By Dr. Mercola
Insulin resistant people with type 2 diabetes are more likely to develop plaques in their brains which are associated with Alzheimer's disease.
A study looked at 135 elderly participants who were monitored for signs of Alzheimer's disease for 10 to 15 years.
After they died, researchers conducted autopsies on their brains and that those who had high blood sugar levels while they were alive also tended to have the plaques.
According to Reuters:
“Twenty-one participants, or 16 percent, developed Alzheimer's disease before they died and plaques were found in all of their brains. But the autopsies also found plaques in other participants who had abnormally high blood sugar levels.
Plaques were found in 72 percent of people with insulin resistance and 62 percent of those with no indication of insulin resistance, the researchers wrote.
"The point is that insulin resistance may possibly accelerate plaque pathology (development)," Sasaki wrote.”
Reuters August 25, 2010
Journal of Neurology, Neurosurgery and Psychiatry June 11, 2010; [Epub ahead of print]
Dr. Mercola's Comments:
This is not the first time researchers have connected diabetes with Alzheimer’s. In fact, Alzheimer’s disease was tentatively dubbed “type 3 diabetes” in early 2005when researchers realized that your pancreas is not the only organ that produces insulin.
Your brain also produces insulin, and this brain insulin is necessary for the survival of your brain cells. But interestingly, while low insulin levels in your body are associated with improved health, the opposite appears to be true when it comes to your brain insulin.
A drop in insulin production in your brain contributes to the degeneration of brain cells, and studies have found that people with lower levels of insulin and insulin receptors in their brain often have Alzheimer’s disease.
A 2004 study also revealed that people with diabetes have a 65 percent higher risk of developing Alzheimer’s disease.
New Evidence Strengthening the Link Between Diabetes and Alzheimer’s Disease
According to this recent Japanese study, insulin resistance and/or diabetes appear to accelerate the development of plaque in your brain, which is a hallmark of Alzheimer’s.
This study, which had a very long observation period, further strengthens the link between these two diseases, as different as they may otherwise appear to be.
Previous research have already found a strong correlation between body mass index (BMI) and high levels of beta-amyloid, the protein that tends to accumulate in the brains of Alzheimer's patients, causing plaque buildup. It is believed that beta-amyloid destroys nerve cells, contributing to the cognitive and behavioral problems typical of the disease.
In this study, which monitored 135 people for 10 to 15 years, 16 percent developed Alzheimer’s disease before they died, and autopsy showed they all had plaque in their brains.
However, 72 percent of those with insulin resistance also had plaque, as well as 62 percent of those who did not have insulin resistance yet had very high blood sugar levels.
The authors believe that insulin resistance speeds up the development of plaque, hence accelerating and increasing your risk of developing Alzheimer’s as you age.
Genetic Factors May Increase or Decrease Your Risk
Genetic factors may also play a role in whether diabetes will dramatically increase your risk of dementia.
A 2003 reviewof the available research at the time stated that the number of people with Alzheimer’s and diabetes may have been underestimated, simply because people with suspected vascular dementiawere typically excluded from an Alzheimer’s diagnosis.
The author stated:
“When people with cerebrovascular disease are included, diabetes is associated with an increased risk for Alzheimer's disease. Studies that have examined peripheral glucoregulation in Alzheimer's disease are not consistent but some show small to moderate impairments in insulin sensitivity.
One recent study suggest that in people that have both diabetes and an ApoE4 allele, the risk of developing Alzheimer's disease is more than double the risk of people with an ApoE4 allele without diabetes.
Although diabetes does not produce any of the usual brain pathology associated with Alzheimer's disease, one study has shown that diabetes dramatically increases the amyloid deposition and neurofibrillary tangles in people with the ApoE4 genotype.
Taken together, the data available suggest that diabetes is probably a risk factor for Alzheimer's disease mainly through the cerebrovascular disease diabetes causes. In people with other risk factors such as ApoE4 allele, diabetes appears to lead to a more dramatic increase in Alzheimer's disease pathology.”
The APOE ε4 gene is known to influence many neurological diseases, and is considered a high risk factor for Alzheimer's. So, in a nutshell, if you have this particular gene, AND are insulin resistant or have diabetes, your risk of developing Alzheimer’s may be significantly increased.
This is yet another example of how you can overcome genetic predispositions through lifestyle choices. Because if you have this genetic risk factor for dementia, but maintain a lifestyle that prevents you from becoming diabetic, your genetic risk factor is significantly reduced.
