Novel learning ratio from the NAB list learning test distinguishes between clinical groups: clinical validation and sex-related differences

Clinical validation of an aggregate learning ratio from the neuropsychological assessment battery

Quantifying learning deficits provides valuable information in identifying and diagnosing mild cognitive impairment and dementia. Previous research has found that a learning ratio (LR) metric, derived from the list learning test from the Neuropsychological Assessment Battery (NAB), was able to distinguish between those with normal cognition versus memory impairment. The current study furthers the NAB LR research by validating a NAB story LR, as well as an aggregate LR. The aggregate LR was created by combining the individual list and story LRs. Participants were classified as those with normal cognition (n = 51), those with MCI (n = 39) and those with dementia (n = 35). Results revealed the story LR was able to accurately distinguish normal controls from those with mild cognitive impairment and those with dementia and offers enhanced discriminability beyond the story immediate recall score (sum of trial 1 and trial 2). Further, the aggregate LR provided superior discriminability beyond the individual list and story LRs and accounted for additional variance in diagnostic group classification. The NAB aggregate LR provides improved sensitivity in detecting declines in impaired learning, which may assist clinicians in making diagnoses earlier in a disease process, benefiting the individual through earlier interventions.

Utility of learning ratio scores from the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word List Memory Test in distinguishing patterns of cognitive decline in veterans referred for neuropsychological evaluation

Background: The Learning Ratio (LR) is a novel learning score that has shown improved utility over other learning metrics in detecting Alzheimer's disease (AD) across multiple memory tasks. However, its utility on the Consortium to Establish a Registry for Alzheimer's Disease Word List Memory Test (CERAD WLMT), a widely used list learning measure sensitive to decline in neurodegenerative disease, is unknown. The goal of the current study was to determine the utility of LR on the CERAD WLMT in differentiating between diagnostic (MiNCD vs MaNCD) and etiologic groups (VaD vs AD) in a veteran sample. Methods: Raw learning slope (RLS) and LR scores were examined in 168 veterans diagnosed with major neurocognitive disorder (MaNCD), mild neurocognitive disorder (MiNCD), or normal aging following neuropsychological evaluation. Patients with MaNCD were further classified by suspected etiology (i.e. microvascular disease vs AD). Results: Whereas RLS scores were not significantly different between MiNCD and MaNCD, LR scores were significantly different between all diagnostic groups (p's < .05). Those with AD had lower LR scores and RLS scores compared to those with VaD (p's < .05). LR classification accuracy was acceptable for MiNCD (AUC = .76), excellent for MaNCD (AUC = .86) and VaD (AUC = .81), and outstanding for AD (AUC = .91). Optimal cutoff scores for WLMT LR were derived from Youden's index. Conclusion: Results support the use of LR scores over RLS when interpreting the CERAD WLMT and highlight the clinical utility of LR in differentiating between diagnostic groups and identifying suspected etiology.