A collaboration of Japanese and Spanish scientists sheds new light on the primary brain alterations induced by Alzheimer’s Disease. The results, recently published in the journal Brain, describe a new series of biomarkers that characterize the initial stages of the disease when no cognitive impairment is yet apparent.
In the case of Alzheimer’s disease, it is known that the first signs of the disease occur around 20-25 years before the appearance of the first cognitive symptoms. These initial alterations consist of abnormal accumulations of a certain type of proteins in the brain (amyloid plaques and neurofibrillary tangles) that are only detectable by highly invasive techniques for the patient, such as lumbar puncture or positron emission tomography scan (PET).
The investigation, framed within a bigger project of the study of the aging sponsored by the Government of Japan, consisted in the analysis of the brain activity at rest of 38 cognitively healthy people and 28 patients with mild cognitive impairment.
In addition to this study and the evaluation of the participants’ cognitive status, all participants underwent MRI and PET scans, so that all of them knew the degree of structural integrity, the level of beta-amyloid plaque accumulation, and the metabolic consumption of their brains.
Based on cognitive status, participants were separated into healthy subjects and patients with mild cognitive impairment (MCI)
The 2 groups were, in turn, split into other 2 categories, depending on the information obtained from the MRI and PET analyzes, namely “Positive” (presented neurobiological abnormalities related to Alzheimer’s disease) and “Negative” (no abnormalities detected).
The results of the analyzes showed that it is possible to distinguish between the 4 groups using only the information obtained from a simple scan. In particular, the electrophysiological activity of the frontal region of the brain was shown to be fundamental when classifying the subjects of the different groups.
Participants with neuropathological abnormalities related to Alzheimer’s Disease showed a greater high-frequency brain oscillatory activity in the frontal region of the brain than those without evidence of these abnormalities.
Additionally, the positive MCI patients, in turn, showed greater oscillatory activity at low frequency than the positive healthy subjects, constituting an increase in a marker of the progression of the Alzheimer’s Disease, according to the researchers.