Alzheimer's Disease Part II: Risks and Contributing Factors

Here's some good news and bad news for a 73-year-old United States citizen. The good news: According to actuary tables you will live to age 85 or older. The bad news: One out of three 85-year-olds have Alzheimer's Disease and the older we get the more likely we will develop Alzheimer's. Age is the greatest risk factor for Alzheimer's:

• An estimated 5.2 million Americans have Alzheimer's Disease.
• 200,000 individuals under age 60 have early onset Alzheimers.
• One in 9 people age 65 and older (11% of the population) have Alzheimer's.
• Of those with Alzheimer's, the vast majority (82%) are age 75 or older.
• The risk for Alzheimer's doubles every five years after age 65.
• Because women live longer, two-thirds of Americans with Alzheimer's are women.

Contributing factors in Alzheimer's Disease:

• Genetic mutation of chromosomes 1, 14, and 21 are associated with early onset Alzheimer's. An individual with a parent with these genetic mutations has a 50% chance of developing early onset Alzheimer's (under age 60). 
• Everyone inherits one form of the APOE gene from each parent. Less that 1% of Alzheimer's cases are due to these APOE genetic factors. 
• The ε3 form, the most common, occurs in 60% of the population and neither increases or decreases the risk for Alzheimer's.  
• Having the rare ε2 form may decrease one’s risk for Alzheimer's. 
• 30% of the population have the ε4 form. This form increases the risk of developing Alzheimer’s disease.  
• The accumulation of beta-amyloid plaques and tau tangles result in a cascade of invents in the brain that eventually kill neurons. Most researchers believe that the accumulation of plaques and tangles are an end-stage of the disease and not the cause of the disease. Nonetheless, the accumulation of this brain "trash" leads to additional brain cell destruction. 
• Immune cells called microglia try to destroy the invasion of plaques. These microglia release prostaglandins, C-reactive proteins and COX-2 enzymes stimulating inflammation that contributes to brain cell death.
• Accumulation of beta-amyloid plaque can damage mitochondria, structures that produce energy for the cells.When mitochondria malfunction they produce an overabundance of molecules called free radicals causing cell destruction.
• Beta-amyloid plaque may cause excessive amounts of calcium to enter neurons killing brain cells.

• Because estrogen protects against Alzheimer's, early menopause and hysterectomy contribute to Alzheimer's. Menopause marks the time for women to consider supplemental estrogen to protect against Alzheimer's, osteoporosis, wrinkles, and dry skin. In most cases the benefits of estrogen outweigh the risks. Those taking estrogens need careful monitoring, of course.
• High caloric intake promotes inflammation.
• "Super-size Me" advocates have an increased risk for Alzheimer's because trans-fats, snack food, and fried foods lower levels of good cholesterol and raise the levels of C-reactive protein, a substance that causes inflammation.
• Emotional stress contributes to the death of neurons in the hippocampus. The hippocampus (the tiny sea-horse shaped organ sitting near the middle of the brain) is the main memory switching station of the brain. After age 45, the hippocampus loses about 6% of its cells every ten years. Emotional stress exacerbate these losses.
• People who are physically inactive are more likely to develop Alzheimer's than those who exercise regularly.
• People with fewer years of education appear to be at higher risk for Alzheimer's. Statistics are misleading, however. One of the brightest professors at Texas A&M had severe life-ending Alzheimer's. We all know highly educated and extremely intelligent people with Alzheimer's.

Next: Treating Alzheimer's disease