Effect of processing speed and memory performance on classification accuracy of the dot counting test in a mixed neuropsychiatric sample

ABSTRACT

Objective

This study examined the impact of impairment in two specific cognitive abilities, processing speed and memory, on Dot Counting Test (DCT) classification accuracy by evaluating performance validity classification accuracy across cognitively unimpaired, single-domain impairment, and multidomain impairment subgroups within a mixed clinical sample.

Method

Cross-sectional data were analyzed from 348 adult outpatients classified as valid (n = 284) or invalid (n = 64) based on four independent criterion performance validity tests (PVTs). Unimpaired (n = 164), single-domain processing speed impairment (n = 24), single-domain memory impairment (n = 53), and multidomain processing speed and memory impairment (n = 43) clinical subgroups were established among the valid group. Both the traditional DCT E-score and unrounded E-score were examined.

Results

Overall, the DCT demonstrated acceptable to excellent classification accuracy across the unimpaired (area under the curve [AUC] traditional E-score=.855; unrounded E-score=.855) and single-domain impairment groups (traditional E-score AUCs = .690–.754; unrounded E-score AUCs = .692–747). However, it did not reliably discriminate the multidomain processing speed and memory impairment group from the invalid performers (traditional and unrounded E-scores AUC = .557).

Conclusions

Findings support the DCT as a non-memory-based freestanding PVT for use with single-domain cognitive impairment, with traditional E-score ≥17 (unrounded E-score ≥16.95) recommended for those with memory impairment and traditional E-score ≥19 (unrounded ≥18.08) with processing speed impairment. Moreover, results replicated previously established optimal cutoffs for unimpaired groups using both the traditional (≥14) and unrounded (≥13.84) E-scores. However, the DCT did not reliably discriminate between invalid performance and multidomain cognitive impairment, indicating caution is warranted when using the DCT with patients suspected of greater cognitive impairment.

KEYWORDS:

• Dot counting test
• performance validity
• psychometrics
• Neuropsychology
• cognitive impairment

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.