In 2011 there was a new clinical diagnostic criteria for Alzheimer's disease dementia. While the previous guidelines only recognized one stage—Alzheimer’s dementia—the new guidelines propose that Alzheimer’s disease progresses on a continuum with three stages—starting from an early, preclinical stage with no symptoms; to a middle stage of mild cognitive impairment (MCI); and then to a final stage of Alzheimer’s dementia. These new guidelines forge a solid causal link, from disease in the brain that have no symptoms, to dementia. But these guidelines are too crude.
Because some older adults have the disease in the brain but do not show any of the effects, instead of refining the criteria of what is the disease and how it develops, some neurobiologists are arguing that the disease in the brain is what matters. If you have the disease then you are demented. This is a new wave of biological determinism that has not been seen for the past century with passing of eugenics.
Neuroscientists are saying that it does not matter how you express the disease the disease is already there. This is not a strange conclusion if you follow neuroscientists’ logic. But dementia is more than the disease in the brain.
Numerous studies are now showing that even if the brain has the disease it does not dictate the behavior. In the famous, "Nuns Study" David Snowdon first reported this very strange anomaly. He found that a third of the nuns who behaved and acted free from dementia, were found to have the disease of Alzheimer’s during autopsy. Numerous studies have also found this lack of correlation between the disease and the behavior. All these studies erode the direct linear link between the disease and the behavior.
But the strange fact is how many people have early stages of the disease in the first place. In 2011 Heiko Braak and his colleagues from the University of Ulm, in Germany looked at 2,332 brains from various hospitals. The sample was not random, but convenience and included children. This is the first time that children’s brans were studied for dementia. From this study only 10 brains showed a complete lack of disease (less than half one percent). The rest of the sample showed some stages of the disease. This is an important finding. Heiko Braak introduced the classification of Alzheimer’s disease--Braak stages--with a similar classification proposed for Parkinson's disease. The finding show that even young adults as young as twenty start to show the disease and everyone has some disease. Braak and his colleagues have consistently argued that the disease itself is complex, and has a developmental stage. But the new guidelines do not address this subtlety.
The guidelines argue that early stages of the disease will eventually lead to full-blown disease and dementia without any intervening stages. Science is teaching us that there are mediating and moderating factors that the NIA guidelines need to address. Otherwise all our children are already demented and we are just waiting for them to get older in order for the to express this disease.
© USA Copyrighted 2013 Mario D. Garrett