(LifeWire) - Doctors often recommend magnetic resonance imaging (MRI) when investigating whether a person has Alzheimer's disease, mainly to rule out other possible causes for cognitive impairment, such as a brain tumor or blood clot. But recent research suggests that MRI could become a key diagnostic tool by revealing changes in the brain even before Alzheimer's symptoms appear.
A painless, outpatient procedure involving a tube-like machine, MRI gives a detailed picture of internal organs, including the brain. For patients prone to claustrophobia, an open MRI can be requested, in which the tube has a window.
Current MRI Diagnostic Methods
A physician will likely schedule an MRI if a patient has symptoms commonly associated with Alzheimer's disease, such as memory loss, confusion and problems with executive functioning. For now, MRI is used to determine if a tumor or clot could be causing the symptoms.
Physicians do not use MRI to predict who will develop Alzheimer's disease. However, they do use it to assist in the diagnosis of Alzheimer's by evaluating for particular patterns of brain atrophy that occur in patients with the disease.
Studying the Hippocampus
Alzheimer's disease affects the brain in many ways, but one of the most apparent involves an area called the hippocampus. This part of the brain is responsible for memory and processing emotion; it also plays a role in an individual's motor skills.
In a small 2008 French study, researchers using MRI to evaluate people with Alzheimer's disease found that the hippocampus in those already diagnosed was nearly a third smaller than average. The hippocampus was 19% smaller in people who had not been diagnosed but were experiencing mental impairment.
The Future of MRI
Researchers who are studying MRI as a diagnostic tool for Alzheimer's disease say the technique is promising, although there are no guidelines or recommendations yet for its use.
In the above mentioned study, which involved 74 subjects, physicians reported being able to classify those with Alzheimer's disease and those without symptoms with 84% accuracy based on measurement of the hippocampus. The researchers were accurate 73% of the time when distinguishing between patients without symptoms and those with mild cognitive impairment. Again, however, it's important to remember that this was a small study.
A 2000 American study had more dramatic results. Researchers looked at MRI results for 119 patients with varying degrees of cognitive impairment. Some patients were normal, some had cognitive impairment at the time of the MRI, and others were already diagnosed with Alzheimer's disease. The researchers (who did not have access to the patients' files) were 100% accurate when determining which patients had been diagnosed with Alzheimer's disease and which had no symptoms. The study reported a 93% accuracy rate when researchers were asked to distinguish between patients with no symptoms and patients who had only mild cognitive impairment, but were not yet diagnosed with Alzheimer's disease.
Not only is MRI promising as a diagnostic tool, but there is hope that MRI will also lead to advances in treatment. If MRI can identify individuals who are at high risk for developing the disease, new treatments might be able to hinder or even stop its progression.More Information About Alzheimer's Diagnosis:
- Imaging Procedures Used in the Evaluation of Alzheimer's Disease
- Neuropsychological Tests for Alzheimer's Disease
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