Magnetic resonance imaging (MRI) techniques may detect biomarkers for early diagnosis in patients with amyotrophic lateral sclerosis (ALS), according to a review study titled “The value of magnetic resonance imaging as a biomarker for amyotrophic lateral sclerosis: a systematic review,” published in BMC Neurology.
Biomarkers are measurable substances, such as chemical changes in the blood or changes in tissues, which can be linked to a specific disease. They can also be used to follow the progression of a disease and are important tools to recognize whether a drug is working.
ALS is hard to detect in its early stages and it currently takes about a year to diagnose a person with the disease. In addition, the evaluation of the effectiveness of a treatment is based only on the ALS functional rating scale, different motor tests, and survival time. But these are all late-stage measures.
There is an urgent need for early detection of ALS. A promising approach to search for specific biomarkers and early detection of the illness may be through MRI techniques.
MRI is an umbrella term that includes many different scanning techniques which can be used for studying ALS-related changes in the brain and spinal cord. In this review, researchers went through 116 different MRI studies that investigated ALS patients. The team searched for connections between MRI abnormalities and clinical scores of the ALS functional rating scale.
The most disease-specific changes were atrophy — a breakdown of tissue — in the motor (movement) area of the brain, and especially along the corticospinal tract (CST). The CST is like a neuron pathway that conducts impulses from the brain to the muscles. The patients with more severe atrophy also had more severe clinical symptoms, connecting the MRI findings with the scores of the ALS functional rating scale.
One of the MRI techniques is called functional MRI and measures the level of activity in different parts of the brain. An unusually high level of activity was observed in the motor region of the brain; researchers suggested this over-activity may be an overcompensation for the atrophy and loss of neurons.
In addition, atrophy was also present in the frontal lobes of the brain, which includes the primary motor cortex that regulates voluntary movements like walking. The frontal lobes are also responsible for abilities such as planning, decision-making, attention, and social behavior.
Atrophy in the frontal lobes may lead to frontal lobe dementia (frontotemporal dementia). Recent studies have confirmed that up to 50 percent of ALS patients demonstrate some impairment in cognitive abilities, and around 20 percent meet criteria for full-blown dementia syndrome. Personality changes often happen because of frontal lobe dementia and may include symptoms like increased impulsiveness, apathy, and socially inappropriate behavior.
Although not to the same extent, a wide range of other areas of the brain were also affected in the patients, explaining the many different symptoms presented in people with ALS.
Larger studies are needed to establish the use of MRI, but MRI techniques seem to be a promising tool to detect biomarkers that could be used to speed up ALS diagnosis, allowing people to seek earlier treatment. It could also be valuable in the development of new treatments, according to the researchers.