Tag Archives: Alzheimers

DHA, an Omega-3 Fatty Acid, Is Again Linked to Alzheimers Disease

Dead whole fish aren't very appealing to many folks

Dead whole fish aren’t very appealing to many folks

Linked in a good way.

It’s a little complicated.

DHA is an essential fatty acid. Our bodies need DHA, and certain fish are a good sources for us.

A recent small study found that people with higher levels of bloodstream DHA have less accumulation of amyloid in their brains. Amyloid deposition is a marker of Alzheimers disease. As the dementia starts and progresses, amyloid builds up in the brain. We don’t know if the amyloid is actually causing harm to brain tissue, or is simply a bystander to some other primary disease process. Some researchers think that if we can prevent amyloid build-up, we can prevent Alzheimers.

A recent MedPageToday article reviews the new study I mentioned above:

“So what’s a clinician to do? Quinn asked. “Maybe the best advice is to adhere to the recommendations from the Centers for Disease Control and Prevention and from the American Heart Association and American Stroke Association, each of which recommend eating fish two to three times per week, primarily for vascular health,” he suggested.

Source: Role for Fatty Acid Metabolism in Preclinical AD? | Medpage Today

I’ve been recommending at least that level of consumption since 2007. Follow my Advanced Mediterranean Diet or Ketogenic Mediterranean Diet and you’ll get plenty of DHA.

Steve Parker, M.D.

PS: Fish with decent levels of DHA and other omega-3 fatty acids include salmon, trout, mackerel, sardines, herring, and albacore tuna.

“Peanut Butter Alzheimer’s Test Not Passing the Sniff Test”

Ivan Oranksy has the details at MedPageToday. Good headline!

Higher Blood Sugar Levels Once Again Linked to Dementia

dementia, memory loss, Mediterranean diet, low-carb diet, glycemic index, dementia memory loss

“Let’s work on getting those blood sugars down, honey.”

On the heels of a report finding no association between Alzheimer’s disease and abnormal blood sugar metabolism, MedPageToday features an new study linking high blood sugars to future development of dementia. And diabetics with sugar levels higher than other diabetics were more prone to develop dementia.

Some of you have already noted that not all cases of dementia are Alzheimer’s dementia. But Alzheimer’s accounts for a solid majority of dementia cases.

Some quotes from MedPageToday:

During a median follow-up of 6.8 years, 524 participants [of the 2000 total] developed dementia, consisting of 74 with diabetes and 450 without. Patients without diabetes and who developed dementia had significantly higher average glucose levels in the 5 years before diagnosis of dementia (P=0.01). The difference translated into a hazard ratio of 1.18 (95% CI 1.04-1.33).

Among the patients with diabetes, glucose levels averaged 190 mg/dL in those who developed dementia versus 160 mg/dL in those who did not. The difference represented a 40% increase in the hazard for dementia (HR 1.40, 95% CI 1.12-1.76).

Steve Parker, M.D.

Reference: Crane PK et al. “Glucose Levels and Risk of Dementia” N Engl J Med 2013; 369: 540-548.

Reminder: Conquer Diabetes and Prediabetes is now available on Kindle.

Potential Health Benefits of Alcohol

For centuries, the healthier populations in the Mediterranean region have enjoyed wine in light to moderate amounts, usually with meals. Epidemiologic studies there and in other parts of the world have associated reasonable alcohol consumption with prolonged lifespan, reduced coronary artery disease, diminished Alzheimer’s and other dementias, and possibly fewer strokes.

Alcohol tends to increase HDL cholesterol (the good stuff), have an antiplatelet effect, and may reduce C-reactive protein, a marker of arterial inflammation. These effects would tend to reduce cardiovascular disease. Wine taken with meals provides antioxidant phytochemicals (polyphenols, procyanidins) which may protect against atherosclerosis and some cancers.

