There’s been a lot of talk over the last month or two about Alzheimer’s disease (AD). The discussion is about genetic predispositions and early diagnosis. This discussion is warranted; however it is important to know that Alzheimer’s disease is NOT a part of normal aging.
It is known that apolipoprotein E (ApoE) gene variation is associated with a greater risk of Alzheimer’s disease; however, a couple of thought come to mind. First, would you want to know? Second, would you live any differently? Although the answers are unique to the individual, the story about genetic predisposition is not. Genetics may have up to a 33% influence on the outcome, except in the case of familiar hypercholesterolemia. In that case if the genetic manifestation is on both sides of the family, the likelihood in offspring is extremely high. However, most chronic conditions such as heart disease, diabetes and high blood pressure the genetics may have up to 30% of the influence on disease manifestation. That means that the individual has 70% control over whether the chronic condition manifests. I view genetic predisposition like a plant. If you put the plant in good soil, water it and giving the right amount of light; it should grow. To create a good environment for heart disease seed: have a sedentary lifestyle, eat a diet high in calories and saturated fats and fail to manage your stress. Then you are likely to get heart disease. To create a poor environment for the heart disease seed: exercise daily, maintain a normal weight, consume a diet high in fiber and low in saturated fats. That’s a recipe for keeping heart disease at bay. Despite the influence of genetics, it may be more important to assume that most chronic disease are interrelated and are greatly influenced by environmental factors. That is what you can control.
What are the factors that influence Alzheimer’s? Alzheimer’s is characterized by the accumulation of beta amyloid plaques and neurofibulary tangles. It manifest initially as mild impairment in short term memory and progresses to more serious cognitive changes, many in multiple domains leaving the individual with difficulties with speech, memory, orientation, learning, comprehension, judgment and the inability to perform normal activities of daily living. I’d like to propose the idea that AD is in someway related to other chronic conditions that are inflammatory in nature. Keep in mind that the same blood that oxygenates your heart, muskuloskeletal system, digestive system, and all other organ systems also nourishes your central nervous system (CNS), your brain. That would mean that if inflammatory proteins are transported via the bloodstream, they are transported to the CNS.
With all of that said, there is a recently finding of a rare type of Alzheimer’s that effects only about 2% of the population. It is referred to as Familial Alzheimer’s disease (FAD). FAD is early onset meaning that it presents before the age of 65, and is inherited. All offspring of an individual with FAD have a 50/50 chance of having it. Individuals with FAD have elevated beta amyloid plaques (AB42 protein), elevated tau and p-tau 181 proteins prior to the appearance of symptoms of dementia.
Over the last 20 years much research has been performed to illuminate this debilitating disease, their is still so much to learn about AD. There are some modifiable risk factors that show an association with AD. Diabetes, high cholesterol in midlife, low levels of physical activity, depression are associated with a greater risk of cognitive decline. Whereas a diet high in fruit and vegetable consumption, low in saturated fats, moderate alcohol consumption, higher levels of educational attainment, ability to speak more than 2 languages and a high level of physical activity seems to offer a protective effect from AD.
So what to do to lessen the likelihood of having AD? Living a lifestyle that will prevent the most common chronic diseases and engaging in activities that enrich your mind should be protective. Engaging in regular physical activity reduces the production of the precursor protein, naprilysin, to beta amyloid plaques. It is also recommended that the type of exercise be varied. It challenges the neuromuscular system and the CNS. Chronic volumes of physical activity attenuate the neural response to stress. Learning something new is good for the CNS as well. Engaging in hobbies or learning activities that are not part of your cerebral repertoire increase spatial memory, increase hippocampal neuronal development and increase neurotropin production. To get the best protection, combine cognitive and physical activities as they each provide distinct benefits to the aging CNS.
Early diagnosis? In the August 2010 issue of the Archives of Neurology three biomarker were present in cerebrospinal fluid (csf) of 90% of the patients with AD and in more than 1/3 of normal adults. The three biomarkers are beta amyloid protein, tau protein and p-tau 181. These findings should influence the search for new treatments and a cure for AD. Of the 5 medications that are currently used to treat AD, none of them target the pathways that produce the beta amyloid, tau or p-tau 181 proteins. Furthermore, these medications are only effective for 6-12 months. There is no cure for AD.
So for now, keep in mind that AD is NOT a normal part of aging and that maintaining overall general health and creating a lifestyle that promotes wellness is probably the best defense against any chronic disease, including AD.