Relative impacts of mild and major neurocognitive disorder on rate of verbal learning acquisition

Objective: The California Verbal Learning Test-second edition (CVLT-II) learning slope index may signal the presence of cognitive impairment, though the relative impacts of mild (MiND) and major (MaND) neurocognitive disorders on the rate of verbal learning acquisition remain unknown.

Methods: Latent intercept-only, linear, quadratic, and exponential models were fit to raw scores for the five CVLT-II learning trials of 197 veterans. Dummy-coded variables reflecting MiND and MaND predicted the growth factors.

Results: Quadratic growth best fit the data. MiND and MaND predicted reduced recall on each trial. MaND predicted reduced rate of learning acquisition (i.e., word gains per trial) over-and-above MiND, even after controlling for age, sex, education, race/ethnicity, and mono/bilingualism.

Conclusions: Nonlinear growth-with continuous but diminishing gains over trials-best characterized verbal learning acquisition. Reduced word recall each trial may help differentiate MiND from no neurocognitive disorder, while reduced rate of verbal learning acquisition may help differentiate MaND from MiND.