Brett Smith for redOrbit.com – Your Universe Online
Two new studies have revealed readily-detectable, early-warning signs of cognitive impairment.
One study from researchers at the University of California, Davis revealed that the degeneration of a small structure deep in the brain called the fornix provides early clues for the future onset of memory loss or dementia. The other study from the University of Toronto in Canada showed a new link between early-onset Parkinson’s disease and a piece of DNA missing on chromosome 22.
In the UC Davis study, researchers recruited over 100 cognitively healthy people with an average age of 73. Participants underwent brain scans using magnetic resonance imaging (MRI) that revealed their brain volumes and integrity. The researchers also administered psychological tests and cognitive assessments to the participants to score their level of mental function. The study volunteers returned for MRIs and cognitive assessment at about one-year intervals.
At the beginning of the study, none of the participants showed signs of mental decline. Over time, about 20 percent began to exhibit symptoms that would eventually lead to a diagnosis of mild cognitive impairment (MCI) or, in a few cases, Alzheimer’s disease.
The researchers found that variables related to the fornix, an organ that ferries messages to and from the hippocampus, are measurable brain factors that precede cognitive deterioration, according to their report in the JAMA journal Neurology.
“Although hippocampal measures have been studied much more deeply in relation to cognitive decline, our direct comparison between fornix and hippocampus measures suggests that fornix properties have a superior ability to identify incipient cognitive decline among healthy individuals,” said study author Evan Fletcher, a project scientist with the UC Davis Alzheimer’s Disease Center.
“We found that if you looked at various brain factors there was one — and only one — that seemed to be predictive of whether a person would have cognitive decline, and that was the degradation of the fornix,” Fletcher said.
In the Parkinson’s-related study, Toronto researchers discovered that people between the ages 35 and 64 who were missing a specific part of chromosome 22 had a higher risk of developing Parkinson’s disease compared to their peers in the general population, according to their report which also appeared in JAMA Neurology.
The genetic omission of about 50 genes from chromosome 22 is associated with a condition called 22q11.2 deletion syndrome. Individuals with this condition may have birth defects, learning difficulties, and potentially develop schizophrenia. The genetic condition occurs in 1 out of every 2,000 to 4,000 births and is thought to be under-diagnosed.
“Our discovery that the 22q11.2 deletion syndrome is associated with Parkinson’s disease is very exciting,” said study author Dr. Anthony Lang, a neurologist from the University of Toronto. “The varying pathology that we found is reminiscent of certain other genetic causes of Parkinson’s disease, and opens new directions to search for novel genes that could cause its more common form.”
“Studies of patients with 22q11.2 deletion syndrome before they ever develop clinical features of Parkinson’s disease may not only provide important information on the effectiveness of screening methods for early detection of the disease, but also allow for future ‘neuroprotective treatments’ to be introduced at the ultimate time when they can have a chance to make an important impact on preventing the disease or slowing its course,” Lang added.
“Most people with 22q11.2 deletion syndrome will not develop Parkinson’s disease,” said co-author Dr. Anne Bassett, a geneticist at the University of Toronto. “But it does occur at a rate higher than in the general population. We will now be on the look-out for this so we can provide the best care for patients.”
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