Scientists have discovered Alzheimer's in young people, decades before the onset of symptoms.
Two new studies by scientists at the Banner Alzheimer's Institute in Arizona showed that a gene mutation found in young adults was a reliable predictor of the disease.
The first study looked at 44 young adults between 18 and 26.
Nearly half had a gene called presenilin 1 (PSEN1), which is known to cause Alzheimer's, yet none of the participants had any signs of the disease during the study, said the BBC.
The researchers found that those with the mutation had a different brain structure than those without.
In particular, those with the gene had less gray matter in certain brain regions.
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"These findings suggest that brain changes begin many years before the clinical onset of Alzheimer's disease, and even before the onset of amyloid plaque deposition," study author Eric Reiman, in a press release, according to HealthDay.
"They raise new questions about the earliest brain changes involved in the predisposition to Alzheimer's and the extent to which they could be targeted by future prevention therapies."
The studies are a breakthrough in showing that Alzheimer's is a disease that begins to develop far earlier than believed.
The research also shows that it can be tracked through time.
The findings were published in the journal The Lancet Neurology.