Department of
Motor Neuroscience and Movement Disorders, Institute of Neurology, 33 Queen
Square, London, WC1N 3BG. Tel.: +44 203 1080033; Fax: +44 207 419 1860; E-mail:
m.jahanshahi@ion.ucl.ac.uk
Abstract: Changes of cognitive function in PD have been extensively documented
and defined as a 'frontal' type executive dysfunction. One of the main
components of this executive dysfunction is the impairment of verbal fluency.
The aim of the present study was to assess semantic and phonemic fluency in a
large sample of PD patients and to investigate the effect of clinical and
sociodemographic variables on verbal fluency in this patient group. Three
hundred patients with idiopathic Parkinson's disease who were consecutive
referrals to our clinic and 50 age and education matched healthy controls
completed the phonemic and semantic verbal fluency tasks. Both phonemic and
semantic verbal fluency were significantly impaired in PD patients relative to
matched controls. Stage of illness, presence of depression, education and age
influenced verbal fluency measures. Regression analyses established that global
measures of cognitive ability (MMSE) and executive function (FAB) and side of
onset of motor symptoms predicted 36–37% of variance of phonemic or
semantic verbal fluency measures. Thus, future studies aimed at assessing
cognitive functioning in PD patients treated by deep brain stimulation (DBS)
should adequately take into account several factors (stage of illness,
depression, executive functioning) which may potentially influence performance
on verbal fluency tasks.
