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Trends in brain imaging to help Alzheimer's

It seems like everyone in America knows or will know someone with a form of dementia at some point in their lives. If it doesn't affect them or their families directly, it could affect one of their friends. Dementia refers to a decline in mental ability severe enough to interfere with daily life.1

What are dementia and Alzheimer's disease?

Dementia is not a normal part of aging, though some people incorrectly refer to it as senility. Some common symptoms of dementia include issues with memory, communication, language, focus, attention, reasoning, judgment and visual perception.1 This is caused by damage to brain cells and their ability to communicate with each other. Doctors diagnose certain types of dementia based on medical history, physical examination, lab tests and symptoms.

One form of dementia, Alzheimer's disease (AD), makes up roughly 60-80% of dementia cases.2 AD symptoms typically develop slowly and gradually worsen. The greatest risk factor for developing AD is age. In fact, most of the people with Alzheimer's are over the age of 65. Roughly 200,000 Americans under the age of 65 have younger-onset AD (also referred to as early-onset AD). Some treatments for Alzheimer's may slow the disease, though treatment cannot stop it ompletely.

With Alzheimer's, some people lose the ability to remember important aspects of their lives, such as family members.2 These memory issues may begin with more recent memories, such as those of grandchildren, before progressing to older memories, such as children and spouses. Alzheimer's can also lead to disorientation and mood or behavior changes.

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How can magnetic resonance imaging help?

Magnetic resonance imaging (MRI) produces images of the inside of the patient's body. The scanner contains a super-conducting magnet. Because this magnetic is so powerful, it alters the magnetic field within the vicinity of the scanner. Patients are positioned on the patient table, which is a sliding platform. This moves in and out of the bore, the large hole in the donut shaped scanner.

Throughout the scan, the computer uses pulse sequences, which excite and relax the protons in a patient's body. When this happens, the patient's body emits signals that are picked up by coils. These coils are placed near the patient's body and are sometimes rigid and sometimes flexible. In the case of neuroimaging, the coil is often designed in a way that will keep the patient's head still. Head coils are sometimes called bird-cage coils due to their appearance.

Recent studies have begun to study the brain before dementia and Alzheimer's. One retrospective study claims that MRI scans could predict with 89% accuracy who would go on to develop dementia within three years.3,4 This could be possible up to three years before memory loss begins. Alzheimer's patients develop plaques of Alzheimer's proteins in the brain which are visible on PET scans. However, diffusion tensor imaging (DTI) is an MRI technique that could be particularly helpful in Alzheimer's research.

DTI uses the Brownian motion (random movement of water molecules) to monitor the contents of the brain and assess the health of the brain's white matter. This technique shows where water is allowing for physicians to see what a patient's brain tissue looks like. In the study, people who had cognitive decline showed more signs of damage to their white matter.3,4 This was done with a smaller group of 20 people, 10 healthy and 10 with cognitive decline, and then repeated in a group of 61 people. The accuracy jumped from 89% to 95% when researchers focused on specified parts of the brain which are likely to show damage.3,4

Another group of researchers retrospectively segmented 5074 brain images and monitored for changes in structure volumes at 1 and 2 years.5 The biomarkers they discovered could potentially help with deeper analysis and may influence other imaging studies. The areas monitored were the hippocampus, amygdala, inferior lateral ventricle and lateral ventricle with the counterparts on the left and right sides analyzed separately.

Both of these studies have the potential to lead to important discoveries regarding the progression of Alzheimer's disease. The earlier Alzheimer's can be caught, the better the chance of slowing disease progression. However, it is important to remember that these are both still being researched. This research could help scientists to understand the changes to brain structure that so many Americans face.

References

1. "What Is Dementia?" Alz.org. Web. 30 May 2019. <https://www.alz.org/alzheimers-dementia/what-is-dementia>.

2. "What Is Alzheimer's?" Alz.org. Web. 30 May 2019. <https://www.alz.org/alzheimers-dementia/what-is-alzheimers>.

3. Tamara Bhandari. "MRI Scans May Offer a Way to Predict Dementia Risk." Futurity.org. 28 November 2018. Web. 30 May 2019. <https://www.futurity.org/dementia-alzheimers-disease-mri-scans-1918082-2/>.

4. Jessica Miley. "New Study Uses MRI Scans to Predict Alzheimer's and Dementia: A team of researchers have developed methods to use the common technology to create highly accurate predictive tests." InterestingEngineering.com. 27 November 2018. Web. 30 May 2019. <https://interestingengineering.com/new-study-uses-mri-scans-to-predict-alzheimers-and-dementia>.

5. Christian Ledig, et al. "Structural brain imaging in Alzheimer's disease and mild cognitive impairment: biomarker analysis and shared morphometry database." Scientific Reports. 2018; 8: 11258. Web. 30 May 2019. <https://www.nature.com/articles/s41598-018-29295-9>.