Diagnosing solvent-induced chronic toxic encephalopathy: the effect of underperformance in neuropsychological testing.

Objective: The diagnoses of solvent-induced chronic toxic encephalopathy (CSE) can be supported by neuropsychological tests. However, since results not only reflect cognitive functioning but also the patient's effort to perform well, this study examines to what extent underperformance impacts neuropsychological outcomes in individuals referred for suspected CSE. Methods: A retrospective study of 48 suspected CSE patients having completed ten neuropsychological tests assessing different domains of cognition. Underperformance was identified using the Amsterdam Short-Term Memory Test and the Rey 15-item Memory Test (FIT). Multiple linear regression was applied to examine the effect of insufficient effort on test performance. Results: A total of 54.1% of the patients were identified as having underperformed on one or both performance validity tests. Analyses showed a significant effect of underperformance on most tests barring letter-number sequencing. Conclusions: Most of the neuropsychological tests evaluated showed significant effects of underperformance. Performance on letter-number sequencing was not affected. In case of underperformance, the results of the neuropsychological assessment should be disregarded when weighing the final multi-disciplinary diagnosis, with the exception of letter-number sequencing. Key points A total of 54.1% of patients with suspected CSE referred for neuropsychological assessment was identified as having underperformed on one or both PVTs. Underperformance has a significant effect on most neuropsychological tests with the exception of letter-number sequencing assessing attention and working memory. In case of underperformance, the results of the neuropsychological assessment should be disregarded when weighing the final multi-disciplinary diagnosis, with the exception of letter-number sequencing.