Managing biological age through diet can reduce risk
By David Dunaief, M.D.
Dementia may be diagnosed when someone experiences loss of memory plus loss of another faculty, such as executive functioning (decision-making) or language abilities (speaking, writing or reading). The latter is known as aphasia. Alzheimer’s disease is responsible for approximately 60 to 80 percent of dementia cases (1).
Unfortunately, there are no definitive studies that show reversal or a cure for Alzheimer’s disease. This is why prevention is central to Alzheimer’s — and dementia in general.
In terms of dementia, there is good news and some disappointing news.
We will start with the good news. Though chronological age is a risk factor that cannot be changed, biological age may be adjustable. There are studies that suggest we may be able to prevent dementia through the use of both lifestyle modifications and medications.
Telomeres’ length and biological age
Biological age may be different from chronological age, depending on a host of environmental factors that include diet, exercise and smoking. There are substances called telomeres that are found at the ends of our chromosomes. They provide stability to this genetic material. As our telomeres get shorter and shorter, our cellular aging and, ultimately, biological aging, increases.
In a preliminary case-control study, dementia patients were shown to have significantly shorter telomere length than healthy patients (2). Interestingly, according to the authors, men have shorter telomere length and may be biologically older by four years than women of the same chronological age. The researchers caution that this is a preliminary finding and may not have clinical implications.
What I find most intriguing is that intensive lifestyle modifications increased telomere length in a small three-month study with patients who had low-risk prostate cancer (3). By adjusting their lifestyles, study participants were potentially able to decrease their biological ages.
Lifestyle modifications play a role in many chronic diseases and disorders. Dementia is no exception. In a prospective observational study, involving 3,790 participants, those who had the greatest compliance with a Mediterranean-type diet demonstrated a significant reduction in the risk of Alzheimer’s disease, compared to the least compliant (4). Participants were over the age of 65, demographics included substantial numbers of both black and white participants, and there was a mean follow-up of 7.6 years. Impressively, those who adhered more strictly to the diet performed cognitively as if they were three years younger, according to the authors.
Beta-carotene and vitamin C effect
In a small, preliminary case-control study (disease vs. healthy patients), higher blood levels of vitamin C and beta-carotene significantly reduced the risk of dementia, by 71 and 87 percent, respectively (5). The blood levels were dramatically different in those with the highest and lowest blood levels of vitamin C (74.4 vs. 28.9 µmol/L) and beta-carotene (0.8 vs. 0.2 µmol/L).
The reason for this effect may be that these nutrients help reduce oxidative stress and thus have neuroprotective effects, preventing the breakdown of neurons. This study was done in the elderly, average 78.9 years old, which is a plus, since as we age we’re more likely to be afflicted by dementia.
It is critically important to delineate the sources of vitamin C and beta-carotene in this study. These numbers came from food, not supplements. Why is this important? First, beta-carotene is part of a family of nutrients called carotenoids. There are at least 600 carotenoids in food, all of which may have benefits that are not achieved when taking beta-carotene supplements. Second of all, beta-carotene in supplement form may increase the risk of small-cell lung cancer in smokers (6).
Foods that contain beta-carotene include fruits and vegetables such as berries; green leafy vegetables; and orange, red or yellow vegetables like peppers, carrots and sweet potato. It may surprise you, but fish also contains carotenoids. In my practice, I test for beta-carotene and vitamin C as a way to measure nutrient levels and track patients’ progress when they are eating a nutrient-dense diet. Interestingly, many patients achieve more than three times higher than the highest beta-carotene blood levels seen in this small study.
Impact of high blood pressure medications
For those patients who have high blood pressure, it is important to know that not all blood pressure medications are created equal. When comparing blood pressure medications in an observational study, two classes of these medications stood out. Angiotensin II receptor blockers (known as ARBs) and angiotensin-converting enzyme inhibitors (known as ACE inhibitors) reduce the risk of dementia by 53 and 24 percent respectively, when used in combination with other blood pressure medications.
Interestingly, when ARBs were used alone, there was still a 47 percent reduction in risk; however, ACE inhibitors lost their prevention advantage. High blood pressure is a likely risk factor for dementia and can also be treated with lifestyle modifications (7). Otherwise, ARBs or ACE inhibitors may be the best choices for reducing dementia risk.
Ginkgo biloba disappoints
Ginkgo biloba, a common herbal supplement taken to help prevent dementia, may have no benefit. In the GuidAge study, ginkgo biloba was shown to be no more effective than placebo in preventing patients from progressing to Alzheimer’s disease (8). This randomized controlled trial, considered the gold standard of study designs, was done in elderly patients over a five-year period with almost 3,000 participants. There was no difference seen between the treatment and placebo groups. This reinforces the results of an earlier study, Ginkgo Evaluation of Memory trial (9). Longer studies may be warranted. The authors stressed the importance of preventive measures with dementia.
Fish oil: not the last word
Many of us take fish oil supplements in the hope of preventing dementia. However, in a meta-analysis (a group of three randomized controlled trials), the results did not show a difference between treatment groups and placebo in older patients taking fish oil with omega-3 fatty acids (10). The authors stress that this is not the final word since studies have been mixed.
The longest of the three studies was 40 months, yet may not have been long enough to see a beneficial effect. Also participants in the meta-analysis did not necessarily have low omega-3 levels at the beginning of the studies. This doesn’t necessarily mean fish oil doesn’t work for dementia prevention, it is just discouraging, as the authors emphasize. Fish consumption, however, has shown an inverse association with Alzheimer’s and dementia overall (11).
There may be ways to prevent dementia from occurring, whether through lifestyle modifications or through the selection of medications, if they are necessary.
(1) www.uptodate.com. (2) Arch Neurol. 2012 Jul 23:1-8. (3) Lancet Oncol. 2008;9(11):1048-1057. (4) Am J Clin Nutr. 2011;93:601-607. (5) J Alzheimers Dis. 2012;31:717-724. (6) Am. J. Epidemiol. 2009; 169(7):815-828. (7) Neurology. 2005;64(2):277. (8) Lancet Neurol. 2012;11(10):851-859. (9) JAMA. 2008;300(19):2253-2262. (10) Cochrane Summaries online June 13, 2012. (11) Neurology. 2007;69(20):1921.
Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com or consult your personal physician.