Backed by a $60 million national initiative, researchers at the Yale School of Medicine are making strides toward early diagnosis of Alzheimer’s disease.
As a member of the Alzheimer’s Disease Neuroimaging Initiative, Yale researchers, together with scientists in the United States and Canada, are working toward the development of early-diagnosis tests and biomarkers for Alzheimer’s disease and mild cognitive impairment.
“The rate of atrophy is an important factor in these disorders,” said Dr. Christopher van Dyck ’77, leader of the Yale ADNI site. “The hypothesis is that a structural MRI or a PET scan will be a more sensitive measure of cognitive ability and how it deteriorates over time based on the rate of shrinkage.”
Alzheimer’s, a disorder of the brain characterized by progressive deterioration of a person’s memory and daily functions, afflicts about 4.5 million Americans, according to the Alzheimer’s Association. Mild cognitive impairment is referred to as a mild precursor to Alzheimer’s and mainly affects a person’s memory but leaves the rest of general cognitive activity unaffected. There is currently no cure for either of these disorders.
The ADNI is a new consortium of institutions in both the United States and Canada that is creating a database of brain magnetic resonance imaging and positron electron tomography scans of patients with mild Alzheimer’s, mild cognitive impairment and normal cognitive functions. The scanning will measure the rate of atrophy, or shrinkage, of the brain.
The scans could also aid physicians and researchers in detecting Alzheimer’s and mild cognitive impairment in early stages by providing a reference for comparison in future studies. This will consequently lead to earlier diagnoses, van Dyck said. Early detection benefits the patient because most medications used to treat Alzheimer’s and mild cognitive impairment are most effective in the early stages of the disorder, he said.
In a normal person, the rate of atrophy is relatively small compared to a patient with Alzheimer’s. In a patient with Alzheimer’s, there is significant shrinkage of the entire brain and in particular the hippocampus, the brain’s memory center, van Dyck said.
The database will gather about 800 scans and analyze the atrophy of the studied brains in hopes of finding a correlation between the atrophy and the disease’s progression. The researchers aim to provide a database for future trials of experimental treatments, van Dyck said.
“If a pharmaceutical company wants to research their experimental treatment, they can look at the studies and use them in planning their trial by seeing the rate of atrophy — ultimately designing a study with a drug where they could see the best results at a certain level of shrinkage,” van Dyck said.
Yale is one of 50 member sites of the ADNI, which is headed by researchers at the National Institute of Aging and the University of California at San Francisco and the University of California at San Diego.
“The clinical measures that we have been using up until this point to determine the rate of deterioration of cognitive activity can depend on the patient’s level of fatigue or anxiety; with imaging you do not have those variables,” said Leon Thal, the ADNI principal investigator at UCSD.
Currently, neuropsychological assessment is the most widely used instrument for neurocognitive ability and its deterioration. The introduction of imaging analysis used to differentiate which patients with mild cognitive impairment will progress to Alzheimer’s and how far an Alzheimer’s patient has progressed is relatively new.
Within the field of neuropsychology, there is controversy about whether this initiative’s focus on imaging rather than currently used assessments will be effective.
“The way I see it, is that this is not meant to substitute [for] neuropsychological testing, but it should only be additive in terms of identifying who will progress to [Alzheimer’s] and will only be beneficial to the patient,” said Effie Mitsis, a neuropsychologist working with van Dyck.
A secondary goal of the project is to look further into whether there is a biological marker for dementia and cognitive impairment in the brain.