Cognitive Profiles in Parkinson’s Disease and Their Relation to Dementia: A Data-Driven Approach

Table 3

Results of the exploratory factor analysis and the consistency analysis on the neuropsychological test results of all 121 patients indicating a six-factor model of cognition in PD.

Factor interpretation	Factor 1	Factor 2	Factor 3	Factor 4	Factor 5	Factor 6
	frontal lobe; function	word-list memory; and recall	attention	logical memory	praxis and visual perception	fluency and naming ability
Tower of London	0.62
Trail Making Test, part B	0.64
NAI: digit span	0.65
NAI: figure test	0.69
Berlin Apraxia Test (raw score)	0.66
CERAD: word-list memory		0.77
CERAD: word-list recall		0.84
CERAD: word-list recognition		0.71
CERAD: word-list intrusion		0.77
TAP: phasic alertness			−0.80
TAP: Go-Nogo, median RT			0.70
WMS-R: logical memory I				0.88
WMS-R: logical memory II				0.87
CERAD: praxis					0.83
CERAD: praxis delay					0.83
VOSP: object decision					0.62
CERAD: verbal fluency						0.84
CERAD: Boston naming test						0.77
Trail Making Test, part A						0.66
Variance explained (%)	33.51	8.15	6.78	5.90	5.70	5.19
Cronbach’s alpha coefficient	0.67	0.78	−0.85	0.86	0.70	0.70

Analyses are based on standard norms (i.e percentile rank scores, PR: indicating the patient’s relative position in the norm group with a range between 0 and 100) of healthy German control subjects as published in the manuals; data are corrected either for age (NAI, WMS-R, VOSP) or for age and education (CERAD, TAP, TMT, TL-D). Only for the BAXT raw data were used; CERAD: Consortium to Establish a Registry For Alzheimer's Disease, German version; WMS-R: Wechsler Memory Scale-Revised; NAI: Nuernberger Alters Inventory; VOSP: Visual Object and Space Perception battery; TAP: Test of Attentional Performance; RT: Reaction Time.