title: [Impact of the cognitive impairment on the quality of life in patients with Parkinson's disease].
abstract: OBJECTIVE
  To review aspects related to the impact caused by the cognitive deterioration on the health-related quality of life (HRQL) of patients with Parkinson's disease.
  
  
  METHODS
  Some definitions of the construct HRQL and the classification of the HRQL measures are displayed. In addition, those factors associated to cognitive impairment and dementia which have potential to decrease the patients' HRQL are reviewed. A point of special interest in this field is linked to the consequences of the cognitive impairment on the HRQL measurement, because this construct is better understood as self-assessment based on a subjective and self-controlled judgment. Such disturbances as the loss of memory and problems of language, may challenge the self-assessment and turn its content unreliable. An effect of this problem is exclusion of patients with cognitive impairment from studies that contain the HRQL as an end-point and, therefore, scarce information about this issue in cognitively impaired Parkinson's disease patients is available. Furthermore, usual valid HRQL measures may be useless in patients with advanced cognitive deterioration or dementia. Specific instruments to be applied in this setting have been, therefore, created to solve this situation.
  
  
  CONCLUSIONS
  HRQL is severely decreased by cognitive impairment. Measurement of the impact in this context may be problematic and little empiric knowledge about this impact exists.
authors.affiliation: Sección de Neuroepidemiologia, Centro Nacional de Epidemiología. Instituto de Salud Carlos III, 28029 Madrid, Spain. pmartinez@isciii.es
authors.forename: P
authors.initials: P
authors.lastname: Martínez-Martín
mesh_terms: D003071:Cognition; D006801:Humans; D010300:Parkinson Disease / Q000503:physiopathology / Q000523:psychology; D011788:Quality of Life; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires