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Development of a Life Expectancy Calculator for Alzheimer’s & Dementia

Last Updated: May 05, 2020

 

The Short Answer

Prior to the discussion of the development of an Alzheimer’s / dementia Life Expectancy Calculator, let’s address the first question most people have after receiving the diagnosis of an incurable disease: How long do I have left to live? With dementia, the answer differs depending on the type. By far the most common form of dementia is Alzheimer’s disease, and the average life expectancy after diagnosis is 10 years. Other dementias have different life expectancies. Someone with vascular dementia lives for about five years after diagnosis. Someone who has dementia with Lewy bodies will typically live for two to eight more years.

However, everyone with dementia experiences impacts and symptoms differently. People have lived more than 25 years after being diagnosed with Alzheimer’s disease. Factors including underlying health, the severity of early symptoms, and even gender come into play.

But how can a person know how long they have to live when they’re diagnosed with dementia? Is there an Alzheimer’s Life Expectancy Calculator to get as close to a definitive answer as possible? Can artificial intelligence help? And why would they want to know?

 

Why Knowing Life Expectancy is Useful

Knowing what to expect, including life expectancy (even if this is very sad information) helps with planning. Someone predicted to survive for five or six years, as opposed to two years, will want to make more extensive plans, including getting an estate in order, activity planning and budget. Knowing how quickly the disease is expected to progress symptomatically can impact care decisions. For example, if the disease is predicted to come on very quickly, then skipping assisted living and looking into a nursing home might be the best option as it might be less disruptive to the individual.

Knowing when full-time care becomes a requirement, either at-home, or in a memory care residence is especially useful given the high cost of care. It is estimated that 50% of nursing home residents have some level of dementia and over 60% of nursing home residents care is paid for by Medicaid. Medicaid eligibility is complicated, and families can spend up to 5 years waiting for a loved one with dementia to become Medicaid-eligible. Therefore, knowing how soon care is required can make a huge financial difference.

 

Academic Research into Life Expectancy Calculators for Alzheimer’s / Dementias

It turns out that the length of time a person has before needing full-time care, before moving into a care community, and before dying can all be predicted somewhat accurately. It’s important to remember that none of this is definitive, and of course there’s no way to pinpoint exactly how much time a person has left. This information, though, can help families get a general understanding of how to plan for the future and what to expect as the disease progresses.

In a study conducted at the department of neurology in Columbia University, groups of people with mild Alzheimer’s were followed for 10 years, and assessed semiannually. Data from these assessments were plugged into a complicated algorithm. The people studied were tested for the following:
– Mental status (mini-mental status exam) score
– Cognition (thinking ability) and function (physical ability)
– Motor skills
– Psychology and behavior
– Basic demographic information

The model worked. 506 total people were used for this experiment, all with mild dementia at the start, and the predictions were about 95 percent accurate. Researchers could tell when a person with dementia would need full-time care, then when it would be necessary to move into an institution like assisted living with memory care or a nursing home, and ultimately when a person would die.

For example, two 68-year-olds with Alzheimer’s disease recorded mini-mental status exam scores that were in the high 30s on their initial visit, but one patient needed a full-time caregiver and had delusion symptoms while the other was more independent. When these and other data were plugged into the model, different times of death were predicted. The first patient lived less than three years, while the more independent person lived more than 10 years. These outcomes were predicted by researchers in the study and came to be true.

Other experiments have yielded similar results. A University of Kentucky study analyzed the records of more than 1,200 people with dementia and found that it was possible to accurately predict their life expectancy. Researchers looked at many variables including family history and medical problems like high blood pressure and heart disease, and ultimately realized it came down to three things: age when the first symptoms appeared, gender, and how impaired someone was when diagnosis was first made. The models were similar. A woman in her 80s with moderate dementia was expected to live about five years after diagnosis, while a man in his 60s with mild dementia lived around seven more years, according to the study.

Importantly, these are all theoretical, and researchers who found their models to be highly successful still advise that it is impossible to specifically pinpoint when a person will die. In other words, there is no way of getting an exact number, just a rough idea.

Variables Impacting Life Expectancy Calculations

 

Life Expectancy by Stage of the Disease

The average number of years a person lives with Alzheimer’s disease is about 10. Keep in mind, however, that there’s a gap between when symptoms begin, and a diagnosis is actually sought. The first symptoms of Alzheimer’s disease—forgetting names, misplacing items, difficulty concentrating at work or performing simple tasks—arrive an average of almost three years before the diagnosis is made.

The scale most commonly used by health professionals for the stages of dementia is the Global Deterioration Scale (GDS), also called the Reisberg Scale. The table below shows a patient’s average life expectancy by the stage of dementia. These are averages based on studies of large numbers of Alzheimer’s patients.

Life Expectancy By Stage of Alzheimer’s / Dementia (according to the Reisberg / GDS Scale)
Stage Expected Duration of Stage Estimated Life Expectancy (Years Remaining)
Stage 1: No Cognitive Decline N/A N/A
Stage 2: Very Mild Cognitive Decline Unknown More than 10 years
Stage 3: Mild Cognitive Decline Between 2 years and 7 years 10 years
Stage 4: Moderate Cognitive Decline 2 years Between 8 and 3 years
Stage 5: Moderately Severe Cognitive Decline 1.5 years Between 6.5 and 1.5 years
Stage 6: Severe Cognitive Decline 2.5 years 4 years or less
Stage 7: Very Severe Cognitive Decline 1.5 to 2.5 years 2.5 years or less


 

Do Treatments Add Time to Life Expectancy?

Experts simply don’t know whether treatments help a person live longer with Alzheimer’s disease. AD and other similar dementias progress no matter what. Treatments like medications and therapies have been conclusively shown to help manage symptoms, meaning they make it easier to live with the disease, but they do not reverse symptoms. The memory of a person with dementia who takes medications like cholinesterase inhibitors, for example, will be slightly better than the memory of someone who is not on medication. Quality of life therefore improves with treatment. This means better years with dementia, but probably not more years.