ABSTRACT
Cognitive slowing, or bradyphrenia, is a hallmark symptom of subcortical disorders (SCDs), which otherwise are clinically characterized by their pathognomonic motor symptoms and associated neurobehavioral alterations. Although bradyphrenia commonly is defined as a slowing of cognitive processes (Rogers, 1986), more broadly it has been described as "slowness of thought, impaired attention and motivation, lack of spontaneity, inflexibility and forgetfulness" (Lees, 1994, p. 823). SCDs include Parkinson's disease (PO), Huntington's disease (HD), progressive supranuclear palsy (PSP), Wilson's disease, multiple system atrophy (MSA), Tourette's syndrome, spinocerebellar ataxia (SCA), Shy-Drager syndrome, and olivopontocerebellar atrophy (Cummings, 1986; Rinne, 2003). In addition to bradyphrenia, cognitive impairments in SCDs include problems with attention, verbal fluency, executive functions, recall, visuospatial ability, visual learning memory, and acquisition of motor skills (Albert, Feldman, & Willis, 1974; Cummings, 1990; Dubois, Defontaines, Deweer, Malapani, & Pillon, 1995). In contrast to many cortical disorders, in SCDs there generally is an absence of "instrumental" deficits of apraxia, aphasia, and agnosia (Cummings, 1986; Pillon, Ertle, Deweer, Sarazin, Agid, & Dubois, 1996). Since cognitive slowing also is evident in many cortical disorders (e.g., stroke, traumatic brain injury and Alzheimer's disease (AD», it is unclear to what extent bradyphrenia as a presenting symptom has utility for distinguishing subcortical from cortical disorders.
