Pathophysiology Of Dementia In The Brain: What Causes It?

Dementia is a significant public health concern that impacts an estimated 55 million people globally. Associated with various cognitive, behavioral, and motor function complications, dementia is a group of symptoms that occur in various conditions—not a disease unto itself. There are several ways dementia can materialize, with each illness affecting the body physiologically in varying ways. This process is generally known as pathophysiology, and its goal is normally to explain the changes that happen in the body when a disease is present. Some of the most common ailments leading to dementia can include Alzheimer’s disease, Parkinson’s disease, strokes, Creutzfeldt-Jakob disease, chronic traumatic encephalopathy, and Wernicke-Korsakoff syndrome. Although dementia cannot currently be cured, symptoms can be treated. A diagnosis of dementia in yourself or a loved one can be challenging to cope with, but in-person or online therapy may help.

Risk factors of dementia

Multiple diseases and events can bring about the onset of dementia. However, the degradation of nerve cells in the brain, whether through biological or external means, is usually the specific reason why dementia develops.

Some diseases that cause dementia may develop due to infections, like Creutzfeldt-Jakob disease (a sporadic prion disease). Infections that cause Creutzfeldt-Jakob disease can occur following surgical procedures or the consumption of contaminated beef. Other diseases are caused by the narrowing and damaging of blood vessels in the brain, perhaps from a stroke. Vascular dementia is one such condition. Genetic factors can also play a critical part in the formation of dementia, such as with Huntington's disease and Alzheimer's disease.

External factors, such as repeated head injuries and concussions, can be responsible for chronic traumatic encephalopathy (CTE) and dementia pugilistica. Sports that involve extreme physical contact can also be associated with these injuries. Additionally, poor cardiovascular health is associated with an increased risk of dementia. Alcohol use can be another non-biological source of brain degradation that can increase an individual’s risk of developing dementia, especially early-onset dementia. 

Mixed dementia: Comorbid frontotemporal dementia and Alzheimer’s disease

Even though they frequently have different roots, all these diseases tend to have one thing in common: They usually damage the brain, which can lead to dementia. This similar pathophysiology can help explain why different types of dementia often co-occur, a phenomenon called mixed dementia. An example of mixed dementia is comorbid frontotemporal dementia and Alzheimer’s disease, both of which impact the cerebral cortex. The two conditions, however, affect different cortical regions, which can lead to varied cognitive, behavioral, and emotional challenges. And even though these different forms of dementia cause degeneration, the mechanisms by which they destroy brain cells can vary.

Pathophysiology of dementia-causing diseases

Understanding the pathophysiology of dementia can be essential, as it may lead to better treatment options. Discoveries of links between various physiological phenomena and symptoms of dementia can have significant clinical implications, helping inform the development of medications, therapeutic modalities, and other interventions. While there is currently no cure for dementia itself or many of the diseases that are connected to it, research can still be vital because it may help experts delay the progression of the symptoms or eventually provide a cure. The following includes some of the most prevalent sources of dementia and what we know about them.

Alzheimer's disease

Perhaps the most well-known cause of dementia, Alzheimer’s disease is often associated with older people, causing memory loss and other forms of cognitive decline. It generally affects at least 12 million people around the globe, usually 60 years old or older, and that number is projected to increase by 700,000 by 2050.

The etiology of Alzheimer’s disease

The cause of Alzheimer's is not entirely understood yet, but research over the years has provided us with some clues to its origins. It's usually believed that genetic and environmental factors can play a role, along with lifestyle choices. Plaques in the brain, caused by the accumulation of the protein amyloid beta, along with neurofibrillary tangles, are often associated with Alzheimer's cases. The amyloid structures can lead to adverse effects in the brain and cause cell death. Researchers are currently developing blood tests that can identify clusters of amyloid beta and potentially help with early diagnosis of Alzheimer’s. 

Alzheimer’s in midlife vs. in older adults

There are thought to be physiological differences in those who develop dementia from Alzheimer’s in midlife and those who develop it as older adults. In a systematic review, researchers found that early-onset Alzheimer’s disease is associated with greater degeneration in the cortex than late-onset Alzheimer’s. 

A neurodegenerative disease that results in memory loss and cognitive impairment

This chronic neurodegenerative disease destroys neuron connections in the brain, which results in a decline in memory, cognitive functioning, and language skills. Alzheimer’s disease is irreversible, and eventually, many neurons will stop functioning normally.

Parkinson's disease

Parkinson's is normally the second most common condition resulting in dementia, usually in its more advanced stages. Parkinson’s disease dementia can cause memory loss, executive dysfunction, and other forms of cognitive impairment. However, Parkinson's disease is mostly known for its motor symptoms, which may include:

• Rigidness

• Shaking

• Movement difficulties

In Parkinson’s disease, cell death can be connected to the build-up of proteins in the brain, known as Lewy bodies. These tend to gather in the basal ganglia, the substantia nigra, as well as the thalamus and the cortex, which usually causes a reduction in dopamine. Dopamine is a neurotransmitter that frequently plays several critical roles in the body, such as motor control. 

Strokes/vascular dementia

Strokes can be a major cause of disability due to their profound impact on the brain. A stroke can be defined as an event where inadequate blood flow is provided to the brain, potentially causing cell death. This lack of blood supply can be thought of as the pathophysiology of vascular dementia. 

