Research Into The Genetics Of Dementia
Genes carry patterns for the many proteins that form our bodies. Proteins are the essential building blocks of life – forming cells, organs, and enzymes which help the body to function. Once they are made, proteins can be folded into different structures and shapes to fulfil their many functions. Genes are found in every cell in the body in packages of twisted DNA called chromosomes. Half of these chromosomes are inherited from each parent – providing the basis for genetic inheritance. Genes explain why family resemblances occur and why some diseases can run in families.
There is still much we don’t know about the role of genes in Alzheimer’s disease and other dementias, but researchers continue to study this area. In most cases, dementia occurs sporadically, is not directly caused by a single gene and has no clear pattern of family inheritance. However, in a minority of cases, Alzheimer’s disease and some other types of dementia can be directly caused by an inherited gene mutation. The table below summarises some of the genes that have been found to cause or be involved in dementia. Each type is discussed in more detail under the relevant section below.
Risk Factors And Prevention
Although age is the strongest known risk factor for dementia, it is not an inevitable consequence of ageing. Further, dementia does not exclusively affect older people young onset dementia accounts for up to 9% of cases. Studies show that people can reduce their risk of dementia by getting regular exercise, not smoking, avoiding harmful use of alcohol, controlling their weight, eating a healthy diet, and maintaining healthy blood pressure, cholesterol and blood sugar levels. Additional risk factors include depression, low educational attainment, social isolation, and cognitive inactivity.
Dementia Caused By A Complex Disease
Nearly all cases of dementia are the result of a complex disease. In these cases, genes may increase the risk of developing dementia, but they dont cause it directly.
What causes complex disease dementias?
When dementia is the result of a complex disease, it is likely to be caused by a combination of risk factors. These include:
- non-genetic factors for example, members of the same family may all smoke or have an unhealthy diet, which are both risk factors for dementia.
- genetic factors a person may inherit the same dementia risk variants as other members of their family. This could include variants in genes such as APOE.
These factors are often shared by members of the same family. This is why many people have some family history of dementia for example, they may have a parent who developed dementia in their 90s and a brother who developed dementia in his 70s. This is not the same as familial dementia.
Is it possible to directly inherit dementia when it’s caused by a complex disease?
No. People who are related to each other by birth are more likely to have the same risk variants as each other. However, risk variants for dementia do not directly cause dementia . This means that its not possible to directly inherit dementia through risk variants.
However, a person who has dementia risk variants is at higher risk of developing dementia than someone who does not have risk variants. Despite this higher risk, they still might not develop dementia.
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Dementia With Lewy Bodies
Dementia with Lewy bodies, also known as Lewy body dementia, is caused by protein deposits in nerve cells. This interrupts chemical messages in the brain and causes memory loss and disorientation.
People with this type of dementia also experience visual hallucinations and have trouble falling asleep at night or fall asleep unexpectedly during the day. They also might faint or become lost or disoriented.
Dementia with Lewy bodies shares many symptoms with Parkinson and Alzheimer diseases. For example, many people develop trembling in their hands, have trouble walking, and feel weak.
Diagnosing Mild Cognitive Impairment
The benefit to a proper MCI diagnosis is that your older adult will know that their cognitive issues arent caused by a medication side effect or other treatable conditions that cause dementia-like symptoms and could be mistaken for MCI.
Plus, theyll know if they have an increased risk of developing dementia.
That means doctors can monitor them regularly so if they do develop dementia, they can be diagnosed and treated as early as possible for maximum effectiveness.
The steps to diagnose MCI is very similar to those used to diagnose dementia.
- Thorough medical history, including current symptoms, previous illnesses and medical conditions, and any family history of significant memory problems or dementia
- Assessment of independent function and daily activities, focusing on any changes from the usual level of function
- Input from family or a trusted friend to get additional perspective on how cognitive function might have changed
- Assessment of mental status using brief tests that evaluate memory, planning, judgment, ability to understand visual information, and other key thinking skills
- In-office neurological exam to assess the function of nerves and reflexes, movement, coordination, balance, and senses
- Check for depression, which is common among older adults and can cause some dementia-like symptoms including problems with memory or feeling foggy
- Lab tests including blood tests and brain imaging
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Research Into Other Causes Of Dementia
Dementia is also associated with other conditions such as AIDS, Creutzfeld-Jakob disease, chronic alcohol abuse, Down Syndrome, Huntingtons disease and Parkinsons disease.
- A genetic component has been found for a very rare subtype of Creutzfeld-Jakob disease.
- Individuals with Down Syndrome have an extra copy of chromosome 21, which contains the gene for the Amyloid Precursor Protein, increasing their likelihood of developing Alzheimers disease.
- Huntingtons disease is caused by a mutation in the gene that codes for the huntingtin protein. Everyone who inherits the mutated version of this gene will eventually develop the disease. Dementia occurs in the majority of cases.
