Genotype Associated with Black Race Linked to Cognitive Decline in Black Diabetes Patients

A study recently published in JAMA Network Open found a correlation between a genotype frequently carried by black people and greater cognitive decline in type 2 diabetes patients.

For the study, researchers analyzed haptoglobin (Hp) 1-1, which is correlated with poor cognition and cerebrovascular disease, and Hp 2-1 and Hp 2-2, which are linked to increased myocardial infarction and mortality risk. They also looked at Hp 2-1m, which is found in people of African descent.

“African American adults have a higher prevalence of Hp 1-1 (approximately 30%) compared with individuals of white race/ethnicity (approximately 14%), but the potential role of the Hp genotype in cognition among elderly African American individuals with type 2 diabetes is unknown,” the researchers wrote. Black patients are also more likely to develop diabetes or dementia than white patients.

In African American diabetics, the haptoglobin 1-1 genotype is linked to poorer cognition while the 2-1m genotype is linked to better cognition. Learn more: https://t.co/G14QXpJoff pic.twitter.com/olVI8V2iN3

— JAMA Network Open (@JAMANetworkOpen) November 11, 2018

Data were collected from the Action to Control Cardiovascular Risk in Diabetes–Memory in Diabetes (ACCORD-MIND) study, a multi center clinical study, on 466 elderly black participants (mean age, 62.3 years; 64.8% were female) with type 2 diabetes. The ACCORD trial took place from Oct. 28, 1999, to Sept. 15, 2014. Cognitive function and change after 40 months was evaluated using the 30-point Mini-Mental State Examination (MMSE). Greater scores indicate better cognition.

Genotype presence among the participants were 29.4% (n = 137) for Hp 1-1, 36.1% (n = 168) for Hp 2-1, 10.9% (n = 51) for Hp 2-1m, and 23.6% (n = 110) for Hp 2-2. At baseline, Hp 1-1 patients had the lowest MMSE score (mean [SE], 25.68), while Hp 2-1m had the highest (mean [SE], 27.15). After 40 months, significant cognitive decline was observed in Hp 1-1 (mean [SE], −0.41; P = 0.04) and Hp 2-2 patients (mean [SE], −0.68; P = 0.001). In Hp 1-1 patients, age had a strong association with MMSE score decline estimate per year change (mean [SE], −0.87; P = 0.005), but the same correlation was not observed in Hp 2-1 (mean [SE], 0.06; P = 0.85), Hp 2-1m (mean [SE], −0.06; P = 0.89), and Hp 2-2 patients (mean [SE], −0.44; P = 0.29). This suggests that “cognitive decline in Hp 1-1 carriers was accentuated in older ages, whereas it was not significant for the other Hp genotypes,” the study authors wrote.

“To our knowledge, this is the first study to investigate the role of the Hp genotype in cognitive function and decline among elderly African American adults with type 2 diabetes, who are at particularly high risk of developing dementia1-3 and other type 2 diabetes complications,” the researchers stated, adding, “The Hp gene polymorphism may explain the elevated dementia risk in African American adults.

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Source: JAMA Network Open