Influence of Antipsychotic and Anticholinergic Loads on Cognitive Functions in Patients with Schizophrenia

Table 3

(a) Component matrix of principal component analysis for VLMT parameters (1-factor solution). (b) Pattern matrix of main principal component analysis for cognitive domains. (4-factor solution). (c) Component intercorrelation matrix of cognitive domains. (d) Sample deviation of available cognitive variables in relation to expected values of a control population (percentile ranks and standard deviation).

(a)

Test parameter	Component loadings (VM)
VLMT (immediate recall)	.797
VLMT (interference list recall)	.805
VLMT (delayed recall)	.871
VLMT (sum lists 1 to 5)	.938
VLMT (delayed recall 2)	.893

VM: declarative verbal memory; VLMT: verbal learning and memory test.

(b)

Variable	Component loadings
	CVT	IPS	EF	ATT
RWT (formal lexical)	.751	−.023	−.095	−.011
RWT (semantic)	.562	−.166	−.172	−.253
WMS (text reproduction immediate)	.922	.048	.158	−.037
WMS (text reproduction delayed)	.904	−.015	.155	−.015
WMS (digit span forward)	.406	.020	−.531	.176
WMS (digit span backward)	.450	−.200	−.328	.269
TAP (divided attention IPS auditory)	.177	.867	−.320	.022
TAP (divided attention IPS visual)	−.163	.699	−.078	−.114
TAP (shifted reaction IPS)	−.109	.676	.106	.189
Trails A (time until completion)	−.232	.465	.313	−.040
Trails B (time until completion)	−.347	.362	.400	−.202
d2 (summation number)	.216	−.585	.034	.109
d2 (error percentage)	−.155	.027	.044	.911
WIE (number-symbol test)	−.167	−.660	−.480	−.067
TAP (shifted error reaction amount)	.138	−.148	.890	.100

Note: higher IPS and EF factor scores indicate lower performance because error amount and time parameters served as variables in the PCA (which becomes clear by examining the loading pattern of these components).

(c)

Component	CVT	IPS	EF	ATT
CVT	1
IPS	−.360	1
EF	−.263	.179	1
ATT	.091	−.042	−.018	1

CVT: complex verbal tasks; IPS: information processing speed; EF: executive functioning; ATT: attention; RWT: Regensburg Word Fluency Test; WMS: Wechsler Memory Scale; TAP: Test of Attentional Performance; TMT: Trail Making Test; d2: d2 Test of Attention; WIE: Wechsler intelligence test for adults; VLMT results were excluded and formed a separate domain (VM); see Table 3(a). Solution converged in 12 iterations.

(d)

Variable		Mean PR	SD
VLMT sum scores	115	46,87	32,64
RWT (formal lexical)	109	31,71	27,06
RWT (semantic)	110	28,84	26,54
WMS (text reproduction immediate)	101	34,83	31,35
WMS (text reproduction delayed)	99	33,30	31,37
WMS (digit span forward)	100	45,69	29,43
WMS (digit span backward)	96	43,18	31,17
TAP (divided attention IPS auditory)	113	22,24	22,82
TAP (divided attention IPS visual)	23	35,48	25,37
TAP (shifted reaction IPS)	92	23,38	23,53
Trails A (time until completion)	116	44,81	28,74
Trails B (time until completion)	113	45,94	28,32
d2 (summation number)	101	27,64	28,53
d2 (error percentage)	101	42,98	29,64
WIE (number-symbol test)	61	33,04	24,98
TAP (shifted error reaction amount)	92	49,52	29,37

Note: the expected normal value for control population is a percentile rank (PR) of 50. Values below 50 are considered worse performance than expected for controls, pointing to cognitive impairment.