Recently, a National Institute of Health (NIH) scientific advisory panel concluded that there is no proof that anything reduces the risk of Alzheimer's disease (AD). This statement has been widely misunderstood. There is an extensive body of scientific research that has identified many risk factors for AD, and has also shown that reducing these risks is associated with reduced risk for developing AD. This means there is something that reduces the risk for developing AD. It may be the risk factor studied, such as high LDL cholesterol, or it may be something highly associated with the risk factor, such as stroke. The scientific panel correctly pointed out that the causal link between the risk factor and AD has not been established. However, even if one does not know the causal factor associated with an AD risk factor, it is quite possible that modifying the AD risk factor will also modify the causal factor, and reduce AD risk. From this perspective, it makes good sense to identify your AD risk factors and modify them as much as possible through certain life style modifications and/or appropriate medical treatment.
It is important to work with your physician to establish your overall health baseline and to monitor it regularly. This includes an annual health exam plus recommended screenings for at-risk individuals, such as blood pressure, fasting glucose and cholesterol, an eye exam, and annual memory assessment after age 50 years old or younger if cognitive impairment is a concern.
Body fat, or adipose tissue, is the largest gland in the human body. Central, or abdominal obesity, which is measured by the ratio of the circumference of the waist to the hip, is considered to characterize a type of fat that is particularly hazardous as we age. Both weight gain and central obesity after 65 years old increase the risk for Alzheimer's disease (AD) and Vascular Dementia (VD). Obesity also increases the risk for hypertension, coronary heart disease, stroke, gallstones, and kidney stones.
Another measure of body fat is the body mass index, or BMI, which is the body weight divided by the height. Obesity is defined as a BMI greater than 30, and being overweight is defined as a BMI between 25 and 30. During midlife (40 to 64 years old), obesity triples the risk for developing AD in late life (after age 75 years old), and increases risk for developing VD in late life by 5-fold. During midlife, being overweight approximately doubles the risk for developing AD and VD in late life. During late life however, your risk for developing AD and VD increases if BMI drops to less than 20.
Another frequently associated condition with obesity is Metabolic Syndrome, which is a clustering of obesity with other vascular risk factors, including high blood pressure, high cholesterol, and high blood sugar. Metabolic syndrome is a risk factor for Alzheimer's disease, diabetes, stroke, heart disease and high blood pressure.
Stroke increases an individual's risk of developing vascular dementia by 6-10 times, plus increases risk for Alzheimer's disease. Small strokes, which often go unnoticed, begin to accumulate after age 50 years old when there are one or more vascular risk factors are present. These risk factors include high blood pressure, being overweight or obese, diabetes, heart disease, and lack of regular cardiovascular exercise (at least 3 times weekly for long enough to generate a sweat or get short of breath, which is typically 45 minutes). By controlling existing heart diseases and optimizing cardiovascular health, stroke is a preventable disease.
Diabetes increases the risk for stroke, heart disease, and hypertension, all of which increase the risk of vascular dementia (VD). Diabetes also increases the risk for Alzheimer's disease (AD). Proper diabetes treatment that keeps the hemoglobin A1c level below 7% has been shown to prevent diabetes-related cognitive impairment and reduce risks for AD and VD.
Coronary artery disease, valvular heart disease, atrial fibrillation and other arrhythmias, and congestive heart disease are all risk factors for Vascular dementia (VD) and for Alzheimer's disease (AD). Heart disease is often preventable through proper control of risk factors. In individuals with heart disease, it can often be effectively managed. In most individuals, it is possible to eliminate or minimize this risk and reduce the chance of developing AD or VD.
High cholesterol increases the production of beta amyloid, one of the hallmarks of Alzheimer's disease (AD), and doubles the risk for AD. High cholesterol during midlife (40-64 years old) also increases the risk of developing Vascular Dementia, and dementia in general, after about 20 years. The American Heart Association recommends that total cholesterol should be maintained below 200 mg/dL with LDL cholesterol under 100 mg/dL.
| Total Cholesterol | Risk Level |
|---|---|
| Less than 200 mg/dL | Desirable |
| 200-239 mg/dL | Borderline-High Risk |
| 240 mg/dL and over | High Risk |
| LDL Cholesterol | Risk Level |
|---|---|
| Less than 100 mg/dL | Optimal |
| 100 to 129 mg/dL | Near Optimal/ Above Optimal |
| 130 to 159 mg/dL | Borderline High |
| 160 to 189 mg/dL | High |
| 190 mg/dL and above | Very High |
High blood pressure is a major risk factor for Alzheimer's disease (AD) and stroke. High blood pressure during midlife (40-64 years old) increases the risk for developing dementia in general, after several decades. The use of medication to control high blood pressure reduces the risk of developing AD as well as dementia in general, by 8% per year of control with blood pressure medication prior to 75 years old. After 75 years old, these risks are reduced by 4% per year of control with blood pressure medication. The American Heart Association recommends blood pressure to be near 120/80 mmHg.
| Blood Pressure Category | Systolic(mm Hg) | Diastolic(mm Hg) | |
|---|---|---|---|
| Normal | less than 120 | and | less than 80 |
| Pre-hypertension | 120-139 | or | 80-89 |
| High Stage 1 | 140-159 | or | 90-99 |
| High Stage 2 | 160 or higher | or | 100 or higher |
A strong link between serious head injury and future risk of Alzheimer's disease (AD) has been reported. Head injury with loss of consciousness in individuals with a genetic disposition to Alzheimer's disease (the apolipoprotein E4 gene) increases the risk of the disease ten fold. It is important to protect your head by using your seat belt, wearing your helmet when participating in sports, and making homes fall-proof as appropriate.