Developmental History Skews Alzheimer’s Diagnosis

Vignesh Subramanian ’24

Figure 1: Older adults with histories of reading difficulty garner diagnostic test scores indicative of AD risk factors.

Alzheimer’s disease (AD) is a neurodegenerative disease that, alongside related dementias, afflicts nearly 50 million people worldwide with incidence rates increasing with age. Alzheimer’s is particularly debilitating in areas of language and memory, contributing to progressive cognitive decline that is frequently diagnosed using neuropsychological tests evaluating recall, visual processing and executive function. Yet while such assessments are meant to ascertain whether patients suffer from mild cognitive impairment (MCI), individuals with differing developmental histories who perform similarly are also flagged as sharing potential AD risk factors, often inaccurately. A study led by Dr. Lebowitz of Stony Brook University in conjunction with Boston University hypothesized that MCI classification could be inaccurately interpreted due to an individual’s subjective characterization of his or her symptoms and insufficient testing.

Researchers examined the correlation between MCI classification and suspected reading disorder (SRD) based on inference in 1,804 community dwelling adults divided into two groups, one experimental (for SRD patients) and one control (normal readers, or NR). The SRD group was scaled to account for varying educational histories and literacy, further subdividing the group into “no high school degree”, “high school degree” and “college degree” categories to eliminate the influence of intellect.. All subjects were then submitted to three separate memory measures assessing their ability to recall a logically organized story (the LM-DR test), to recall paired objects and words (the PA-DR test), and to recall and draw designs (the VR-DR test) following delay periods, as well as a single word diction test known as TMT. While all of these measures center on recollection by evaluating episodic memory and complex attention, a full neuropsychological test battery typically also involves modules aimed at assessing attentional capacity and the possible presence of aphasia. 

The intentionally incomplete assessment battery still resulted in a strong correlation between substandard reading ability and low recall test scores, suggesting that even SRD patients with no history of dementia could display associated symptoms. Individuals with lifelong learning and translational difficulties manifested in SRDs were in fact two to three and a half times more likely than other subjects to garner scores suggestive of memory decline on two tests. The study thus emphasized that a failure to establish neuropsychological testing foci beyond memory alone likely contributes to misdiagnosis of Alzheimer’s disease in patients with reading difficulty, indicating a need for additional examination of patients’ comorbid or alternative cognitive vulnerabilities in clinical practice. 

Works Cited:

[1] B. Lebowitz, et al., Lifelong Reading Disorder and Mild Cognitive Impairment: Implications for Diagnosis. Journal of Alzheimer’s Disease 50, 41-45 (2016). doi: 10.3233/JAD-150543

[2] Image retrieved from: https://commons.wikimedia.org/wiki/File:Open_book_nae_02.svg

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s