Alzheimer's and Dementia

How Do MRIs Help with Neurodegenerative Diseases?

Neurodegenerative diseases like Alzheimer's affect millions of people worldwide. According to data from Alzheimer’s Disease International, over 55 million people are affected by Alzheimer’s alone, with this number continuing to rise. In Switzerland, approximately 153,000 people currently live with a form of dementia, while Huntington's disease affects about 5 to 10 per 100,000 people in Europe.

But what exactly characterizes neurodegenerative diseases, and why are MRI scans crucial for their diagnosis? Below, we take a closer look at these questions.

What Are Neurodegenerative Diseases?

"Neurodegenerative" combines the Greek prefix néuro- (meaning "nerve") and the Latin dēgenerāre (meaning "to degenerate" or "to deteriorate").

Neurodegenerative diseases, therefore, are conditions marked by the progressive loss of nerve cells (neurons) in the brain and/or spinal cord (neurodegeneration). These diseases are primarily characterized by the death of brain cells, leading to brain volume loss or brain atrophy.

The cell loss mainly results in a decline in cognitive abilities and motor functions, leading to cognitive and motor impairments. In most neurodegenerative diseases, these impairments eventually lead to a need for assistance and care; in some, the progressive loss of muscle control can be fatal.

Below is a brief overview of neurodegenerative diseases that can be detected early with MRI:

• Alzheimer’s Disease: Accounting for 60 to 80% of dementia cases, Alzheimer’s is primarily characterized by memory loss, confusion, and behavioral changes, making it by far the most common neurodegenerative disease.
• Frontotemporal Dementia (FTD): FTD mainly affects the frontal and temporal lobes of the brain, leading to behavioral changes, language problems, and memory loss. About 6% of dementia cases are FTD, which affects over 9,000 people in Switzerland.

While there is currently no cure for neurodegenerative diseases, various therapies and treatments can relieve symptoms and slow disease progression. Early diagnosis is essential, and the process is best illustrated through the example of the most common neurodegenerative disease, Alzheimer’s.

Alzheimer’s Dementia

The most common neurodegenerative disease by far, as well as the most prevalent form of dementia, is Alzheimer’s disease.

Causes

The causes of Alzheimer’s, as with all neurodegenerative diseases, are typically complex and include genetic, environmental, and other factors. Alzheimer’s is particularly marked by deposits of pathological beta-amyloid proteins (known as plaques) and tau protein in the brain. These plaques are partially considered a trigger for neuronal degeneration processes.

If you’d like to know more about the causes of Alzheimer’s and other forms of dementia, we recommend our detailed article on this topic.

Diagnosis

The diagnosis of Alzheimer’s disease involves a combination of medical history interviews, neurological exams, cognitive tests, laboratory tests, and imaging techniques like magnetic resonance imaging (MRI).

Standardized tests measure the extent of cognitive impairments, while imaging techniques like MRI reveal structural and functional changes in the brain. Blood tests and cerebrospinal fluid analyses help rule out other possible causes and identify Alzheimer’s-specific biomarkers.

MRI plays a crucial role in the diagnostic process and is essential for early diagnosis. The sooner treatment can begin, the more effectively the progression of Alzheimer’s can be slowed. Below, we’ve outlined this progression to show why early intervention is so vital to the quality of life for those affected.

Progression

Early Stage Initially, affected individuals experience increasing forgetfulness, especially of recent events. Confusion, difficulties with orientation, and initial struggles with daily tasks emerge. Mood swings, mild irritability, or depression can also be early signs of Alzheimer’s.

Middle Stage In this stage, important personal information and the names of close individuals are often forgotten. Communication issues and difficulty with daily activities increase, making assistance more frequently necessary. Mood and personality changes intensify, with common symptoms including aggression, restlessness, and occasional hallucinations.

Late Stage Memory loss now extends to long-term memories, and close family members are rarely recognized. Communication becomes extremely limited, and everyday tasks are mostly manageable only with external support. Personality changes and behavioral disturbances are typically seen as highly severe by close family members.

End Stage In the final stage, individuals are fully dependent on care and lose mobility. They become susceptible to infections and other health complications. Drowsiness and loss of consciousness often occur before the disease ultimately leads to death, usually due to complications (e.g., infections).

Treatment

Since Alzheimer's is unfortunately not yet curable, current therapeutic approaches focus on improving patients' quality of life and slowing the progression of the disease. This involves a combination of medicinal and non-medicinal treatments:

Medication-Based Treatment

Currently, there are mainly two approaches:

• Cholinesterase Inhibitors These medications increase the concentration of the neurotransmitter acetylcholine in the brain, which can improve communication between nerve cells. They are often prescribed in the early to middle stages of the disease.
• NMDA Receptor Antagonists Used in moderate to severe Alzheimer’s, these drugs regulate the activity of glutamate, an important neurotransmitter, to prevent excessive neuronal excitation that can lead to cell damage.
• Novel Medications A range of innovative drugs are currently in clinical trials, with most aimed at slowing disease progression. These treatments are intended to help people in the early stages retain cognitive abilities longer before symptoms like memory loss occur.

Non-Medication-Based Treatment

• Cognitive Therapy Puzzles, memory exercises, and other activities that stimulate memory and cognitive abilities can help slow mental decline.
• Physical Therapy and Exercise Regular physical activity improves overall health, helps maintain motor skills, and elevates mood, counteracting the increased risk of depression associated with Alzheimer’s.
• Nutrition A diet rich in antioxidants, vitamins, and omega-3 fatty acids can improve cognitive abilities. Studies indicate that these nutrients have neuroprotective properties that may reduce the risk of neurodegenerative diseases. A 2019 study published in the Journal of Alzheimer's Disease found that an antioxidant-rich diet significantly improved cognitive functions in older adults and slowed disease progression.
• Psychosocial Support Counseling, group therapy, and social activities enhance mental health and well-being for both patients and their families.
• Environmental Adjustments Clear signage, well-lit spaces, and safe furniture arrangements help patients maintain orientation, even as the disease progresses.

