More than just a movement disorder Why cognitive training is needed in Parkinson disease

Parkinson disease (PD) is a movement disorder with cardinal motor symptoms of resting tremor, bradykinesia, freezing of gait, and rigidity.(1) Most PD treatments aim to manage motor symptoms through pharmacologic and surgical interventions such as deep brain stimulation. Although these treatments can improve or slow decline in motor symptoms, they can also have adverse side effects, such as debilitating motor fluctuations, and costs are an estimated $25 billion per year in the United States alone.(2,3) In addition, nonmotor symptoms, including cognitive impairments, can be as troublesome as motor symptoms, but are not responsive to current PD treatments.(4) Results from an extensive review by Seppi et al.(4) show a lack of evidence for the effectiveness of pharmacologic treatments for cognitive decline in PD, with the exception of rivastigmine for the treatment of dementia. Cognitive difficulties in domains such as speed of processing, memory, and visuospatial and attentional executive functioning are common in PD, may appear before motor symptom onset, and can affect approximately 25% of patients at disease onset.(5) Even subtle cognitive decline can negatively affect quality of life. Furthermore, those experiencing cognitive difficulties early in disease progression are at higher risk for cognitive decline, with 80% developing dementia.(6) Therefore, there is a great need to explore nonpharmacologic, noninvasive interventions that are effective in treating cognitive symptoms in order to help patients with PD maintain daily functioning, independence and quality of life.