Results of a study published in JAMA Neurology demonstrate that patients with posterior cortical atrophy (PCA) are more likely to have nonlanguage mathematical and visuospatial learning disabilities (LDs) compared with patients with logopenic variant primary progressive aphasia (lvPPA) and amnestic Alzheimer disease (AD).
Investigators reviewed a total of 279 medical records, which included patients with PCA (n=95), lvPPA (n=84), and amnestic AD who were matched for age, sex, and disease severity (n=100). Investigators compared patients with PCA who did and did not have LDs for cognitive and neuroimaging features. Specifically, investigators sought to determine the prevalence of total LD history as well as the prevalence of mathematical or visuospatial and language LD history.
At baseline, the only significant differences between the 2 groups were race/ethnicity (PCA, 88.3% white; lvPPA, 99.0% white; amnestic AD, 80.0% white; P <.001), mean (standard deviation) educational level (PCA, 15.7 [3.2] years; lvPPA, 16.2 [3.3] years; amnestic AD, 14.8 [3.5] years; P =.02), and non-right-hand preference (PCA, 18.3%; lvPPA, 20.2%; amnestic AD, 7.7%; P =.04).
A greater proportion of participants with PCA reported a LD history vs those in the matched AD cohort (18.9% vs 3.0%, respectively; P <.001) and the general population (expected rate 10.0%; P =.007). Nonlanguage mathematical and/or visuospatial LDs were also higher in the PCA vs matched amnestic AD cohort (13.7% vs 1.0%, respectively; P <.001) and the lvPPA arm (2.4%; P =.006).
Additionally, nonlanguage mathematical LDs were more frequently reported in the PCA group vs the expected general population rate (13.7% vs 6.0%, respectively P =.003). Approximately 72.2% of LDs were found in the nonlanguage domains of patients with PCA, whereas the other patients had primarily language-only LDs. Individual patients with PCA and LDs demonstrated more right-lateralized patterns of atrophy and greater preservation of global cognition compared with patients with PCA without LDs.
The findings from the amnestic AD cohort are limited in that this group included the most nonwhite individuals compared with the PCA and lvPPA groups, and it has been speculated that these patients often have higher undiagnosed LDs compared with white patients.
Findings from this analysis “may not only assist in disease prevention and earlier detection but also [may] aid in prognosticating phenotypic presentation, prediction of clinical trajectory, and perhaps response to neurorehabilitation, underscoring the importance of capturing premorbid, neurodevelopmental differences in all adults being evaluated for cognitive impairment.”
Miller ZA, Rosenberg L, Santos-Santos MA, et al. Prevalence of mathematical and visuospatial learning disabilities in patients with posterior cortical atrophy [published online April 9, 2018]. JAMA Neurol. doi:10.1001/jamaneurol.2018.0395