Biomarkers of Alzheimer's disease identified in young adults with diabetes

With obesity rates rising in the United States and around the world, the prevalence of diabetes is expected to also increase, affecting more young people.

Previous studies have shown that people over 40 with these biomarkers are 60 to 80 percent more likely to develop dementia or Alzheimer's disease.

A new study shows that biomarkers linked to the development of Alzheimer's disease (AD) later in life are present in people with type 1 and type 2 diabetes that began at a young age.

The study authors observed blood biomarkers associated with Alzheimer's disease, as well as elevated levels of amyloid protein in brain areas associated with Alzheimer's disease, in adolescents and young adults with diabetes.

The study is the first to examine the presence of these potential preclinical signs of Alzheimer's disease in adolescents and young adults. The research was recently published in the journal Endocrines.

"There is a growing body of research examining how the pathophysiology of diabetes may contribute to the development of Alzheimer's disease and dementia," said first author Allison L. Shapiro, MD, MPH, assistant professor of pediatric endocrinology at the University of Colorado.

"The main hypotheses include insulin dysregulation (eg, insulin resistance and impaired insulin secretion) and hyperglycemia," she said.

What is the connection between diabetes and Alzheimer's disease?

The authors of the current study note that previous research has shown that people with adult-onset diabetes are 60 to 80 percent more likely to develop dementia or Alzheimer's disease than those without diabetes.

For the new study, researchers from the University of Colorado Anschutz Medical Campus analyzed data from the SEARCH cohort.

In this cohort, 25 people had type 1 diabetes and 25 people had type 2 diabetes. The average age of the youngest group was 15 years, and the young adults were about 27 years old. Of the entire group, 59% were women.

A healthy control group provided a basis for comparison. It included 25 adolescents in their early 15s and 21 young adults with an average age of about 25.

Blood plasma from the SEARCH cohort was analyzed for Alzheimer's disease biomarkers. In addition, seven people with diabetes from the cohort and six controls were recruited for PET brain scans in the new study.

People with young-onset diabetes were found to have higher levels of blood biomarkers associated with Alzheimer's disease.

The scans revealed the presence of densities of amyloid and tau — both associated with Alzheimer's disease — in Alzheimer's-related brain regions among those who had the biomarkers. However, these differences did not reach statistical significance.

What type of diabetes is linked to Alzheimer's disease?

Shapiro said the study was too small to determine which type of diabetes carried a greater risk.

"We'll need larger groups of people and longer observation times to fully answer this question," she said.

It is also not yet known whether a person with diabetes that began at a young age will continue to show biomarkers associated with Alzheimer's disease as they age.

"Other studies in adults who developed diabetes in adulthood have shown similar trends to what we found in our young adults with young-onset diabetes," Shapiro said.

"Taken together with the data in adults, we would expect that the trends we see in young adults will continue into later life."

Courtney Kloske, PhD, director of scientific affairs for the Alzheimer's Association, who was not involved in the study, noted that both Alzheimer's and diabetes are complex diseases.

"Research shows that they have some common underlying mechanisms, such as disturbances in energy production by certain cells," Kloske said.

Kloske noted that diabetes and cardiovascular problems such as hypertension and cholesterol problems are risk factors for cognitive impairment and dementia, including Alzheimer's disease.

Kloske cautioned against taking the study as definitive, saying it has limitations that mean "we can't take their findings as definitive, but they certainly merit further research."

She said the study was too small and preliminary to "test the idea that early diabetes may begin a series of changes in the brain that eventually lead to cognitive decline and/or dementia."

What can reduce the risk of Alzheimer's disease?

"While research into diabetes and Alzheimer's disease is accelerating, there is still not enough information to determine exactly what it is about diabetes that contributes to the increased risk of Alzheimer's disease and dementia," Shapiro said.

“For people with diabetes, continuing to monitor their blood sugar levels is a good practice to prevent diabetes complications. This practice may also help prevent an increased risk of cognitive problems due to Alzheimer’s disease and dementia.” — Allison L. Shapiro, MD, MPH, first author of the study

The most immediate action that can be taken for people at high risk is regular cognitive testing to monitor the progression of dementia or Alzheimer's disease.

"Risk factors for Alzheimer's disease and other dementias occur throughout life," Kloske said.

"The earlier we can identify changes in the brain and intervene, and the longer we can practice brain-healthy habits, the better," she added.

Kloske noted that the Alzheimer's Association provides recommendations for maintaining brain health, highlighting the following health and lifestyle recommendations:

• regular physical activity,
• diabetes and blood pressure management,
• avoiding smoking,
• good sleep,
• balanced diet.

Kloske also mentioned a study called US POINTER.

The two-year clinical trial, she explained, “is assessing whether lifestyle interventions that simultaneously target multiple risk factors can protect cognitive function in older adults (aged 60-79 years) at increased risk of cognitive decline.” Data and results from the trial are expected in 2025.