Pat Summitt did not have a standard version of Alzheimer's. She had early on-set. Early on-set is the description used when a person is diagnoses at an unusually young age. The cut-off is 65. If you're diagnosed at 70 or 80, it is regular Alzheimer's. If you're diagnosed at 30, 40, 50 or even 64, you've got early on-set. Pat passed at age 64, having been diagnosed at 59. Terry Pratchett was diagnosed in late 2007 and passed in early 2015. He passed at 66 after diagnosis around 58.
There's a perception that early on-set progresses much more quickly. However, the Mayo Clinic is now saying that perception is not really backed up by hard facts. The belief is that early on-set patients only live for 7 to 10 years after diagnosis. It is hard to validate these numbers because Alzheimer's is under reported as a cause of death. Additionally, we may not be getting early enough diagnosis of the condition because people are able to cover for some of their forgetfulness and the rest of us can enable them to do so very easily. When an elderly person starts showing signs that dementia may be in play, we kind of expect it and explain it as a result of their age. When a younger person starts demonstrating dementia symptoms, we may find other reasons and overlook the true problem. For example, the person may be diagnosed as having had a minor stroke or struggling with depression or an imbalance with their thyroid. Early on-set is relatively rare. Only about 5% of Alzheimer's patients have early on-set. So, if there are 4Million with Alzheimer's in the US, only about 200,000 will have early on-set.
Another thing to keep in mind is that a person's symptoms are just an outward expression of the disease. We have no idea when the deterioration in the brain really began. We don't know just how advanced the disease is when the person receives their diagnosis. While the disease can progress at a different pace for one person than another, that too may be a perception because we have not tried to identify two or more people who have developed the disease at the same time and are at the same stage for us to compare. So, in Pat's case, she may have been finding memory workarounds for a decade before her diagnosis.
Changes in a person's abilities can be dramatic from year to year. There are times when I think that Lyn's had her diagnosis for 5 years now and she should be further along in the progression of her disease. The reality is that we may have just caught hers particularly early and we may have more years with her than the expected 7 to 10. When we look back over the course of the year, we can see significant changes but there are more yet to come.
Here's an example of a woman with early on-set Alzheimer's. We don't know how long she's been symptomatic but I found the clip interesting because they're trying to highlight the difference a year can make in this disease.
Ultimately, early on-set and regular on-set Alzheimer's destroy the brain. While you can argue it is a disease of forgetting, it's more than that. There is cell death and as much as 100 grams of brain tissue dies. While the person may seem physically healthy and just dealing with memory issues, the body is actually "forgetting" how to heal, how to function, digest, breathe, and so on. If the person gets ill, you can see a sudden intensification of the disease because the body no longer knows how to bounce back.