- A new report suggests that prediabetes is not a robust risk factor for dementia when it does not progress to diabetes.
- Additionally, the risk of developing dementia appears to increase the younger a person develops diabetes.
- The findings highlight the need to delay — and, if possible, prevent — the progression of prediabetes to diabetes in order to protect cognitive function.
The risk of developing dementia appears to increase the younger you develop diabetes, a new study has discovered.
The report, published in the journal Diabetologia, investigated how prediabetes and its progression to diabetes are connected to dementia later in life.
Prediabetes has previously been identified as a potential risk factor for cognitive decline and dementia, however, this new report suggests that prediabetes isn’t a substantial risk factor for dementia.
The association is largely due to the fact that most prediabetes cases (70%) progress to diabetes, which is strongly associated with the risk of dementia.
In addition, the earlier people are diagnosed with diabetes, the greater their risk of developing dementia was, potentially due to long-term exposure to hyperglycemia, or high blood sugar levels.
“Basically, the younger you are if you are diagnosed with diabetes, the higher the chances you may develop memory loss and other cognitive deficits later in life. This study provides more evidence that diabetes and insulin resistance can lead to neurodegeneration,” Jonathan J. Rasouli, MD, Director, Complex and Adult Spinal Deformity Surgery at Staten Island University Hospital, told Healthline.
Early diabetes diagnoses linked to higher risk of dementia
The researchers evaluated the health data of 11,656 people who were enrolled in the Atherosclerosis Risk in Communities study and were between the ages of 45 to 64 between 1987 to 1989.
At the participants’ second visit for the study, which was held between 1990 and 1992, the researchers measured their glycated hemoglobin levels, or HbA1c, a measure of blood sugar control, along with their cognitive function.
At baseline, 2,330 participants had prediabetes. The risk of prediabetes was greatest among Black people and individuals who had less than a high school education.
All of the participants’ cognitive function was examined again at the fourth visit for the study, between 1996 and 1998, and more thoroughly at their fifth visit, held between 2011 and 2013, and during follow-up visits from there on out.
Of the group, 3,143 developed diabetes and 2,274 developed dementia.
The research team looked at the link between prediabetes and dementia and found that prediabetes does not appear to be a robust risk factor for dementia when it doesn’t progress to diabetes.
“The study found that it was indeed those patients who progressed from prediabetes to overt type 2 diabetes who were driving this association with dementia risk,” says Marilyn Tan, MD, an endocrinologist and chief of the Stanford Endocrine Clinic.
They also investigated how the age of people’s diabetes diagnosis influenced their future risk of developing dementia.
The team found that the earlier people were diagnosed with diabetes, the greater their risk of developing dementia later in life.
People who were diagnosed with diabetes before age 60 had a nearly three times greater risk of developing dementia.
Those who were diagnosed with diabetes between 60 to 69 years of age had a 73% higher risk of developing dementia and people diagnosed between ages 70 to 79 had a 23% high risk of getting dementia.
Being diagnosed with diabetes after age 80 was not associated with a higher risk of dementia.
Why diabetes may influence the risk of dementia
Scientists suspect that sustained exposure to hyperglycemia influences the risk of dementia.
“The younger one is when diagnosed with diabetes, the longer the body is exposed to hyperglycemia,” Dr. Tan says.
Hyperglycemia can affect insulin function in the brain and impair amyloid-beta clearance and increase the accumulation of tao protein in the brain — both of which are known to contribute to dementia.
In addition, high levels of glucose can be toxic and lead to inflammation and oxidative stress.
“These, in turn, lead to cellular dysfunction, damage, and the accumulation of glycation end-products. Additionally, the cellular and vascular damage could lead to impaired blood-brain barrier and the accumulation of deleterious products in brain cells,” said Benjamin Nwosu, MD, Chief of Endocrinology at the Cohen Children’s Medical Center in Queens, New York, and researcher at the Feinstein Institutes for Medical Research.
The lifestyle factors associated with diabetes, such as a poor diet and a sedentary lifestyle, can lead to cognitive decline, says Tan.
The researchers say their findings highlight the need to delay — and, if possible, prevent — the progression of prediabetes to diabetes.
Nwosu says two groups should be of focus: people diagnosed with prediabetes under the age of 65 along with Black people, who have a higher risk of being diagnosed with prediabetes.
“These findings suggest we need to be more aggressive with primary prevention and address modifiable risk factors of diabetes as early as possible. This would involve earlier screening of at-risk patients and education,” Dr. Rasouli said.
The bottom line
A new report suggests that prediabetes is not a robust risk factor for dementia when it does not progress to diabetes.
In addition, the risk of developing dementia appears to increase the younger a person develops diabetes, the new study has discovered.
The findings highlight the need to delay — and, if possible, prevent — the progression of prediabetes to diabetes in order to protect cognitive function.
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