Alzheimer Disease in Persons With Learning Disorders—What Is the Connection?
Newly published research suggests that certain types of learning disorders (LDs) associated with neurodevelopmental differences in specific brain networks are linked to the development of neurodegenerative diseases such as Alzheimer disease (AD) later in life.
Previous research has shown an increased occurrence rate of language-based LDs in persons with AD-related primary progressive aphasia (PPA). In their study, researchers at the UCSF Weill Institute for Neurosciences at the University of California, San Francisco, hypothesized that, correspondingly, persons with AD-related focal neurodegenerative syndromes (such as posterior cortical atrophy [PCA]) not affecting the brain network responsible for language would more often develop non–language-based LDs.
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The researchers designed a case-control study of 279 adult patients—179 with atypical AD, 95 of whom had PCA and 84 of whom had PPA; and an age- and sex-matched cohort of 100 control patients with amnestic AD. The patients had presented from March 1, 1999, to August 31, 2014. The researchers compared the cognitive test results and brain imaging findings of patients with and without a previously identified LD, seeking to determine the prevalence and type of LDs present in patients with PCA and PPA.
The results of their analysis showed that patients with PCA and PPA had higher occurrence rates of LDs compared with the general population and the control group of patients with AD. Moreover, they found that the group of patients with PCA had a significantly higher number of nonlanguage (mathematical and visuospatial) LDs than the general population and the patients with AD.
“Nonlanguage mathematical and visuospatial LDs were associated with focal, visuospatial predominant neurodegenerative clinical syndromes,” the authors concluded. They note that these findings support their hypothesis that domain-specific LDs may be associated with domain-specific neurodegenerative diseases, “raising the possibility that neurodevelopment is associated with targeting and selective vulnerability to neurodegenerative disease.”
—Michael Gerchufsky
Reference:
Miller ZA, Rosenberg K, Santos-Santos MA, et al. Prevalence of mathematical and visuospatial learning disabilities in patients with posterior cortical atrophy. JAMA Neurol. 2018;75(6):728-737. doi:10.1001/jamaneurol.2018.0395.