Imaging Biomarkers in Alzheimer
Alzheimer’s disease (AD) is a neurodegenerative disorder considered the most common cause of dementia worldwide. Dementia is a general term for the loss of cognitive functions –memory, thinking or reasoning- and behavioural abilities that affects the daily life of a person. According to the World Alzheimer Report, about 50 million people worldwide suffer from dementia. This number is estimated to be almost doubled every 20 years, reaching 131.5 million patients in 2050. AD is deemed the main form of dementia and contributes to 60-70% of the cases.
In this disorder, the connections between the nerve cells that make up the brain are affected, causing the death of these cells and the loss of brain tissue. In AD, abnormal levels of beta-amyloid and tau proteins are found in the brain. Evidence suggests that a complex interaction between these proteins is the main responsible of Alzheimer’s brain changes. Depending on the brain regions affected, different alterations may be presented in the patient. Some of the first regions to be altered are the entorhinal cortex and hippocampus, which are closely related to memory performance.
AD is a progressive disorder in which more parts of the brain are damaged over time. As this happens, more dementia’s symptoms are developed and the patient’s condition gradually worsens. In the early stages, people often present a reduced ability to take and remember new information; and may be accompanied by word-finding problems, vision or spatial issues, or impairment in reasoning or judgement. As AD progresses, patients suffer an increased memory and cognitive loss. They can experiment difficulties in recognizing family and friends, loss the ability to have conversations or be unable to respond to their environment. In severe cases of AD, brain tissue shrinks significantly, making people unable to communicate and completely dependent on others.
There are no effective treatment options for AD patients able to detain its progression. Nevertheless, symptoms can mitigate by means of medication and a healthy lifestyle. Some risk factors, such as age and genetics, are out of control; while others can be overcome to take care of brain-health. According to the Alzheimer’s Research & Prevention Foundation, regular physical exercise can reduce the risk of developing AD up to 50%. Others such as social engagement, healthy diet, mental work and stimulation, good sleep and stress management has proven to fortify the brain and reduce the risk of suffering any form of dementia.
As shown, prevention is the most effective way to fight this devastating disease. An early diagnosis is fundamental for this purpose. Nowadays, this is performed mainly by means of questions to the patients, blood/urine tests, and memory, attention or problem-solving exercises. Brain scans, such as computed tomography (CT), positron emission tomography (PET), or magnetic resonance imaging (MRI) are also key elements in diagnosis because they allow to detect the presence of abnormal concentrations in proteins and atrophy.
In this way, our team has developed automatic brain tools for the detection and assessment of Alzheimer in a subject. Our Brain Atrophy suite and Voxel-Based Morphometry analysis modules are designed to evaluate the shrinkage of the brain by comparing its volume and morphology with a set of healthy subjects (paired in age and gender).
Above there are two examples of Brain Atrophy: Hippocampal Asymmetry analysis reports over a healthy and over an Alzheimer’s brain. This analysis provides a view of the brain focused on hippocampus’s status (volume and level of asymmetry) framed in a comparison with a set of healthy people. Taking a look at them, relevant differences in the Alzheimer’s brain come to light: the left hippocampus volume falls below the normal ranges (red region in the table), while the left-right hippocampus asymmetry is also presented out of normal values.
Other important tool to assess brain atrophy is our Voxel-Based Morphometry analysis module, which gives volumes and statistical scores comparing morphology differences between the pathological brain and the previous set of healthy subjects.
The analysis above has been performed over the same Alzheimer’s brain than the previous Hippocampal Asymmetry evaluation. Both reports highlight alterations in the hippocampus, which is one of the first affections in AD.
Other tools we have included in the Brain Atrophy suite, such as global brain screening, frontal-temporal dementia and motor cortex evaluation can be also performed to obtain a more enlightening sight of the brain. The combination of these brain assessment tools with traditional AD evaluation methods can lead to a better understanding and an earlier diagnosis of this terrible pathology.