There Are Many Causes Of Dementia
Any of these symptoms can be caused in multiple ways. Alan, for example, was found to suffer from cognitive impairment related to his HIV infection Martha had Alzheimers disease interfering with her short-term memory and comprehension. Bert, after his diagnostic work up, was recognized to have frontotemporal dementia leading to difficulty controlling behavior and aphasia . Mary had vascular cognitive impairment following her stroke. Bill had suffered brain damage due to oxygen deprivation during his drowning. Each was considered to have dementia, yet the differences between them were huge. In each case, however, an injury or disease process was responsible for destruction of brain cells.
Causes of dementia may include:
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Dementia Can Be Hard To Diagnose Early On
Dr. William Nields, medical director of Cognitive Health Centers in Sarasota, Florida told US News, “The symptoms are very subtle in the beginning and almost unnoticeable. For that reason, most people are not diagnosed with Alzheimer’s or one of the other many brain diseases that causes dementia until they’ve already progressed into their mid-stage.” He also stated, “In the case of Alzheimer’s Disease, beta amyloid plaques may be building up in the brain 20 years before dementia, and years before symptoms are even present,” Nields says. Dementia is typically diagnosed after “significant cognitive decline has occurred and a person has difficulty caring for themselves.”
Symptoms Of Mild Cognitive Impairment
Someone with mild cognitive impairment could experience these symptoms:
- Forgetting recent events or repeating the same question
- Forgetting important events like appointments or social events
- Being very easily distracted, losing their train of thought, or losing the thread of conversations, books, or movies
- Feeling increasingly overwhelmed by decision-making, planning, or understanding instructions
- Taking much longer than usual to find the right word for something
- Starting to have trouble finding their way around familiar places
- Becoming more impulsive or showing increasingly poor judgment
- Difficulty judging distances or navigating stairs
- Family and friends noticing any of these changes
They may also have:
These changes may cause someone with MCI to need a little help with the more difficult everyday tasks .
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Less Common Forms Of Dementia
Picks Disease affects personality, orientation and behavior. It may be more common in women and occurs at an early age.
Creutzfeldt-Jakob Disease progresses rapidly along with mental deterioration and involuntary movements.
Huntingtons Disease is an inherited, degenerative disease. The disease causes involuntary movement and usually begins during mid-life.
Parkinsons Disease Dementia can develop in the later stages of Parkinsons disease, a progressive disorder of the central nervous system.
Lewy Body Dementia causes symptoms similar to Alzheimers disease. People with Lewy Body dementia experience hallucinations and can become fearful.
Mild cognitive impairment
Mild cognitive impairment is a stage between normal aging and dementia and involves problems with memory, language, or other cognitive functions. But unlike those with full-blown dementia, people with MCI are still able to function in their daily lives without relying on others.
Many people with MCI eventually develop Alzheimers disease or another type of dementia. However, others plateau at a relatively mild stage of decline and are able to live independently. Some people with mild cognitive impairment even return to normal.
Symptoms of MCI include:
- Frequently losing or misplacing things.
- Frequently forgetting conversations, appointments, or events.
- Difficulty remembering the names of new acquaintances.
- Difficulty following the flow of a conversation.
What Are The Most Common Types Of Dementia
- Alzheimers disease. This is the most common cause of dementia, accounting for 60 to 80 percent of cases. It is caused by specific changes in the brain. The trademark symptom is trouble remembering recent events, such as a conversation that occurred minutes or hours ago, while difficulty remembering more distant memories occurs later in the disease. Other concerns like difficulty with walking or talking or personality changes also come later. Family history is the most important risk factor. Having a first-degree relative with Alzheimers disease increases the risk of developing it by 10 to 30 percent.
- Vascular dementia. About 10 percent of dementia cases are linked to strokes or other issues with blood flow to the brain. Diabetes, high blood pressure and high cholesterol are also risk factors. Symptoms vary depending on the area and size of the brain impacted. The disease progresses in a step-wise fashion, meaning symptoms will suddenly get worse as the individual gets more strokes or mini-strokes.
- Lewy body dementia. In addition to more typical symptoms like memory loss, people with this form of dementia may have movement or balance problems like stiffness or trembling. Many people also experience changes in alertness including daytime sleepiness, confusion or staring spells. They may also have trouble sleeping at night or may experience visual hallucinations .
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What Are The Symptoms Of Dementia
Early symptoms of dementia include :
- Forgetting recent events or information
- Repeating comments or questions over a very short period of time
- Misplacing commonly used items or placing them in usual spots
- Not knowing the date or time
- Having difficulty coming up with the right words
- Experiencing a change in mood, behavior or interests
Signs that dementia is getting worse include:
- Ability to remember and make decisions further declines
- Talking and finding the right words becomes more difficult
- Daily complex tasks, such as brushing teeth, making a cup of coffee, working a tv remote, cooking, and paying bills become more challenging
- Rational thinking and behavior and ability to problem solve lessen
- Sleeping pattern change
- Anxiety, frustration, confusion, agitation, suspiciousness, sadness and/or depression increase
- More help with activities of daily living grooming, toileting, bathing, eating is needed
- Hallucinations may develop
The symptoms mentioned above are general symptoms of dementia. Each person diagnosed with dementia has different symptoms, depending on what area of the brain is damaged. Additional symptoms and/or unique symptoms occur with specific types of dementia.
