title: The Four Square Step Test in individuals with Parkinson's disease: association with executive function and comparison with older adults.
abstract: BACKGROUND
  In Parkinson's disease (PD), motor and cognitive impairments interact to affect functional performance adversely. A valid mobility test, the Four Square Step Test (FSST) involves multidirectional stepping over obstacles. FSST performance may also be associated with cognitive performance.
  
  
  OBJECTIVE
  This study determined the feasibility and reliability of an obstacle-based FSST in older individuals with versus without PD, and evaluated the association of PD performance of FSST with tests of cognition.
  
  
  METHODS
  Thirty-one individuals with mild-moderate PD, evaluated while ON medications, completed the obstacle-based FSST, other mobility and cognitive measures. FSST performance was compared between a PD participant sub-set (n = 24) and 24 age-matched older adults. Data were analyzed with independent t-tests, correlations, and linear regression.
  
  
  RESULTS
  Obstacle-based FSST was feasible and reliable within sessions in those with PD. Median best FSST time among individuals with PD was 11.72 s (9.99, 13.98) and FSST had concurrent validity with tests of mobility, and cognitive dual-tasking. Among cognitive tests, Trails Making Test B, which evaluates executive function, emerged as a sole contributor (49%) of variance. FSST performance did not differ between those with PD and older adults.
  
  
  CONCLUSIONS
  The obstacle-based FSST is feasible and reliable in those with PD. The relationship between cognitive status and performance on the FSST did not appear to be strongly disease-stage dependent. Using FSST in the clinic may help assess the health status of a motor-cognitive interaction in individuals with PD.
authors.affiliation: Emory University School of Medicine, Atlanta, GA, USA Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: McKee
authors.affiliation: Atlanta Veterans Affairs Rehabilitation R&D Center of Excellence for Visual and Neurocognitive Rehabilitation, Atlanta, GA, USA Department of Medicine, Division of General Medicine and Geriatrics, Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: Madeleine E
authors.initials: ME
authors.lastname: Hackney
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control; D000368:Aged; D000369:Aged, 80 and over / Q000502:physiology*; D003072:Cognition Disorders / Q000150:complications*; D056344:Executive Function; D005080:Exercise Test; D005240:Feasibility Studies; D005260:Female; D005684:Gait / Q000502:physiology; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology* / Q000534:rehabilitation; D006801:Humans; D008297:Male; D051346:Mobility Limitation; D010300:Parkinson Disease / Q000150:complications* / Q000503:physiopathology* / Q000534:rehabilitation; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013647:Task Performance and Analysis
keywords: Parkinson's disease; accidental falls; cognition; mobility limitation