Table 4.

Associations between neuropsychological test scores and surface-years of exposure to amalgam restorations [adjusted coefficient ± SE (n)].

Test score	Surface-years of amalgam	p-Valuea
WISC-III
Factor
Verbal Comprehension	0.01 ± 0.02 (434)b	0.48
Perceptual Organization	0.00 ± 0.02 (433)	0.94
Freedom from Distractibility	0.02 ± 0.02 (433)	0.50
Processing Speed	0.03 ± 0.03 (431)	0.28
Subtest
Verbal
Information	−0.00 ± 0.01 (434)	0.74
Similarities	0.00 ± 0.01 (434)	0.83
Vocabulary	0.01 ± 0.00 (434)	0.19
Comprehension	0.01 ± 0.01 (434)	0.33
Digit Span	0.01 ± 0.01 (433)	0.26
Performance
Picture Completion	0.01 ± 0.01 (434)	0.41
Coding	0.00 ± 0.01 (433)	0.47
Picture Arrangement	−0.00 ± 0.01 (433)	0.46
Block Design	0.00 ± 0.01 (434)	0.58
Object Assembly	−0.00 ± 0.01 (433)	0.66
Symbol Search	0.01 ± 0.01 (431)	0.29
Mazes	0.01 ± 0.01 (433)	0.35
WIAT
Composite
Reading	0.03 ± 0.02 (430)	0.20
Mathematics	0.03 ± 0.03 (421)	0.33
Scale
Basic Reading	0.03 ± 0.02 (433)	0.16
Reading Comprehension	0.02 ± 0.02 (430)	0.41
Numerical Operations	0.03 ± 0.03 (421)	0.29
Math Reasoning	0.01 ± 0.02 (433)	0.75
Spelling	0.03 ± 0.02 (432)	0.21
Listening Comprehension	−0.03 ± 0.02 (415)	0.19
WRAML
Index
Verbal Memory	0.01 ± 0.03 (406)	0.73
Visual Memory	0.05 ± 0.03 (408)	0.10
Learning	0.02 ± 0.03 (407)	0.64
Scale
Picture Memory	0.02 ± 0.01 (408)	0.008
Design Memory	−0.01 ± 0.01 (408)	0.48
Story Memory	−0.00 ± 0.01 (407)	0.57
Verbal Learning	0.00 ± 0.01 (407)	0.99
Finger Windows	0.01 ± 0.01 (408)	0.14
Sound Symbol	0.01 ± 0.01 (407)	0.26
Sentence Memory	−0.00 ± 0.01 (408)	0.52
Visual Learning	−0.00 ± 0.01 (407)	0.67
Number–Letter Memory	0.01 ± 0.01 (407)	0.01
WRAVMA
Drawing	−0.02 ± 0.04 (406)	0.56
Matching	−0.04 ± 0.03 (406)	0.27
Pegboard	0.03 ± 0.04 (406)	0.45
Trail-Making Test
Part A: time to complete	0.02 ± 0.01 (395)	0.22
Part A: no. of errors	−0.00 ± 0.00 (395)	0.26
Part B: time to complete	0.06 ± 0.04 (387)	0.15
Part B: no. of errors	0.00 ± 0.00 (387)	0.38
Finger Tapping
Right hand (mean of 5 trials)	0.01 ± 0.01 (402)	0.53
Left hand (mean of 5 trials)	0.01 ± 0.01 (402)	0.42
Verbal Cancellation
Ordered trial: no. of errors	0.00 ± 0.01 (367)	0.88
Unordered trial: no. of errors	0.00 ± 0.01 (367)	0.77
Verbal Fluency
Category fluency (sum of 4 trials)	0.00 ± 0.02 (404)	0.84
Letter fluency (sum of 3 trials)	0.04 ± 0.02 (404)	0.05
Reaction Time
Mean response time (msec)	−0.00 ± 0.00 (356)	0.62
Response time SD	0.00 ± 0.00 (356)	0.46
Stroop Color–Word Interference Test
Color	0.01 ± 0.03 (323)	0.70
Word	0.00 ± 0.03 (322)	0.97
Color–Word	−0.00 ± 0.02 (323)	0.87
Wisconsin Card Sorting Test
No. of categories achieved	−0.00 ± 0.00 (387)	0.50
No. of trials to first category	−0.00 ± 0.01 (387)	0.92
Total errorsc	−0.04 ± 0.04 (383)	0.24
Total perseverative errorsc	−0.05 ± 0.04 (383)	0.20
Percent conceptual level responses	−0.04 ± 0.04 (383)	0.29

^aAdjusted for baseline score, randomization stratum, baseline age, sex, baseline family socioeconomic status, baseline hair mercury concentration, and baseline blood lead concentration.

^bCoefficient represents the change in test score for each unit increase in surface-years of amalgam.

^cStandard score.