The Mediterranean Diet Can Extend Life in Alzheimer's Disease

Internal Medicine World Report, October 2007, Volume 0, Issue 0

Neurology.

The same researchers who demonstrated that the Mediterranean diet could prevent or delay Alzheimer's disease (AD) have now provided the first evidence that this very same diet can add several years to the lives of those already diagnosed with AD ( 2007;69:1084-1093).

Nikolaos Scarmeas, MD, MSc

The study included 192 community-dwelling older adults (aged ≥65 years) who had been diagnosed with AD. The investigators assessed the patients' adherence to the Mediterranean diet, which had previously been shown to protect against a number of other chronic diseases, and the impact of diet adherence on mortality.

The Mediterranean diet is characterized by:

  • High intake of vegetables, legumes, fruits, cereals, fish, and unsaturated fats (primarily in the form of olive oil)
  • Low intake of saturated fats, meat, and poultry
  • Low-to-moderate intake of dairy products (primarily cheese or yogurt)
  • Regular, but moderate, intake of alcohol (primarily wine during meals).

After rating adherence to the diet on a scale of 0 to 9, patients were divided into tertiles of high adherence (score, 6-9), moderate adherence (4-5), and low adherence (0-3).

At 4.4 years of follow-up, 85 of the original 192 participants had died. Mean survival was 7.55 years. Unadjusted analysis showed that mean survival increased in tandem with adherence to the Mediterranean diet: 6.59 years with low adherence, 7.92 with moderate adherence, and 10.50 with high adherence. For each additional point in the adherence score, the risk of death was reduced by 21% to 24%.

APOE

After adjusting for all potential covariates—including age at recruitment, gender, ethnicity, educational level, genotype, smoking, caloric intake, and body mass index—the associations were even more pronounced. Compared with those in the low adherence tertile, mortality was reduced by 35% in the middle tertile and by 73% in the highest tertile. This positive, apparently dose-dependent, correlation remained significant after further adjustment for baseline cognitive performance and cardiovascular risk factors (diabetes, hypertension, heart disease), as well as after excluding patients who had suffered a stroke.

However encouraging these results may be, Nikolaos Scarmeas, MD, MSc, the study's lead author and assistant professor of neurology, Columbia University Medical Center, New York City, cautions, "First, the current study is an observational/epidemiological one, not a clinical trial. Second, although we are glad it is the first one, it needs to be replicated in order to have higher confidence in the finding."

IMWR

Despite these reservations, Dr Scarmeas tells , "It is well known from other observational/epidemiological studies, but also from clinical trials, that higher adherence to the MeDi [Mediterranean diet] is associated with lower risk for certain cancers, coronary heart disease, obesity, diabetes, dyslipidemia, and overall mortality. So, it makes sense to recommend it anyway. Primary care physicians are in a position to do this, since the effects are conceivably even more impressive than those of medications."

When facing the notoriously difficult task of inspiring patients to change their diets, Dr Scarmeas advises physicians to "present them with the data on protection on all the above medical conditions and diseases."

And then "mention that it is a diet that is very tasty anyway, thus easy to follow."

KEY POINTS

  • This study provides the first evidence that the Mediterranean diet can prolong the lives of patients with Alzheimer?s disease.
  • Compared with those in the low diet-adherence tertile, mortality was reduced by 35% in the middle tertile and by 73% in the highest tertile.
  • To encourage patients to follow this diet, discuss its ability to protect from other diseases, including certain cancers, heart disease, and diabetes.