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. Author manuscript; available in PMC: 2021 Nov 25.
Published in final edited form as: Drug Alcohol Depend. 2020 May 25;213:108063. doi: 10.1016/j.drugalcdep.2020.108063

Table 2.

Neuropsychological Performance of participants (Mean ± S.E.) and p-values from One-way ANCOVA

ND (N=56) Primarily-K Users (K, N=60) K+PolyS Users (K+PS, N=64) 1-way ANCOVA p-value
 post hoc p-value (adjusted)
Age Sex Education Group ND v. K ND v. K+PS K v. K+PS
Working memory
Digit span forward 15.5 ± 0.2 15.5 ± 0.2 15.2 ± 0.2 0.191 0.990 0.597 0.321
Digit span backward 9.8 ± 0.5 8.9 ± 0.4 8.5 ± 0.4 0.069 0.459 0.047 0.217
Arithmetic 16.2 ± 0.6 13.5 ± 0.5 13.2 ± 0.4 0.748 0.013 <0.001 <0.001a 0.002 <0.001 0.624
Verbal Memory
LM retentionc 87.8 ± 3.7 71.2 ± 3.0 81.4 ± 2.8 0.075 0.293 0.493 0.003a 0.007 0.621 0.022
LM recognition 25.2 ± 0.7 21.2 ± 0.5 22.2 ± 0.5 0.009 0.012 0.435 <0.001a <0.001 0.004 0.414
WL retentionc 86.4 ± 4.1 77 ± 3.7 84.2 ± 3.6 0.014 0.830 0.617 0.053
Visual Memory
RCF retentionc 1 ± 0 1.1 ± 0 1. ± 0 0.858 0.398 0.699 0.328
Learning
LM immediate recall 40.7 ± 2.4 27.2 ± 2.2 33.3 ± 2.1 0.019 0.154 0.068 <0.001a <0.001 0.002 0.210
WL first recall 5.8 ± 0.3 5.1 ± 0.2 5.3 ± 0.2 0.005 0.442 0.263 0.246
RCF immediate recall 25.3 ± 1.2 21.2 ± 1.0 19.0 ± 0.9 0.857 0.231 0.841 0.001a,b 0.070 0.001 0.277
Executive Function
Verbal Fluencyd 47.9 ± 1.6 41.2 ± 1.5 46.8 ± 1.4 0.414 0.157 0.039 0.121
Stroop interference 8.2 ± 1.1 10.7 ± 0.9 10.7 ± 0.8 0.327 0.387 0.768 0.246
WCST total errors 20.5 ± 2.9 24.8 ± 2.4 25 ± 2.2 0.012 0.832 0.104 0.517
RCF copy 33.6 ± 0.5 33.9 ± 0.4 32.6 ± 0.4 0.757 0.635 0.049 0.016
Speed of Information Processing
Stroop color reading 13.4 ± 0.5 12.6 ± 0.4 12.4 ± 0.4 0.803 0.076 0.003 0.407
Digit symbol coding 89.2 ± 2.5 88.1 ± 2.1 85.0 ± 1.9 0.009 0.019 0.004 0.325
Language
MBNT 15.1 ± 0.2 14.5 ± 0.1 14.4 ± 0.1 0.363 0.052 0.708 0.056
a

Tukey’s Test of post hoc comparisons were performed only for groups that have p values remain significant after Holm-Bonferroni correction.

b

p-value for RCF immediate recall was 0.005 after covariated for RCF copy.

c

LM retention: LM delayed recall/LM immediate recall; WL retention: WL delayed recall/WL 5th immediate recall; RCF retention: RCF delay recall/RCF copy.

d

Sex-by-group interaction showed a trend for significance for Verbal Fluency, p=0.030 (not significant after Holms-Bonferroni correction).

Abbreviations: LM: Wechsler Adult Intelligence Test-III (WAIS-III) Logical Memory; RCF: Rey-Osterrieth Complex Figure test; WL: WMS-III Words Learning; WCST: Wisconsin Card Sorting Test; MBNT: Modified Boston Naming test.