What’s a “reasonable” amount of alcohol? An old medical school joke is that a “heavy drinker” is anyone who drinks more than the doctor does. Light to moderate alcohol consumption is generally considered to be one or fewer drinks per day for a woman, two or fewer drinks per day for a man. One drink is 5 ounces of wine, 12 ounces of beer, or 1.5 ounces of 80 proof distilled spirits (e.g., vodka, whiskey, gin). The optimal health-promoting type of alcohol is unclear. I tend to favor wine, a time-honored component of the Mediterranean diet. Red wine in particular is a rich source of resveratrol, which is thought to be a major contributor to the cardioprotective benefits associated with light to moderate alcohol consumption. Grape juice may be just as good—it’s too soon to tell.

Steve Parker, M.D.


Standridge, John B., et al.  Alcohol consumption: An overview of benefits and risks.  Southern Medical Journal, 97 (2004): 664-672.

Luchsinger, Jose A., et al.  Alcohol intake and risk of dementia.  Journal of the American Geriatrics Society, 52 (2004): 540-546.

Mediterranean Diet and Lifestyle Associated With Reduced Alzheimer Dementia

Alzheimer disease is a progressive brain disorder resulting in memory loss, personality change, functional impairments, and a decline in various types of thinking (e.g., math ability, problem-solving, spatial orientation). It is the most common form of dementia in the eldery, causing about 70% of cases and afflicting four million people in the U.S.

TheBostonChannel.com recently published a news release from Beth Israel Deaconess Medical Center on how to prevent Alzheimers Disease. It is a Q&A interview with Dr. Daniel Press, neurologist and Alzheimer specialist.

Dr. Press made favorable comments about the Mediterraean diet and pointed out that avoidance of obesity and diabetes may also help prevent Alzheimer disease. Regular aerobic exercise, 30 minutes daily, also seems to be protective. The potential protective effect of alcohol consumption was not mentioned.

For details on how to accomplish all this, see the Do-It-Yourself Mediterranean Diet, the Alzheimer disease prevention article at WebMD.com, or The Advanced Mediterranean Diet book.

Steve Parker, M.D.

Does Diabetes Cause Dementia?

Contrary to popular belief among the experts, type 2 diabetes is not one of the causes of Alzeimer dementia. They may indeed be associated with each other, but that’s not causation.

An oft-repeated theory from Gary Taubes 2007 masterpiece, Good Calories, Bad Calories, is that many of the chronic diseases of modern civilization, including Alzheimer disease, are caused by abnormal blood sugar and insulin metabolism. Especially high insulin levels induced by a diet rich in refined carbohydrates. If that’s the case, you’d expect to see a high prevalence of Alzheimer disease in older type 2 diabetics.

Dr. Emily Deans (psychiatrist) looked at this issue last year at her great Evolutionary Psychiatry blog.

The brains of Alzheimer patients, under a microscope, are characterized by many senile plaques (aka neuritic plaques) and neurofibrillary tangles. That’s the gold standard for diagnosis. Nevertheless, brain biopsies are rarely done to diagnose Alzheimer disease in living patients, and even autopsies after death are rare. The diagnosis usually is clinical, based on ruling out other illnesses, etc.

Nearly all the studies associating diabetes with Alzheimers disease (and other dementias) are observational or epidemiologic. (The exception is the Honolulu-Asia Aging Study.) Establishing an association is helpful in generating theories, but establishing causation is the goal. At least five studies confirm an association.

Neurology in 2011 reported findings of Japanese researchers who examined the brains of 135 people who died between 1998 and 2003. They lived in Hisayama, a town with an incredibly high autopsy rate of 74%. These people before death had undergone an oral glucose tolerance test. Their insulin resistance was calculated on the basis of fasting glucose and fasting insulin (HOMA-IR). None of them showed signs of dementia at the time of study enrollment in 1988.

What Did They Find?

Twenty-one of the 135 subjects developed Alzheimer-type dementia. The investigators don’t say if the diagnosis was based on the brain examination, or just a clinical diagnosis without a brain biopsy or autopsy. How this got beyond the article reviewers is beyond me. [If I’m missing something, let me know in the comments section below.] It must be a clinical diagnosis because if you don’t act demented, it doesn’t matter how many senile plaques and neurofibrillary tangles you have in your brain.