The Major Four Culprits Causing Alzheimer’s
According to the University of Michigan, dementia strikes about 50 percent of people who reach the age of 85. Of those, about 60 percent go on to develop Alzheimer's disease.
So far, insulin resistance appears at the top of the list of known culprits contributing to dementia, but there are a few other factors that can also cause or add to the nerve damage that leads to Alzheimer’s disease, such as:
Insufficient omega-3 fats
Certain drugs -- Anticholinergic drugsis one class of drugs that have been linked to increased risk of dementia and Alzheimer’s disease. Available both over-the-counter and by prescription, anticholinergic drugs include night-time pain relievers, antihistamines, and other sleep aids.
Anticholinergic drugs block a nervous system neurotransmitter called acetylcholine. Those suffering from Alzheimer's disease typically have a marked shortage of acetylcholine.
One recent studyfound that seniors who took drugs classified as 'definite anticholinergics' had a four times higher incidence of cognitive impairment.
Interestingly, in those who were not carriers of the specific gene, APOE ε4 allele (which predisposes you to neurological disease, as mentioned above), the risk was over seven times higher! And taking two of these drugs further increased the risk of cognitive impairment.
So, although you may NOT have a genetic predisposition, your drug use can negate this inherent benefit... just as diet and lifestyle can help you overcome a detrimental genetic factor. Even more reason to ditch the drugs and focus on a healthful lifestyle!
Six Guidelines to Prevent Alzheimer's Disease, While Combating Diabetes at the Same Time
Clearly, the best “treatment” for Alzheimer’s disease is prevention, not drugs.
And, although science is now starting to catch up and providing the actual scientific evidence to support my advice, my top three recommendations for Alzheimer’s prevention are identical to those for combating insulin resistance, and have been for some time.
This is because the single most important physical factor that is responsible for accelerating nearly every chronic disease known to man is to normalize your insulin and leptin levels.
Interestingly, this normalization will typically lower insulin and leptin levels in your body while raising your production of brain insulin.
The following seven guidelines can help you prevent Alzheimer’s disease and keep your mind sharp as you age:
Avoid sugars and grains, particularly fructose. Eating a nutritious diet that is low in fructose, added sugars and grains, and high in fresh vegetables (which are high in folate), is one of the best things you can do to prevent diabetes, dementia, and a variety of other chronic diseases.
Ideally you’ll want to devise a nutritional plan geared to your specific nutritional type to maximize the health benefits. I believe this is so essential to everyone’s health, I’m very pleased to now be able to offer the full online nutritional typing program for free.
Take a high quality animal-based omega-3 fat.I recommend consuming high quality krill oilto meet the optimal amount of omega-3 fats needed to achieve good health and fight Alzheimer's. I recently did a five hour interview with an industry expert which goes into great detail as to why I am strongly recommending krill. That interview should be published in a few weeks.
Increase your intake of antioxidants. Wild blueberries, for example, have high anthocyanin and antioxidant content that are known to guard against Alzheimer's and other neurological diseases.
Exercise. We all know that exercise is good for our cardiovascular system, but studies have found that exercise can also protect your brain, thereby warding off Alzheimer's and other forms of dementia.
According to one study, the odds of developing Alzheimer's were nearly quadrupled in people who were less active during their leisure time, between the ages of 20 and 60, compared with their peers.
Similar to a healthy diet, regular physical activity is one of those things that can significantly improve many aspects of your physical and emotional health. For the elderly, simple activities such as walkingand light weight training would likely provide benefits. For those who are younger, more strenuous exercise may heighten the benefits.
Avoid and remove mercury from your body. Even trace amounts of mercury can cause the type of damage to nerves that is characteristic of the damage found in Alzheimer's disease.
Dental amalgam fillingsare one of the major sources of mercury, however you should be healthy prior to having them removed. Once you have adjusted to your improved diet, you can follow my mercury detox protocoland then find a biological dentistto have your amalgams removed.
Other sources of mercury include most seafood, thimerosal-containing vaccinationsand flu shots, which contain both mercury and aluminum.
Avoid aluminum. Aluminum has been widely associated with Alzheimer's disease. Your main sources of exposure are likely through drinking waterand antiperspirants.
Aluminum cookware may also be a source of exposure. Although aluminum pots are probably less problematic than the sources mentioned above, I personally would not use aluminum cookware.
Challenge your mind. Mental stimulation, such as traveling, learning to play an instrument or doing crossword puzzles, is associated with a decreased risk of Alzheimer's. Researchers suspect that mental challenge helps to build up your brain, making it less susceptible to the lesions associated with Alzheimer's disease.