Alzheimer’s Disease Study Finds Critical Differences in Memory Loss Progression Based on Presence of Specific Proteins

A study by Karolinska Institutet, published in the journal Molecular psychiatryoffers new insights into the progression of Alzheimer’s disease (AD). The research reveals critical differences in the progression of memory loss based on the presence of specific proteins in the brain.

Alzheimer’s disease is the most common form of dementia. It is characterized by the accumulation of amyloid beta (Aβ) and tau proteins in the brain, leading to cognitive decline. Traditionally, memory clinics have relied on positron emission tomography (PET) to detect amyloid beta protein accumulation. However, recent advances now allow tau protein accumulation to be detected as well.

The study highlights that people with symptoms of memory loss and high levels of tau protein (tau positivity) also have high levels of Aβ (Aβ positivity). This combination is associated with malignant progression of memory loss due to Alzheimer’s disease. However, people who are Aβ positive but tau negative may experience a more benign progression of symptoms.

“If a person is Aβ positive but tau negative, then the progression of symptoms is likely to be benign. If the symptoms are malignant, it is possible that the cause is not exclusively Alzheimer’s disease, but could also involve other medical conditions that contribute to memory loss. If both Aβ and tau are absent, the cause of memory loss is likely another medical condition rather than Alzheimer’s disease,” says Konstantinos Ioannou, a PhD student in the Department of Neurobiology, Health Sciences and Society.

This distinction is crucial for accurate diagnosis and treatment planning.

The presence of high levels of tau protein is strongly linked to cognitive decline due to Alzheimer’s disease. In people with high levels of Aβ but low levels of tau, memory loss can result from several pathologies. In the era of new drugs that can eliminate Aβ, identifying the root cause of memory loss is essential to determine the most effective treatment for each patient.

“Developing biomarker panels that measure multiple proteins simultaneously will help us understand the complexity of each patient,” says Ioannou, first author of the study. “This approach will allow for more personalized care, tailored to prognosis or treatment of other contributing factors.”

The research team used PET to measure Aβ and tau protein levels, as well as brain function, in both healthy individuals and patients. Statistical modeling was then applied to assess the progression of memory loss in all participants. Finally, the medical histories of patients with different tau protein levels were compared.

In the future, the researchers plan to measure Aβ and tau levels in cerebrospinal fluid and blood samples. This could allow for easier clinical tests to identify people in whom Alzheimer’s disease is the primary cause of memory loss. Additional studies, including MRI scans and brain data from deceased people, are also planned to confirm these results before introducing tau measurement into clinical practice.

This study marks a significant advance in understanding Alzheimer’s disease and improving patient care through more accurate diagnostic tools and personalized treatment plans.