A new report published by Greater Boston Physicians for Social Responsibility (GBPSR) and the Science and Environmental Health Network (SEHN) says making healthy lifestyle choices and reducing exposure to multiple environmental toxins may dramatically reduce your risk for Alzheimer’s and other diseases. The report details how these factors can interact with your genes over your lifetime and have a strong effect on how well your brain functions.
The authors of the report make the case that neurodegenerative diseases such as Alzheimer’s and Parkinson’s have multiple causes, and government and individuals should work to eliminate as many of those causes as possible. This is a very different approach to prevention than the drug development discussed by the Alzheimer’s Study Group [see Part 1 of this series].
“Many medical and public health planners are putting their hopes in silver bullet pharmaceutical interventions to slow or treat diseases of aging like Alzheimer’s disease,” the report’s authors write. But recent scientific developments make it look unlikely that new drugs will be effective, they say, and there’s now enough data to make recommendations for prevention.
“Major advances in the understanding of inflammation, oxidative stress and insulin action have occurred over the past decade,” says Jill Stein, MD, one of the primary authors of the report. Dr. Stein is a Harvard Medical School graduate, a board-certified internist and founder of the Massachusetts Coalition for Healthy Communities. “Understanding these processes at the level of cell signaling – the chemical cascades that comprise cellular activity – has allowed us to see some of the ways these processes are inter-related, which we describe in our report as a unifying inflammatory-metabolic framework. This framework enables us to understand how these processes affect each other, and how they are affected by various environmental conditions – including nutrition, exercise, chemical exposures and stress.”
“This inflammatory-metabolic framework also helps us understand the long-observed clustering of common chronic diseases – including diabetes, obesity and vascular disease – within individuals and populations,” she explains. “The shared cellular mechanisms help explain why these diseases are linked to each other, to Alzheimer's disease and to Western lifestyle. It also helps explain why diet, exercise and environmental chemicals can affect disease patterns.” So if we have a better understanding of inflammation, oxidative stress and insulin action, why can’t we just incorporate that understanding in trials of drugs for Alzheimer’s prevention? Given the complexity of Alzheimer’s disease and the likelihood of multiple causes, this approach is just too simple, the report suggests.
“A broad body of evidence suggests that what has conventionally been called Alzheimer's disease is actually a spectrum of disease conditions,” says Dr. Stein, “as well as one end on a continuum of severity. Further, these conditions have a wide assortment of contributing causes that interact in complex ways over the life span.” She and her colleagues don’t think we’re likely to learn anything from the kind of massive prevention studies envisioned by some researchers.
“The many factors affecting Alzheimer’s disease greatly complicates research,” she says. “Key pathological processes implicated in Alzheimer’s – inflammation, oxidative stress and insulin signaling – are affected by a host of covariates including social, educational, nutritional, toxicologic, exercise and genetic factors as well as depression, obesity and disease states (including diabetes and prediabetes, hypertension, and elevated blood lipids). The need to measure and control covariates and effect modifiers is amply demonstrated as a basic principle of epidemiology. Yet few of these established risk factors for Alzheimer’s disease are routinely assessed in research. For all these reasons, meaningful studies are difficult to design, and challenging and expensive to conduct.”
So, if Dr. Stein and her colleagues are right, and new Alzheimer’s prevention studies are not successful, what should we do to prevent the predicted “tsunami” of new Alzheimer’s cases?
“There is substantial encouraging research already in hand,” says Dr. Stein. “A considerable body of animal and human evidence indicates that key pathological drivers of Alzheimer’s – including oxidative stress, disrupted insulin signaling, and inflammation (which are all inter-related) – can often be avoided or reduced, even once in process. This kind of prevention need not involve the expense and virtually inevitable risks of pharmaceuticals. The prevention here consists of reducing a number of inflammatory factors that have become everyday features of modern life – namely common dietary patterns, sedentary lifestyle, and chemical exposures.”
Which of these factors appear to contribute to Alzheimer’s? The Environmental Threats to Healthy Aging report reviews in detail evidence on the following factors:
- metals such as lead, aluminum, iron, copper and zinc
- air pollution
- industrial chemicals and pesticides
- electromagnetic fields
- western diets, which are linked to diabetes and heart disease
- social, mental and physical activity
- education and socioeconomic status.
Like the Alzheimer’s Study Group (ASG), this report proposes changes in government structure and policies. But while the ASG focuses on developing and commercializing drugs, GBPSR and SEHN focus on creating a healthier environment. They recommend changes in farm subsidy policies, pesticide regulations and air pollution control. They believe governments should promote walking and bicycling, discourage driving, and make sure everyone has access to healthy food and good health care. They point out that their recommendations would promote healthy aging in general, not just prevent Alzheimer’s and Parkinson’s.
The Alzheimer’s Study Group (ASG) draft proposals [see Part 1 of this series] and the GBPSR/SEHN report stem from different philosophies about Alzheimer’s prevention and about science in general. Input from Alzheimer’s experts to the ASG have emphasized marshalling the resources to conduct large prevention studies and to bring new drugs to market. The members of GBPSR and SEHN, who plan to submit their report as additional input to the ASG, think a different approach is needed.
“The reductionist traditions of modern science, which tend to focus on single factors, are poorly suited to the complexities of dementia. Addressing broader patterns of risk – rather than single factors such as pharmaceuticals or dietary supplements – may prove more fruitful in understanding and ultimately preventing Alzheimer’s disease,” says Dr. Stein.
Note: Besides proposing changes in government, the Healthy Aging report lists actions you can take to reduce your family’s risk of Alzheimer’s and other diseases [see Part 3 of this series].