Cognitive Deficits Complex in Youths With Type 2 Diabetes

Andrew D. Bowser

July 02, 2020

Teens and young adults with diabetes have cognitive deficits that vary by diabetes type and could negatively impact their medical literacy and self-care, an investigator reported at the virtual annual scientific sessions of the American Diabetes Association.

Individuals with youth-onset type 1 or 2 diabetes all performed below average on tests that measure flexible thinking and problem solving, according to the investigator, who reported an analysis including 1,380 individuals enrolled in the SEARCH for Diabetes in Youth study.

That finding suggests that diabetes diagnosed before age 20 contributes to poor fluid cognitive function, which consists of skills that facilitate goal-directed behaviors, according to investigator Allison Shapiro, MPH, PhD, of the University of Colorado at Denver, Aurora.

However, individuals with type 2 diabetes (T2D) performed even worse than those with type 1 diabetes (T1D) on the fluid cognitive function tests, even after adjustment for demographic factors and other confounders, Dr. Shapiro said in her presentation.

Further analysis revealed that individuals with T2D performed significantly worse on measures of crystallized cognition, a domain that includes skills such as vocabulary and language. That suggests the poor fluid cognitive abilities in youths with diabetes may in fact be a result of poor crystallized cognitive development, according to the investigator.

"Among adolescents and young adults with youth-onset type 2 diabetes specifically, intervention should focus on developing both fluid cognitive skills and crystallized cognitive skills," Dr. Shapiro said.

Deficits in fluid cognitive function (such as reasoning or processing speed) can negatively affect diabetes self-care, thereby potentially increasing the risk of diabetes-related complications, while deficits in crystallized cognitive function (such as vocabulary and understanding of language) could impact medical literacy further compounding the self-care issues.

The study is believed to be one of the first to compare cognitive function deficits in youths with type 1 or 2 diabetes. Although studies in adults clearly show a detrimental relationship between diabetes and cognitive function, according to Dr. Shapiro, the bulk of the research in youths has focused on T1D.

"While limited work has been done in youth-onset type 2 diabetes, cognitive deficits are consistently observed, compared to youth without diabetes," she said.

Results of this study emphasize the importance of dietary changes and other lifestyle interventions in young patients with diabetes, according to David Della-Morte, MD, PhD, associate professor of neurology at the University of Miami.

"Even the youngest patients may develop cognitive dysfunction," Dr. Della-Morte said in an interview. "That means that lifestyle is very important, especially in obese patients that are prone to develop type 2 diabetes."

The analysis by Dr. Shapiro and coinvestigators included 1,095 youths and young adults with T1D and 285 with T2D who had undergone a cognition assessment as part of a study visit. They were aged an average of 22 years, and had an average diabetes duration of 11 years.

The overall fluid cognition score was significantly lower in those individuals with T2D, compared with those with T1D, investigators found. Compared with the national average score of 100, the T2D group scored 84.7, or a full standard deviation below that average, said Dr. Shapiro, while those with T1D scored 95.5 (P < .001).

Participants with T2D also scored significantly lower in individual measures of fluid cognition, including processing speed, inhibitory control and attention, working memory, and episodic memory, she reported. At first glance, that suggested youth-onset T2D has a specific effect on fluid cognition; however, the story remains incomplete without looking at crystallized cognition markers such as vocabulary and language.

Toward that end, a picture vocabulary test conducted as part of the cognitive assessment showed a significant difference between those with T2D, who on average scored 91.5, and those with T1D, who scored 103.6 (P < .001). Accounting for those picture vocabulary scores attenuated the differences between groups in fluid cognitive scores, suggesting that differences in crystallized cognitive function underly the observed differences in fluid cognitive function between groups, Dr. Shapiro said.

Skills such as vocabulary and language are thought to be stable and not influenced by neurologic changes brought on by disease processes such as youth-onset diabetes, but rather, influenced by factors such as childcare and education, according to Dr. Shapiro.

"Crystallized cognition therefore provides a window into an individual's cognitive functioning, independent of their disease or premorbid to the onset of their disease," she said.

Dr. Shapiro said she had no conflicts of interest to disclose.

SOURCE: Shapiro A et al. ADA 2020, Abstract 279-OR.

This article originally appeared on MDedge.com.

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