Prevention

Like most forms of dementia, Alzheimer’s can be prevented through a healthy lifestyle, which includes:

• Mental activity
• Physical activity
• Social engagement
• Avoiding alcohol, smoking, other drugs, and fine dust exposure
• Regular medical check-ups

For more detailed information on these preventive measures, you can find our comprehensive article here.

Ultimately, however, dementia can generally only be slowed, not entirely stopped. This is why early diagnosis and attentive monitoring are so important, enabling those affected to live with dignity for as many years as possible.

To understand why imaging techniques are so helpful here, it’s essential to briefly discuss brain volume loss and its specific consequences.

Brain Volume Loss and Its Significance

Brain volume loss (brain atrophy) occurs when, as happens in neurodegenerative diseases, nerve cells (neurons) and their connections (synapses) die.

The loss of brain volume can lead to a variety of different impairments. The primary ones include:

• Cognitive impairments (e.g., memory loss, reduced learning ability, indecisiveness)
• Motor impairments (e.g., movement disorders, coordination problems)
• Behavioral changes (e.g., depression, anxiety, aggression)
• Communication issues (e.g., difficulties in speaking and writing)

Depending on the location and specific nature of the brain volume loss, several of these impairments or even additional ones may occur.

Specific Types of Brain Volume Loss

Below, we present the most common specific types of brain volume loss.

Cerebral Brain Volume Reduction

Cerebral brain volume reduction refers to the loss of brain tissue in the cerebrum. The cerebrum is the largest part of the brain and includes the two cerebral hemispheres. Thinking, memory, emotions, sensory perceptions, language, and voluntary movements are all controlled by the cerebrum.

A reduction in volume, such as that caused by Alzheimer’s disease or frontotemporal dementia, consequently leads to symptoms like memory loss, language problems, or personality changes.

Cerebellar Brain Volume Reduction

Cerebellar brain volume reduction affects the cerebellum, which is responsible for balance, coordination of movements, and fine motor skills.

The consequences include impaired movement coordination, balance problems, and difficulties with fine motor skills.

Hippocampal Brain Volume Reduction

As the name suggests, this type of brain volume loss refers to the hippocampus. The hippocampus is crucial for spatial memory formation and the transition of memories from short-term to long-term memory. It also plays an important role in learning new information and regulating emotions.

Among neurodegenerative diseases, Alzheimer's disease most commonly causes hippocampal brain volume reduction. However, frontotemporal dementia, Parkinson's disease, and Huntington's chorea can also affect the hippocampus in the later stages.

A loss of hippocampal brain volume typically leads to difficulties in learning new information and retrieving stored knowledge, as well as disorientation and emotional instability.

Frontal Brain Volume Reduction

This type of volume reduction primarily affects the frontal lobes of the brain, which are responsible for functions such as planning and organization, decision-making, speech production, impulse control, and social behavior.

Although other neurodegenerative diseases can also cause frontal brain volume reduction, frontotemporal dementia (FTD) poses the greatest risk in this context.

The consequences of frontal brain volume reduction are extremely varied. Significant impairments in so-called executive functions, such as planning, organization, and impulse control, often lead to inappropriate behavior in affected individuals. Articulation problems, mood swings, and a lack of motivation that can lead to apathy are also typical consequences.

What Does an MRI Show in Neurodegenerative Diseases?

Since neurodegenerative diseases are treatable but not curable, MRIs are used not only to support diagnosis but also for regular monitoring of disease progression. This allows for timely detection of changes in the disease profile and for treatments to be adjusted accordingly.

But what exactly does an MRI "see" in neurodegenerative diseases?

Structural and Vascular Changes

Volume reductions (atrophies)—whether general or localized—are structural changes in the brain. An MRI can capture such deviations from the norm or changes compared to previous images very clearly and precisely. It can also detect microbleeds in the MRI, which may indicate a condition known as vascular dementia.

Functional Changes

In later stages, neurodegenerative diseases can also cause functional changes in the brain, which can be observed in functional magnetic resonance imaging (fMRI). These include impairments in connectivity, meaning the communication between different brain regions.

Microstructural Changes

Advanced MRI techniques, such as diffusion imaging, can reveal microstructural changes in the brain (e.g., axonal damage or myelin loss) that may be associated with neurodegenerative diseases.

If you want to learn more about how an MRI actually works and what it can achieve in prevention and diagnosis, you can find our detailed articles on “MRI 101” and “When and Why MRI” here.

Conclusion

Neurodegenerative diseases like Alzheimer’s dementia are incurable, but their progression can be slowed, and symptoms can be treated. This significantly enhances the quality of life for those affected over decades.

A timely diagnosis and close monitoring of the disease progression, facilitated in part by MRIs, are crucial. In particular, the brain changes typical of neurodegenerative diseases can be clearly identified using MRI scans.

Patients and individuals at risk should utilize such imaging techniques for regular medical monitoring to initiate or adjust treatment swiftly if necessary.

An MRI is a valuable tool for the early detection and diagnosis of neurodegenerative diseases such as Alzheimer’s or frontotemporal dementia. However, it is important to note that MRIs cannot predict a future dementia diagnosis before the first signs or symptoms of a neurodegenerative disease appear. The MRI can reveal structural changes in the brain, such as brain volume loss, once they have already occurred.