Using Testing Data in the Diagnosis of ADHD

The diagnosis in children of Attention-Deficit/Hyperactivity Disorder is made by careful attention to the individual’s (1) medical and developmental history, and (2) the individual’s presentation in a variety of settings (usually home and school). Our testing database has 306 cases where the primary diagnosis was ADHD. We analyzed our data to see if a continuous performance test (the Conners’ Continuous Performance Test) provided information that would be useful to consider for the diagnosis of ADHD.

The computerized scoring of the Conners’ Continuous Performance Test provides nine measures, and in our data, we found three of the nine measures to be significant. The Conners’ Continuous Performance Test is a computerized test that is 14 minutes long (7 minutes in the early childhood version), and it is a “go/no go” task. That is, the individual responds to target letters (or pictures) except for one (the letter, X, in the standard version).

The CPT measures are reported as T-scores, and we have converted these scores to percentiles because they are more familiar to people. By this convention, a score at the 50th percentile would be average. The two measures of response consistency were elevated in our data:

  • Reaction time standard error – 72nd percentile.
  • Variability of standard errors – 70th percentile.

The individual’s sensitivity to the speed of presentation of the letters was also elevated in the ADHD group. That is, if the letters were presented at one per second, the individual tended to respond quickly; if the letters came at one every 4 seconds, the individual tended to respond slowly (Hit reaction time ISI change). The average for this measure in our data was 65th percentile.

Consistent with our understanding of the effects of ADHD on performance, our CPT data suggests that response consistency and sensitivity to change can be useful measures from testing.

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