Table 5.

Mean Z Scores and Between-Group Differences for Cannabis Using and Nonusing FEP Groups

	N	FEP + CANN	N	FEP − CANN	p	ES
General Intelligence
Current IQ	54	−1.65 (1.40)*	20	−2.39 (0.96)*	.07	0.40
Premorbid IQ	41	−0.50 (1.14)	16	−0.57 (1.24)	.83	0.06
Verbal Memory
RAVLT—total	40	−0.73 (0.88)*	19	−1.05 (1.17)*	.21	0.33
RAVLT—recall	40	−0.65 (0.96)*	19	−1.09 (1.24)*	.15	0.44
Logical Memory	41	−1.33 (0.85)*	16	−1.59 (0.80)*	.21	0.30
Visual Memory
Visual PA—total errors	47	−0.17 (0.99)	23	−0.59 (1.08)*	.10	0.50
Visual Reproduction	35	−0.19 (0.70)	19	−0.71 (1.17)*	.05	0.60
Spatial Recognition	49	−0.39 (1.01)	23	−0.83 (1.39)*	.18	0.39
Pattern Recognition	49	−1.04 (1.20)*	23	−1.65 (1.50)*	.09	0.47
Processing Speed
Trails A	39	−1.54 (1.58)*	19	−1.98 (3.24)*	.48	0.19
Digit Symbol Coding	44	−1.83 (1.61)*	17	−1.90 (1.60)*	.67	0.04
Working Memory
SWM-errors	49	−0.94 (1.13)*	22	−1.80 (1.30)*	.01	0.74
SWM-strategy	49	−0.48 (0.91)	22	−0.88 (0.86)*	0.12	0.44
Spatial Span	49	−0.58 (0.91)	22	−1.01 (1.02)*	0.09	0.44
Executive Functioning
Block Design	36	−0.92 (1.23)*	18	−1.19 (1.65)*	0.62	0.22
ToL minimum solution	24	−0.19 (0.93)	12	−1.15 (1.37)*	0.03	0.90

Note: Corrected for age and gender differences; ES, effect size (Cohen’s d; unadjusted values); Asterisks reflect that these measures are significantly different to healthy controls. “p” represents the P values for comparisons between the FEP + CANN and FEP − CANN groups. Values in parentheses represent the SD of z scores. SWM, Spatial Working Memory; ToL, Tower of London. Additional abbreviations are explained in the footnote to table 1. Bold values indicate comparisons that were significantly different between the FEP + CANN and the FEP − CANN groups.