Dementia in stroke patients is usually created by the reduced blood supply from blocked vessels, which frequently leads to progressive cognitive impairment. Minor strokes are also risk factors for vascular dementia. Diabetes, high blood pressure, smoking, and certain types of vascular disease can also reduce blood supply to certain brain regions, increasing an individual’s vascular dementia risk. 

Chronic traumatic encephalopathy

Chronic traumatic encephalopathy (CTE) is a term that usually refers to repeated head injuries leading to brain degeneration. It's typically most common in athletes who can be prone to concussions during sports, such as boxing and American football. CTE has also been discovered in military veterans.

The dementia associated with CTE is normally known as dementia pugilistica. Pugilistica may be derived from the word pugilist, which can refer to a prizefighter, like a boxer. The pathophysiology of CTE usually involves Tau proteins that clump in the brain.

Chronic traumatic encephalopathy may appear very early in one's life, or it can appear many years later. This is generally different from other conditions in which dementia usually does not start showing signs until much later in life. Also, unlike other diseases, CTE may not be formally diagnosed until a patient is deceased.

Wernicke-Korsakoff syndrome/alcohol-related dementia

This condition can be seen as the merger of two separate diseases: Wernicke's encephalopathy and Korsakoff syndrome. Wernicke's can involve movement pattern and coordination issues, while Korsakoff's symptoms typically include memory loss, personality changes, and hallucinations.

Wernicke-Korsakoff syndrome (WKS) is usually caused by a thiamine (vitamin B-1) deficiency. This issue can arise from malnutrition and alcoholism. The pathophysiology of this condition normally involves sugar and energy. If there's not enough thiamine, the brain cells may not have adequate fuel to perform tasks.

Unlike some of the other diseases mentioned above, WKS can be treatable through thiamine supplementation, and people can make a full recovery if caught early enough. Alcohol abstinence is often required to prevent dementia symptoms from progressing, as alcohol can impact the body's ability to absorb and use thiamine, especially in the brain. Chronic alcohol use can shrink brain cells. Additionally, it can be highly toxic for other body parts and organs, such as the liver and the heart.

Lewy body dementia: A common neurodegenerative disease

Lewy body dementia is a common neurodegenerative disease that impacts an estimated one million adults in the US. Also called Lewy body disease, Lewy body dementia affects cognitive function, movement, mood, and behavior. It can also cause visual hallucinations. These symptoms typically worsen as the disease progresses. Lewy body dementia is caused by deposits of a protein called alpha-synuclein in the brain. Clusters of alpha-synuclein, called Lewy bodies, can also cause Parkinson disease dementia. 

Alpha-synuclein influences the function of certain neurotransmitters in patients with dementia with Lewy bodies. For example, reduced dopamine transporter uptake in the basal ganglia—which is part of the diagnostic criteria for Lewy body dementia—can be impacted by interactions with alpha-synuclein. Alterations in levels of dopamine transporters are thought to contribute to the cognitive challenges of dementia. 

What treatment options are there for the pathophysiology of dementia in the brain?

Except for Wernicke-Korsakoff syndrome (in which most symptoms can be reversed, but not cured), dementia and its associated diseases are usually incurable and cannot be reversed.

It is possible to treat the symptoms of Alzheimer’s disease and other forms of dementia

Treatment may not address the pathophysiology of dementia in the brain. However, it can be possible to treat dementia symptoms, such as impaired cognitive function, through prescribed medications and other interventions. According to the Alzheimer’s Association, medications like cholinesterase inhibitors can alleviate the cognitive and behavioral effects of dementia. Early diagnosis can help improve the likelihood of positive outcomes from medication.

Medication requires proper diagnosis

Please keep in mind that a proper diagnosis from a doctor is normally required to receive medication. This prerequisite can exclude chronic traumatic encephalopathy, which relies on symptoms because it currently cannot be diagnosed until one's death. However, regardless of the diagnosis, medication options are typically the same. A physician will also be able to provide information regarding dosages and side effects.

Safer home for people with the pathophysiology of dementia

While not a direct treatment, making a home dementia-friendly can be essential. Doing this usually involves making the living space safe and organized. Furniture, loose rugs, and other obstructions should generally be moved to prevent accidents. Frequently used items should be labeled and easy to reach.

Therapeutic activities that keep the brain active

Some therapeutic activities that do not involve medication can include exercise, games, and puzzles. These can improve the patient's mood and keep the brain active. Social interaction during physical exercise programs and other activities is often encouraged as well. Participating in a book club, taking cooking classes, or playing board games can be sources of mental and social stimulation for individuals with dementia. 

Getting help as a caregiver

Seeing a loved one struggling and watching their memories slowly disappear can be incredibly challenging, especially if you are a primary caregiver. You may also feel confused and lost about what steps to take and what to expect. Consider enlisting the services of a licensed therapist. They can answer any questions you might have about how to assist a loved one with dementia, and they can also provide the support you deserve for your own mental health. 

Benefits of online therapy for caregivers of a person with dementia

Online therapy can be a simple and available way to receive support as the caregiver of a person living with dementia. You may find it difficult to leave home and set up sufficient care for your loved one while you attend therapy, so the opportunity to attend sessions from the comfort of your home can be convenient. In addition, online therapy can make it easy to match with a therapist who has experience helping others come to terms with a dementia diagnosis.

Effectiveness of online therapy for caregivers of people with signs and symptoms of dementia

A 2022 study investigated the efficacy of online cognitive behavioral therapy for family caregivers of people with dementia. It found that this online intervention generally decreased distress in the caregivers and empowered them to manage upsetting thoughts related to the dementia diagnosis.