Individuals with Type 2 diabetes or insulin resistance have a higher risk of developing Alzheimer’s disease because they are more likely to develop plaques in the brain associated with Azheimer’s, says a new report published in the medical journal Neurology, issued August 25th, 2010. Insulin resistance is one stage before diabetes, when insulin becomes less effective in reducing blood sugar levels.

Study author Kensuke Sasaki, MD, PhD, from Kyushu University in Fukuoka, Japan, said:

Type 2 diabetes and Alzheimer’s disease are two epidemics growing at alarming levels around the world . With the rising obesity rates and the fact that obesity is related to the rise in type 2 diabetes, these results are very concerning.

The study consisted of 135 participants, all from Hisayama, Japan; their average age was 67 years. They underwent a range of diabetes glucose tests to measure their blood glucose levels. The researchers monitored them for Alzheimer’s disease symptoms for the subsequent 10 to 15 years. Approximately 16% of them developed Alzheimer’s disease.

After death, the investigators examined their brains for plaques or tangles – physical signs of Alzheimer’s disease. Only 16% had had symptoms of Alzheimer’s disease before death. However, 65% of the people who died had plaques.

The researchers discovered that those who had abnormal results on three blood sugar control tests were considerably more likely to develop plaques:

  • 72% of participants with insulin resistance had plaques
  • 62% of participants with no indication of insulin resistance had plaques

The researchers add that they did not find any association between diabetes factors and tangles in the brain.

Sasaki said:

Further studies are needed to determine if insulin resistance is a cause of the development of these plaques. It’s possible that by controlling or preventing diabetes, we might also be helping to prevent Alzheimer’s disease.

Alzheimer’s disease is a progressive neurologic disease of the brain leading to the irreversible loss of neurons and the loss of intellectual abilities, including memory and reasoning, which become severe enough to impede social or occupational functioning.

During the course of the disease plaques and tangles develop within the structure of the brain. This causes brain cells to die. Patients with Alzheimer’s also have a deficiency in the levels of some vital brain chemicals which are involved with the transmission of messages in the brain – neurotransmitters.

According the National Institute on Aging, there are estimated to be between 2.4 million and 4.5 million Americans who have Alzheimer’s. There are approximately 417,000 people in the UK with Alzheimer’s, according to the Alzheimer’s Society.

“Insulin resistance is associated with the pathology of Alzheimer disease. The Hisayama Study”
T. Matsuzaki, K. Sasaki, Y. Tanizaki, J. Hata, K. Fujimi, Y. Matsui, A. Sekita, S. O. Suzuki, S. Kanba, Y. Kiyohara, and T. Iwaki
Neurology, first published on August 25, 2010 as doi: doi:10.1212/WNL.0b013e3181eee25f

Written by Christian Nordqvist