Alzheimers Home > Are Diabetes and High Blood Pressure Linked to Alzheimer's Disease?
High Blood Pressure
There may also be associations among Alzheimer's disease, high blood pressure (hypertension) that begins in midlife, and other risk factors of stroke. It is known that even in relatively healthy older adults, high blood pressure and other stroke risk factors, such as age, diabetes, and cardiovascular disease, can damage blood vessels in the brain and reduce the brain's oxygen supply. This damage may disrupt nerve cell circuits that are thought to be important to decision-making, memory, and verbal skills. Scientists are studying the connections between Alzheimer's disease and high blood pressure in hopes that knowledge gained will provide new insights into both conditions.
Large-scale population studies show that diabetes is associated with several types of dementia, including Alzheimer's disease and vascular dementia (a type of dementia associated with strokes). These studies have found that Alzheimer's disease and type 2 diabetes share several characteristics, such as:
- Increasing prevalence with age
- Genetic predisposition
- Deposits of damaging amyloid protein (in the brain for Alzheimer's disease; in the pancreas for type 2 diabetes).
Scientists are learning more about the possible relationships between these two diseases. For example, researchers at the Honolulu-Asia Aging Study (a long-term population study of stroke, neurodegenerative diseases, and aging) explored the links between type 2 diabetes, APOE e4, AD, and vascular dementia. They found that study participants with both type 2 diabetes and APOE e4 had a higher risk of AD than participants with neither. They also found that participants with type 2 diabetes and APOE e4 had more plaques and tangles in their brains and had a higher risk of amyloid deposits in the walls of the arteries supplying the brain than participants with neither condition.
Since 1993, scientists have been working with a large group of older priests, nuns, and brothers in an investigation called the Religious Orders Study. This study has provided a wealth of information about many aspects of Alzheimer's disease, including the possible link between diabetes and cognitive decline. In one analysis, researchers examined tests of five "cognitive systems" involved with word and event memory, information-processing speed, and the ability to recognize spatial patterns in more than 800 participants. The researchers found a 65 percent increase in the risk of developing Alzheimer's disease among those with diabetes compared with those who did not have diabetes. They also found that diabetes was related to declines in some cognitive systems but not in others. The findings from these two studies and others have provided important insights into both Alzheimer's disease and diabetes, and lay the groundwork for future research in this area.