Alzheimer’s disease is a neurological disorder in which the death of brain cells causes memory loss and cognitive decline. A neurodegenerative type of dementia, the disease starts mild and gets progressively worse. Alzheimer’s is the most common form of dementia, a general term for memory loss and other intellectual 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, although 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. Up to 5 percent of people with the disease have early onset Alzheimer’s (also known as younger-onset), which often appears when someone is in their 40s or 50s. Alzheimer’s worsens over time. Alzheimer’s is a progressive disease, where dementia symptoms gradually worsen over a number of years.
In its early stages, memory loss is mild, but with late-stage Alzheimer’s, individuals lose the ability to carry on a conversation and respond to their environment.
Alzheimer’s is the sixth leading cause of death in the United States. Those with Alzheimer’s live an average of eight years after their symptoms become noticeable to others, but survival can range from four to 20 years, depending on age and other health conditions. People with Alzheimer disease also develop deposits of stuff (protein and fiber) that prevent the cells from working properly. When this happens, the cells can’t send the right signals to other parts of the brain.
Over time, brain cells affected by Alzheimer disease also begin to shrink and die. Lots of research is being done to find out more about the causes of Alzheimer disease.
There is no one reason why people get Alzheimer disease. Older people are more likely to get it, and the risk gets greater the older the person gets. For instance, the risk is higher for someone who is 85 than it is for someone who is 65. And women are more likely to get it than men. Researchers also think genes handed down from family members can make a person more likely to get Alzheimer disease. But that doesn’t mean everyone related to someone who has it will get the disease. Other factors, combined with genes, may make it more likely that someone will get the disease. Some of them are high blood pressure, high cholesterol, Down syndrome, or having a head injury. ‘