Table 1:

Linear mixed-effects models for the effect of PPT score on cognitive scores

Independent variable type	Outcome variable	B-coefficient	95% CI (low)	95% CI (high)	Adjusted p
Baseline PPT score	SDMT	0.21	0.03	0.38	0.139
	Phonemic fluency	0.19	−0.01	0.39	0.326
	Delayed recognition	0.01	0.00	0.03	0.322
	Delayed recall	−0.03	−0.09	0.03	0.640
	New dot	0.02	0.00	0.05	0.345
	Digit-span	0.03	−0.02	0.08	0.634
	Odd-man-out	−0.01	−0.06	0.04	0.696
PPT score (time-varying)	SDMT	0.39	0.25	0.53	< 0.001
	Phonemic fluency	0.14	−0.05	0.33	0.548
	Delayed recognition	0.00	−0.02	0.01	1.000
	Delayed recall	0.01	−0.04	0.07	1.000
	New dot	0.03	0.00	0.06	0.354
	Digit-span	0.00	−0.05	0.05	1.000
	Odd-man-out	0.04	0.00	0.09	0.390

Two linear-mixed effects models were constructed for each cognitive test (dependent variable). For models measuring the effect of baseline PPT (score at enrollment) on cognitive test score over time, baseline values were also used for all other adjusting covariables. For the non-baseline models, the values at each follow-up assessment were used for all covariables. Baseline cognitive test score was used to adjust all models. B-coefficients (unstandardized coefficients) and 95% confidence intervals (95% CI) correspond to the relationship between bimanual PPT score (independent variable) and the indicated neuropsychological test. P-values for baseline and longitudinal models were separately adjusted using the Holm method, using the number of tests (7) as the number of multiple comparisons. Covariables adjusted for in all models include sex, education (years), age, disease duration, UPDRS III subsections (rigidity, postural tremor, postural instability, hand movements), and Hoehn & Yahr stage.