Senile plaques, but not neurofibrillary tangles, were more common in those with higher levels of blood sugar (as measured two hours after the 75 g oral glucose dose), higher fasting insulin, and higher insulin resistance. People with the APOE epsilon-4 gene were at even higher risk for developing senile plaques.

The researchers did not report whether the subjects in this study had been diagnosed during life with diabetes or not. One can only hope those data will be published in another paper. Why make us wait?

Average fasting glucose of all subjects was 106 mg/dl (5.9 mmol/l); average two-hour glucose after the oral glucose load was 149 mg/dl (8.3 mmol/l). By American Association of Clinical Endocrinologists criteria, these are prediabetic levels. Mysteriously, the authors fail to mention or discuss this. [I don’t know if AACE criteria apply to Japanese.] Some of these Japanese subjects probably had diabetes, some had prediabetes, others had normal glucose and insulin metabolism.

As with all good research papers, the authors compare their findings with similar published studies. They found one autopsy study that tended to agree with their findings (Honolulu) and three others that don’t (see references below). In fact, one of the three indicated that diabetes seems to protect against the abnormal brain tissue characteristic of Alzheimer disease.

Botton Line

Type 2 diabetes doesn’t seem to be a cause of Alzheimer disease, if autopsy findings and clinical features are the diagnostic criteria for the disease.

If we assume that type 2 diabetics have higher than normal blood sugar levels and higher insulin levels for several years, then hyperglycemia and hyperinsulinemia don’t cause or contribute to Alzheimer dementia.

Type 2 diabetes is, however, linked with impaired cognitive performance, at least according to many of the scientific articles I read in preparation for this post. So type 2 diabetics aren’t in the clear yet. It’s entirely possible that high blood sugar and /or insulin levels cause or contribute to that. (Any volunteers to do the literature review? Best search term may be “mild cognitive impairment.”)

Type 2 diabetes is associated with Alzheimer disease, but we have no proof that diabetes is a cause of Alzheimers. Nor do we have evidence that high blood sugar and insulin levels cause Alzheimer disease.

Alzheimer disease is a major scourge on our society. I’d love to think that carbohydrate-restricted eating would help keep blood sugar and insulin levels lower and thereby lessen the devastation of the disease. Maybe it does, but I’d like to see more convincing evidence. It’ll be years before we have a definitive answer.

For now, we have evidence that the Mediterranean diet seems to 1) protect againstAlzheimers and other dementias, 2) prevent some cases of type 2 diabetes, and 3) reduce the need for diabetic medications in diabetics.

For more information on practical application of the Mediterranean diet, visit Oldways and the Advanced Mediterranean Diet website.

Steve Parker, M.D.


Matsuzaki T, Sasaki K, Tanizaki Y, Hata J, Fujimi K, Matsui Y, Sekita A, Suzuki SO, Kanba S, Kiyohara Y, & Iwaki T (2010). Insulin resistance is associated with the pathology of Alzheimer disease: the Hisayama study. Neurology, 75 (9), 764-70 PMID: 20739649

Heitner, J., et al. “Diabetics do not have increased Alzheimer-type pathology compared with age-matched control subjects: a retrospective postmortem immunocytochemical and histofluorescent study.” Neurology, 49 (1997): 1306-1311. Autopsy study, No. of subjects not in abstract. They looked for senile plaques and neurofibrillary tangles, etc. The title says it all.

Beeri, M.S., et al. “Type 2 diabetes is NEGATIVELY [emphasis added] associated with Alzheimer’s disease neuropathology.” J. Gerontol A. Biol Sci. Med. Sci. 60 (2005): 471-475. 385 autopsies. The title again says it all.

Arvanitakis, Z., et al. “Diabetes is related to cerebral infarction but NOT [emphasis added] to Alzheimers disease pathology in older persons.” Neurology, 67 (2006): 1960-1965. Autopsy study of 233 Catholic clergy, about 50:50 women:men.