IQ and WAIS scores in ADHD are in the average range, with slightly lower WMI
Group means for overall IQ, verbal comprehension, reasoning, working memory, and processing speed in ADHD are all within the average range. The most consistent difference is a small reduction in Working Memory Index. In a meta-analysis of WAIS-IV and WISC-V, mean WMI was 95.2 in adults and 93.7 in children, around four to six points below the normative mean of 100.
In the same analysis, adults with ADHD had mean scores of 98.4 for FSIQ, 102.1 for verbal comprehension, and 99.7 for perceptual reasoning. IQ in ADHD spans the full range and is compatible with high verbal comprehension or reasoning.
The modest WMI difference is a group average, not a fixed pattern shared by every person. ADHD and working memory explains how retention and manipulation relate to everyday difficulty.
PSI is not uniformly low, while performance tends to be more variable
Mean Processing Speed Index was 96.2 in adults with ADHD and 92.3 in children, both within the average range. PSI was not a clear within-person weakness against reasoning in adults, and no significant difference from fluid reasoning was found in children. ADHD does not imply a low PSI.
What is more characteristic is variability in speed from trial to trial rather than being consistently slow. A meta-analysis of reaction-time variability found greater trial-to-trial variability in ADHD; once that variability was taken into account, the groups no longer differed in average reaction time.
Reaction-time variability and WAIS PSI are different measurements. A person can have an average PSI yet alternate between periods of rapid progress and periods of stopping in work or learning. ADHD and processing speed explains how to separate a low PSI from time lost to stopping, resuming, and rework.
Average WAIS scores can coexist with inconsistent everyday execution
During WAIS, an examiner presents one task at a time and controls its start and end. Everyday life requires the person to choose a goal, start, return after interruptions, and manage progress through a deadline.
WMI and PSI can therefore be average even when attention drifts while information is being taken in, starting takes time, the current position is lost after interruption, pace fluctuates, or completion by the deadline remains difficult. Average WAIS scores and stable everyday execution are not the same thing.
Cognitive differences and developmental conditions explains why a broadly average profile does not rule out substantial day-to-day difficulty.
Read ADHD WAIS results by connecting scores with the conditions of difficulty
WAIS results can help identify where execution becomes unstable: retention, starting, resuming, or output.
| Result | Conditions to examine |
|---|---|
| WMI is relatively low within the profile | Several spoken instructions, retaining intermediate results, resuming after interruption |
| PSI is relatively low within the profile | Visual search, transcription and matching, handwriting, time limits |
| WMI and PSI are both average | Starting, prioritizing, variation in pace, interruptions, completion by a deadline |
First locate the score relative to the same-age population, then compare it with the person's other abilities. Finally, check where the same demand occurs in everyday life. How to read WAIS results explains index differences and subtest patterns.
This connects the test result with the specific stage where support or an environmental adjustment is needed instead of ending with a group average or score difference.