A panel of fifteen experts examined the available treatments for Alzheimer's disease in a three-day meeting for the National Institute of Health, according to the Wall Street Journal Health Blog. The experts concluded that the available research doesn't indicate that any intervention actually prevents the disease -- interventions include both medications and herbal supplements.
Specifically, the panel's report states, "There is insufficient evidence to support the use of pharmaceutical agents or dietary supplements to prevent cognitive decline or Alzheimer's disease." However, the report goes on to say that current studies show promise in the prevention of the disease (and/or the delay of cognitive decline), including those of antihypertensive (high blood pressure) medications, omega-3 fatty acid, physical activity, and cognitive engagement.
Even analyzing the available data proved to be a challenge, due primarily to the fact that the definition of Alzheimer's disease isn't consistent across all research. We mentioned in a previous blog post that the diagnosis of the disease is based on a cognitive assessment which tends to be subjective, and even researchers will use slightly differing standards to define the disease.
The wide variety of possible risk factors and causes also cause problems for experts attempting to disseminate the information. Determing whether a given factor is a cause or merely an association can be difficult, because so many factors are inter-related. For example, higher education may be linked to a decreased risk of Alzheimer's disease, but higher education is also associated with cognitive engagement.
Here's what the panel found among a few prominent factors:
- Omega-3 fatty acids - such as those found in fish - have shown a decreased risk for cognitive decline in several longitudinal studies.
- A number of cardiovascular conditions have been linked to an increased risk of cognitive decline. High blood pressure shows the strongest association.
- Depression and depressive symptoms have a consistent correlation with cognitive decline.
- Socioeconomic factors show little correlation with cognitive decline.
- Physical activity and participation in leisure activities can help preserve cognitive function.
- Current smoking can increase the risk of cognitive decline, but no association was found with alcohol use.
- There is some evidence that a gene, ApoE, could be linked to an increased rate of cognitive decline. Study results thus far have been inconsistent, however.