In a new study, psychologists from the University of Southern California (USC) found that patients with untreated diabetes developed signs of Alzheimer’s disease 1.6 times faster than people without diabetes.
The research is published in the journal Diabetes Care.
“Our findings emphasize the importance of catching diabetes or other metabolic diseases in adults as early as you can,” said Dr. Daniel A. Nation, a psychologist at USC Dornsife College of Letters, Arts and Sciences.
“Among people with diabetes, the difference in their rate of developing the signs of dementia and Alzheimer’s is clearly tied somehow to whether or not they are on medication for it.”
The study is believed to be the first to compare the development rate for Alzheimer’s disease and dementia among people with normal glucose levels, those with pre-diabetes, or patients with type 2 diabetes, both treated and untreated.
The researchers focused on the “tau pathology” — the progression of the brain tangles that are the hallmark of Alzheimer’s disease. When these tangles combine with sticky beta-amyloid plaques — a toxic protein — they interfere with signals between brain cells, impairing memory and other functions.
For the study, Nation and Elissa McIntosh, a USC Dornsife Ph.D. doctoral candidate in psychology, looked at data gathered by the Alzheimer’s Disease Neuroimaging Initiative. Data included biomarkers for diabetes and vascular disease, brain scans and a variety of health indicators, including performance on memory tests.
Among 900 participants, ages 55 and older, 54 people had type 2 diabetes but were not being treated, while 67 were receiving treatment. A total of 530 had normal blood sugar levels while 250 had prediabetes (hyperglycemia).
The researchers compared, among the different diabetic patient categories, the brain and spinal fluid test results that can indicate signs of amyloid plaques and the brain tangles.
“It is possible that the medicines for treating diabetes might make a difference in the progression of brain degeneration,” Nation says. “But it’s unclear how exactly those medications might slow or prevent the onset of Alzheimer’s disease, so that is something we need to investigate.”
Alzheimer’s disease is the 6th leading cause of death in the United States. One in three seniors dies with Alzheimer’s or another type of dementia.
Increasingly, scientists regard Alzheimer’s disease as the result of a cascade of multiple problems, instead of just one or two. The compounding factors range from pollution exposure and genetics to heart disease and metabolic disease.