A common link — damage to the white matter of the brain — appeared in all patients with Alzheimer’s disease in a small study published in May in the peer reviewed journal, Radiology.
Researchers studied 28 patients with early onset Alzheimer’s, 12 patients with lvPPA (logopenic variant of primary progressive aphasia) and 13 patients with PCA (posterior cortical atrophy) who were matched with healthy subjects of the same age and sex. Conjunction and interaction analyses were used to define overlapping and syndrome-specific patterns of brain damage. They looked at MRI to identify similarities and differences across the AD spectrum.
Patients with EOAD, lvPPA and PCA shared a common pattern of white matter damage involving the body of the corpus callosum, fornix and main anterior-posterior pathways, and also shared cortical atrophy of the left temporoparietal regions and precuneus, researchers reported in the study.
EOAD patients had specific damage to the genu and splenium of the corpus callosum and parahippocampal tract bilaterally. All AD patients, particularly the lvPPA and PCA participants, showed more severe white matter damage.
“Alzheimer’s is a gray matter disease,” study co-author Federica Agosta, MD, said in a news release from the Radiological Society of North America. “However, white matter damage has a central role in how the disease strikes and progresses. The white matter damage in patients with focal AD syndromes was much more severe and widespread than expected.”
Risk of misdiagnosis
Findings underscore the theory that Alzheimer’s disease may travel along white matter fibers from one area of the brain to another, according to Agosta. “In early onset AD and atypical AD forms, white matter degeneration may be an early marker that precedes gray matter atrophy,” Agosta said.
Researchers stressed the importance of specialized imaging which may help in identifying people with early onset and focal AD before symptoms present. “Because there is not much structural damage in the early stages of focal Alzheimer’s disease, there is a risk that patients may be misdiagnosed and excluded from clinical trials,” Agosta said.
Scientists believe that brain changes begin 10 to 20 years before any clinically detectable signs or symptoms of forgetfulness appear, according to information from the National Institute on Aging website. “That’s why they are increasingly interested in the very early stages of the disease process,” the site reports. They hope to learn more about what happens in the brain that sets a person on the path to developing AD.”
Alzheimer’s disease is the sixth leading cause of death in the U.S., according to the NIA. More than 5 million Americans have Alzheimer’s disease. Those numbers are expected to increase significantly unless the disease can be effectively treated or prevented.