What Is The Life Expectancy For A Person With Dementia
The outlook for most types of dementia is poor unless the cause is an early recognized reversible condition. Irreversible or untreated dementia usually continues to worsen over time. The condition usually progresses over years until the person’s death. Life expectancy after diagnosis averages about 8-10 years with a range from about 3-20 years.
Making decisions about end-of-life care is important.
- The earlier in the disease these issues are discussed, the more likely the person with dementia will be able to express his or her wishes about medical care at the end of life.
- The issues may be presented by your health care professional. If not, ask about them.
- These issues include use of aggressive interventions and hospital care, artificial feeding, and medical treatment for medical illnesses.
- These issues should be discussed by family members and decisions made about how to deal with them when the time comes.
- The decisions should be documented in the person’s medical records.
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What Medications Treat Dementia Symptoms
Dementia treatment focuses on correcting all reversible factors and slowing irreversible factors. Some of the important drug treatment strategies in dementia are described. Except for the cholinesterase inhibitors, the U.S. Food and Drug Administration has not approved any drug specifically for dementia. The drugs listed here are some of the most frequently prescribed from each class.
Slowing the progression of dementia
Dementia due to some conditions, such as Alzheimer’s disease, can sometimes be slowed in the early-to-intermediate stages with medication. Many different types of medications have been or are being tried in dementia. The medications that have worked the best so far are the cholinesterase inhibitors.
Because depression is so common in people with dementia, treatment of depression can at least partially relieve symptoms.
- Depression is usually treated with any of a group of drugs known as antidepressants.
- The most important of these are the drugs known as selective serotonin reuptake inhibitors , for example, Fluoxetine , sertraline , paroxetine , citalopram .
- Stimulant drugs such as methylphenidate may sometimes be used to treat depression in people with dementia.
- Some of the medications that treat depression also help with anxiety.
Correcting drug doses and/or withdrawing misused drugs
How Dementia Causes Death
A person in the late stage of dementia is at risk for many medical complications, like a urinary tract infection and pneumonia . They’re at an even higher risk of certain conditions because they’re unable to move.
Trouble swallowing, eating, and drinking leads to weight loss, dehydration, and malnutrition. This further increases their risk of infection.
In the end, most people with late-stage dementia die of a medical complication related to their underlying dementia.
For example, a person may die from an infection like aspiration pneumonia. This type of pneumonia usually happens because of swallowing problems.
A person may also die from a blood clot in the lung because they are bedbound and not mobile.
It’s important to know that late-stage dementia is a terminal illness. This means that dementia itself can lead to death. Sometimes this is appropriately listed as the cause of death on a death certificate.
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Difficulty Forming The Words To Speak
When people who used to be fluent and could speak smoothly stop being able to produce language that way, this may be a sign of dementia, says Rankin. Despite this symptom, patients are often crystal clear in other areas. They can run a business, manage their family, or draw beautifully, but they have increased difficulty actually forming the words to speak.
Research Into The Cause Of Dementia With Lewy Bodies
Dementia with Lewy bodies is characterised by the presence of abnormal spherical structures, called Lewy bodies, which develop inside nerve cells in the brain. Lewy bodies are accumulations of a protein called alpha-synuclein. It is thought that these contribute to the degeneration and death of nerve cells.
Dementia with Lewy bodies sometimes co-occurs with Alzheimers disease and/or vascular dementia. It may also be hard to distinguish dementia with Lewy bodies from Parkinsons disease, which is also associated with Lewy bodies, and some people who have Parkinsons disease develop a similar dementia.
At present there is no known cause of dementia with Lewy bodies and no risk factors have been identified. In very rare cases, the disease appears to be inherited, but a genetic cause has not yet been found. In short, we do not know why Lewy bodies form in the brain and research continues in the attempt to find an answer. Much of this research is focussed on searching for the genetic roots of dementia with Lewy bodies, exploring the mechanisms of alpha-synuclein accumulation, and discovering how Lewy bodies cause the particular symptoms of dementia with Lewy bodies.
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Common Forms Of Dementia
There are many different forms of dementia. Alzheimer’s disease is the most common form and may contribute to 6070% of cases. Other major forms include vascular dementia, dementia with Lewy bodies , and a group of diseases that contribute to frontotemporal dementia . The boundaries between different forms of dementia are indistinct and mixed forms often co-exist.
What Is The Difference Between Delirium And Dementia
Both delirium and dementia have similar symptoms, but the two medical conditions are not the same. Delirium usually comes on suddenly, and there are ways to prevent it from developing. The onset of dementia is slower, usually taking months or years to develop with minor symptoms sometimes being dismissed as normal forgetfulness or ignored. With this information, you should be able to tell the differences between delirium vs dementia and understand why awareness of delirium and its causes is important.
Some memory lapses are a natural part of aging, but when it is combined with confusion, disorientation, difficulty concentrating, or speech problems, then there is a reason for concern. Since these symptoms can indicate more than one medical condition, an appointment with a doctor should be made to diagnose the condition.
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