As we reported here, on October 23rd Supreme Court Justice Sandra Day O’Connor shared that she’s been diagnosed with the beginning stages of dementia, “probably Alzheimer’s disease.” Alzheimer’s disease is a form of dementia, and the most common. But, her news got us thinking, how does the medical field distinguish between Alzheimer’s and other forms of dementia?
Dementia is the umbrella term that’s used to describe any condition that’s linked to the loss of cognitive function — the big three being thinking, remembering and reasoning — that have an impact on daily functioning.
The hard truth is that as we age, all of us lose brain cells and neurons. But someone with dementia loses many more neurons and — this is key — connections to the neurons that enable signals to travel through the brain. Dependent on the stage of dementia, the cell loss can affect memory, language, visual perception, problem-solving skills, self-management and attention.
According to the Alzheimer’s Association, the first signs of Alzheimer’s disease are short-term memory impairment, which includes (for example) difficulty recalling recent conversations, events and people’s names. Other early symptoms can include aphasia, (trouble finding the right words during conversations) and reduced problem-solving abilities. Loss of interest in activities that previously brought pleasure and an overall sense of depression are also common.
As the disease progresses, people can develop difficulty communicating, get lost in familiar places and undergo behavioral changes, hallmarked by agitation, irritability, hallucinations and delusions. During the latter stage of the disease, affected individuals will have trouble with self-care, such as feeding, bathing and dressing themselves. Walking can even become a challenge.
Most of these symptoms are similar to other types of dementia and it can be difficult to determine what differentiates them all. The key lies in the actual physiology of the brain. The calling card of Alzheimer’s disease is an increase in the amyloid protein in the brain. These proteins build up and clump together forming amyloid plaques that impedes neuron function. Additionally, in Alzheimer’s disease another protein called tau builds up. Both of these protein accumulations in the brain result in brain cell death.
Interestingly, the only truly unique element of Alzheimer’s disease is the presence of amyloid plaques. Tau buildup and neurodegeneration occur in other forms of dementia. According to the Alzheimer’s Association, this can make it challenging (but not impossible) to determine what type of dementia someone has based purely on cognitive testing and symptoms.
As a matter of fact, according to an article in Live Science, a number of people who receive an Alzheimer’s diagnosis don’t actually have the disease. And to complicate matters further, there are few cases of absolute Alzheimer’s disease or other forms of dementia. More often than not, individuals suffer from a combination of dementias, including vascular dementia, which affects the brain’s blood vessels, and Lewy body dementia, which is defined by another type of protein, alpha-synuclein, in the brain.
This is why, as we’ve reported here, there is a strong push to diagnose dementia using biomarkers. A biomarker is a measurable substance, such as an increase in amyloid plaques, whose presence indicates disease. We’ve learned that some of these biomarkers appear as soon as 10 to 20 years before the first symptoms of dementia appear.
When the right diagnosis is made it enables doctors to determine exactly what’s going on in the brain so they can order specific treatments for the disease. Earlier, more accurate diagnoses can result in a better quality of life for those suffering from dementia.
Sources:
https://www.livescience.com/63902-sandra-day-oconnor-alzheimers-dementia-difference.html