Validation of the Neuronorma battery for neuropsychological assessment in multiple sclerosis

BACKGROUND: Cognitive dysfunction is prevalent among patients with multiple sclerosis (MS). In recent years, several (generally brief) neuropsychological batteries have been proposed for cognitive assessment. There is a need for comprehensive batteries providing complete cognitive assessment of patients with MS. The Neuronorma battery includes several standardised neuropsychological tests examining the main cognitive domains, and is available in several countries. The aim of this study was to validate the battery for cognitive assessment in a sample of patients with MS and healthy controls, and to find the most appropriate criteria for defining cognitive impairment using this battery. METHODS: Five hundred and sixty participants (280 with MS and 280 controls matched for age, sex, and years of education) were included. Inter-group differences were calculated using the Mann-Whitney U test and effect sizes with Cohen's d. Several criteria for definition of cognitive impairment were evaluated, according to different cut-off points, and the number of tests and cognitive domains impaired. Receiver operating characteristic curves with 95% confidence intervals were estimated and they were compared using the DeLong method. RESULTS: Patients with MS showed poorer performance in almost all cognitive tests, with large effect sizes for the Symbol Digit Modalities Test and Judgement of Line Orientation, and moderate effects for Digit Span Backward, the Corsi test, Trail Making Test, Free and Cued Selective Reminding Test, Rey-Osterrieth Complex Figure (recall), verbal fluency (P words), and the Stroop Color-Word Interference Test. The area under the curve was superior for classification by cognitive domain than for the mean scaled score of the tests or the number of tests showing impairment according to different cut-off points for the adjusted scaled scores. CONCLUSIONS: Our study validates the Neuronorma battery for cognitive assessment of patients with MS. The battery is currently available in several countries with reliable normative data, and may be useful in both the clinical and the research settings when comprehensive neuropsychological examination is warranted.