Researchers are exploring the possibility that some cases of Alzheimer’s disease may involve an infectious process, like that seen in Creutzfeldt-Jakob disease and mad cow. Results of an animal study conducted at The University of Texas Health Science Center at Houston indicated that Alzheimer’s disease may spread like an infection.
How is Alzheimer’s like mad cow?
The most common explanation of Alzheimer’s disease is that it involves the accumulation of beta amyloid (or amyloid-beta), which is a protein fragment from an amyloid precursor protein. In a healthy brain, these fragments are eliminated, but in Alzheimer’s disease, the fragments build up, become misfolded and misshapen, and form hard plaques that kill neurons.
Thus far, however, experts have not definitively identified what triggers the accumulation of beta amyloid. In this study, researchers injected brain tissue from an Alzheimer’s patient into mice and compared their findings with those from injected tissue of a healthy control.
According to Claudio Soto, PhD, professor of neurology at The University, “The mouse developed Alzheimer’s over time and it spread to other portions of the brain.” While all of the mice injected with Alzheimer’s tissue developed plaques and other signs of the disease, none of the mice injected with the control tissue showed any indications of Alzheimer’s.
Soto explained that “our findings open the possibility that some of the sporadic Alzheimer’s cases may arise from an infectious process, which occurs with other neurological diseases such as mad cow and its human form, Creutzfeldt-Jakob disease.”
Ninety percent of Alzheimer’s disease cases are sporadic and, like all cases of the disease, there is no cure. The Alzheimer’s Association reports that while 5.4 million Americans are living with the disease today, up to 16 million will be affected by 2050. One in 8 Americans aged 65 and older has Alzheimer’s, and nearly 50% of those aged 85 and older have the disease.
The need for a better understanding of the causes of Alzheimer’s disease is critical if a cure is to be found. Evidence that Alzheimer’s could spread like an infection provides researchers with an avenue for further exploration. Soto noted that “we are currently working on whether disease transmission can happen in real life under more natural routes of exposure.”
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