Association between Long-Standing Uncontrolled Hypertension and Alzheimer's disease
Hypertension is a medical condition in which the blood pressure in the arteries is persistently elevated.
Hypertension can be primary or secondary(due to some underlying cause).Long-term high blood pressure, however, is a major risk factor for coronary artery disease, stroke, heart failure, atrial fibrillation, peripheral vascular disease, vision loss, chronic kidney disease, and dementia(including Alzheimer’s disease). Increasing evidence also suggests that hypertension is a risk factor for Alzheimer’s disease (AD), highlighting its participation in all major causes of cognitive impairment. High Blood Pressure in the United States:
Having high blood pressure puts a person at risk for heart disease and stroke, which are leading causes of death in the United States. About 75 million American adults (32%) have a high blood pressure—that’s1 in every 3 adults. About1 in 3 American adults have pre-hypertension—blood pressure numbers that are higher than normal—but not yet in the high blood pressure range.
Only about half (54%)of people with high blood pressure have their condition under control. High blood pressure was a primary or contributing cause of death for more than410,000 Americans in 2014—that’s more than1,100 deaths each day. High blood pressure costs the nation$48.6 billion each year. This total includes the cost of health care services, medications to treat high blood pressure, and missed days of work.
There are several types of drugs used to treat high blood pressure, including:
•Angiotensin-converting enzyme (ACE) inhibitors.
•Angiotensin II receptor blockers (ARBs).
•Calcium channel blockers.
Alzheimer's disease(AD), also referred to simply as Alzheimer's, is a chronic neurodegenerative disease that usually starts slowly and worsens over time.
Alzheimer's is the most common form of dementia, a general term for memory loss and other cognitive abilities serious enough to interfere with daily life. Alzheimer's disease accounts for 60 to 80 percent of dementia cases.
Alzheimer's is not a normal part of aging. The greatest known risk factor is increasing age, and the majority of people with Alzheimer's are 65 and older. But Alzheimer's is not just a disease of old age. Approximately 200,000 Americans under the age of 65 have younger-onset Alzheimer’s disease (also known as early-onset Alzheimer’s).The cause of Alzheimer's disease is poorly understood. About 70% of the risk is believed to be genetic with many genes usually involved. Other risk factors include a history of head injuries, depression, or hypertension. The disease process is associated with senile neuritic plaques and neurofibrillary tangles in the brain. A probable diagnosis is based on the history of the illness and cognitive testing with medical imaging and blood tests to rule out other possible causes. Initial symptoms are often mistaken for normal aging. Examination of brain tissue is needed for a definite diagnosis. Mental and physical exercise, and avoiding obesity may decrease the risk of Alzheimer’s Disease; however, evidence to support these recommendations is not strong. There are no medications or supplements that decrease risk. No treatments stop or reverse its progression, though some may temporarily improve symptoms.
In particular, some studies, but not all, have shown that mid life hypertension is a risk factor for the Alzheimer’s Disease. Although the mechanisms of the association remain unclear, there is evidence that hypertension may promote the accumulation and/or aggregation of the Aβ peptide in the brain. Increases in brain amyloid have been reported in ApoE4+ hypertensive individuals, an effect reduced by antihypertensive treatment. The findings raise the possibility that the cerebrovascular dysfunction and damage produced by midlife hypertension impairs the vascular clearance of brain Aβ, resulting in amyloid accumulation in cerebral blood vessels and cognitive dysfunction. Drugs acting on peripheral blood vessels like Nitrates, calcium channel blockers, ACE inhibitors, Diuretics and Hydralazine might be beneficial as they act on peripheral vessels and decrease cerebrovascular insults.
Based on the review of past research studies it is evident that hypertension is a significant risk factor for the later development Alzheimer’s disease. Whatever the mechanisms of the interaction between hypertension and Alzheimer’s disease, the realization that cerebrovascular damage may play a role in Alzheimer’s disease supports the notion that maintaining vascular health by preventing vascular insult and controlling vascular risk factors, such as hypertension, may be an important preventive strategy for late-life dementia and Alzheimer’s disease. Since there is no cure for Alzheimer’s disease and only the progression can be delayed, so the risk factors like hypertension should be treated and long-term effects of uncontrolled hypertension should be avoided.