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Table 4 Neuropsychological results in 30 PCB-exposed and 30 control subjects

From: Neuropsychological effects of chronic low-dose exposure to polychlorinated biphenyls (PCBs): A cross-sectional study

  Raw Values T-Scores1      
  PCB Contr. PCB Contr. Effect sizes
  Mean SD Mean SD Mean SD Mean SD F[1,56]2 p2 d1 3 d2 3  
General intelligence -0.03 4 1.09 4  
WAIS IQ 72.2 9 72.2 9 113.3 10 115.8 10 0.86 0.36 -0.25 1.09  
WAIS General knowledge 18.2 3 17.7 3 58.2 9 58.8 9 0.07 0.79   0.97  
WMS Digit span forward 9.7 2 9.2 2 60.0 10 57.7 10 0.79 0.38 0.24 0.99  
WAIS Similarities 19.7 3 19.3 3 63.0 9 62.8 9 0.01 0.94   1.38  
WAIS Picture completion 12.4 2 12.7 2 61.1 10 63.2 10 0.74 0.39 -0.23 1.15  
Visuo-motor performance -0.21 0.47  
WAIS Block design 21.9 6 22.5 6 53.6 7 55.0 7 0.63 0.43 -0.21 0.47  
Concentration, alertness and speed -0.41 0.05  
Trail making Test, part A 37.5 11 34.4 11 50.1 7 53.5 7 3.67 0.06 -0.51   
Trail making Test, part B 79.3 27 74.6 27 53.7 7 55.6 7 1.11 0.30 -0.28 0.46  
TAP Phasic alertness 0.024 0.1 0.058 0.1 45.9 12 50.8 12 2.34 0.13 -0.41 -0.38 Δ
Working memory -0.08 0.08  
WMS Visual span forward 8.5 2 8.2 2 50.7 13 50.5 13 0.00 0.95    
WMS Visual span backward 8.0 2 7.3 2 50.6 10 47.6 10 1.31 0.26 0.31   
WMS Verbal span backward 7.2 2 7.4 2 50.2 11 52.8 11 0.84 0.36 -0.25   
TAP Working memory/errors 4.9 4 6.3 4 52.35 11 505 10 2.08 0.16 0.39 0.23  
TAP Response shifting/errors 6.3 4 6.0 4 47.55 14 505 10 0.09 0.76   -0.20  
TAP Divided attention/errors 2.0 1 1.2 1 43.55 10 505 10 4.79 0.03 -0.58 -0.65 Δ
WAIS Digit symbol 53.3 11 54.0 11 56.3 9 57.1 9 0.12 0.73   0.61  
Verbal memory 0.40 -0.83  
WMS Logical memory recall 22.5 7 21.7 7 42.2 9 41.5 9 0.09 0.76   -0.85  
WMS Logical memory delay 18.9 7 16.3 6 42.8 9 39.4 9 2.24 0.14 0.40 -0.83  
AVLT Word list learning 75.8 11 70.8 11 53.8 9 49.6 9 3.08 0.08 0.47 0.29  
Visual memory 0.93 0.83  
WMS Visual memory recall 39.5 5 34.2 5 61.7 10 52.4 10 13.26 0.001 0.97 1.24  
WMS Visual memory delay 34.2 9 27.1 9 56.3 12 46.2 12 11.09 0.002 0.89 0.43  
Frontal lobe functions 0.24 0.42  
RWT Word fluency 17.2 3 16.0 3 55.3 6 53.7 6 1.19 0.28 0.29 0.69  
Design fluency 30.6 7 29.3 7 51.5 9 50.2 10 0.53 0.47    
Psychomotor speed [TAP, 78] -0.39 -0.24  
Simple reaction time (RT) 281.1 125 253.8 123 48.7 14 52.3 13 1.06 0.31 -0.27   
RT with warning stimulus 275.5 120 236.2 118 46.6 13 51.2 12 2.08 0.15 -0.39 -0.24 Δ
RT working memory task 687.7 229 556.5 226 46.2 12 53.5 12 5.91 0.02 -0.65 -0.36 Δ
RT response shifting task 869.9 275 847.3 270 48.0 12 52.3 12 2.06 0.16 -0.38   
RT divided attention task 702.5 96 665.8 94 42.8 10 46.8 10 2.56 0.12 -0.43 -0.69 Δ
  1. 1 Lower values indicate poorer performance
  2. 2 F-value for group effect adjusted for gender, nominal α
  3. 3 Effect sizes (>0.2): d 1 relative to controls, adjusted for gender; d 2 relative to the normative population; Δ: at least moderate attenuation of d1 and d2 suggesting potential reproducibility
  4. 4 Effect size median
  5. 5 Relative to controls.