All diagnosed cases of Alzheimer’s disease are marked by dementia, but not all dementia is caused by Alzheimer’s disease. In fact, there are more than 100 known causes of dementia, defined as “chronic or persistent disorder of the mental processes caused by brain disease or injury and marked by memory disorders, personality changes and impaired reasoning.”
Dementia, therefore, is a syndrome that contains many diseases and conditions, including Alzheimer’s disease, the most common cause of dementia in older adults.
Among the many conditions causing dementia, 5 to 10 percent are treatable and even reversible, says Dr. David Carr, a neurologist specializing in geriatrics and Alzheimer’s disease with Washington University Physicians. For example, some medications can cause cognitive changes, and depression may be linked to forgetfulness. Metabolic disorders, hormonal dysfunction and nutritional deficiencies are other treatable conditions that may cause dementia.
“But 90 to 95 percent of the time, (dementia) is irreversible, and you’re dealing with a neurodegenerative disease,” Carr says, estimating that Alzheimer’s disease is the cause in about 70 percent of those cases. “Probably the second most common cause is Lewy body dementia, which is sort of a cousin to Alzheimer’s disease but typically presents with psychosis—hallucinations or delusions—Parkinson’s-type symptoms and fluctuating mental status.”
Alzheimer's disease, the flagship form of dementia, is the sixth-leading cause of death in the United States, according to the Alzheimer’s Association. “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,” says Jan McGillick, education director for the Alzheimer’s Association St. Louis Chapter.
“Different types of dementia are associated with particular types of brain cell damage in particular regions of the brain,” McGillick says. “For example, in Alzheimer's disease, high levels of certain proteins inside and outside brain cells make it hard for brain cells to stay healthy and to communicate with each other. The brain region called the hippocampus is the center of learning and memory in the brain, and the brain cells in this region are often the first to be damaged. That's why memory loss is often one of the earliest symptoms of Alzheimer's.”
Carr evaluates patients based on physical and cognitive exams, as well as information provided by a family member or ‘good informant’ regarding the patient’s behaviors and cognitive changes. “If you have an informant who notices changes over time, you obtain information about what types of cognitive domains are being affected, which can include memory, attention, visual/spacial skills, ability to plan and organize, and language skills. The second thing we ask about are functional deficits, and the ones we tend to see early affect driving, cooking and handling finances. The third line of questioning has to do with any changes in health, medications, etc.”
Following this thorough investigation, Carr begins to form an opinion regarding the most likely causes of the patient’s dementia. He gathers additional evidence via blood tests, brain scans and biomarker tests. With a working diagnosis, he and the patient embark on a treatment strategy with the hope of slowing or stabilizing the condition.
“While there are medications that may be able to slow the effects of dementia, there is currently no known cure. For that reason, I find that providing education and support for the caregivers is one of the most important tools available for a family experiencing dementia of any kind,” says Erin Rogers, assisted living director for Fountain View at Friendship Village Sunset Hills. “Validation is a very important tool used when working with someone with dementia. It is important to find value and confirmation in stories or thoughts even when they may be outdated or repetitive.”
Carr notes that there is hope based on current research. He and colleagues are studying the relationship between Alzheimer’s disease and insulin resistance, in which too much glucose may penetrate brain cells and affect function. Part of a national research effort known as the ‘SNIFF Study,’ researchers hope to discover whether insulin, administered as a nasal spray, improves memory in adults with a mild memory impairment or Alzheimer’s disease.
Another study involves diagnosing Alzheimer’s disease long before symptoms become apparent. The idea is to identify the telltale proteins present in the brains of Alzheimer’s patients in people with no apparent cognitive decline and begin treatment to delay the disease’s progression.
In the meantime, Carr notes that a healthy lifestyle is considered the best way to reduce dementia risk factors. “It’s not yet proven, but it appears that exercise, good nutrition, stress reduction, social interaction and ongoing mental activity may go a long way to protecting the brain,” he says.