Dementia is a term used to describe a group of diseases and illnesses that affect your memory, thinking, and the ability to perform daily activities.
Some people with dementia may have trouble controlling their emotions or behaving appropriately in social situations. It usually gets worse over time, which means that you have to rely on other people more and more.
It’s estimated that about 50 million people have dementia worldwide, over 70% are 75 years old and older. Among them, about 60% to 70% are estimated to have Alzheimer’s disease.
What Causes Dementia?
Dementia is caused by a variety of diseases, which result in damage to brain cells or changes in the brain that cause nerve cells and their connections to stop working properly. When brain cells cannot communicate normally, thinking, behavior and feelings can be affected.
Researchers have connected changes in the brain to certain forms of dementia and are investigating why these changes happen in some people but not others. For a small number of people, rare genetic variants that cause dementia have been identified.
Different types of dementia are associated with particular types of brain cell damage in particular regions of the brain. Here are five common types of dementia:
Alzheimer’s disease is the most common cause of dementia, accounting for 50%-70% of all dementia cases. Although the exact cause of Alzheimer’s disease isn’t known, but it is likely due to plaques and tangles in the brain. Plaques are deposits of beta-amyloid protein that accumulate between nerve cells, and tangles are deposits of tau protein that accumulate in the nerve cells.
Vascular Dementia is another common form of dementia that is caused by reduced blood flow to the brain — usually due to narrowing of the small blood vessels deep inside the brain. When blood flow is reduced, brain cells can’t function properly, causing damage to the cortex of the brain – the area that is associated with memory, language, and learning.
Lewy body dementia (LBD)
Lewy body dementia (LBD) is one of the most common types of progressive dementia – it will develop slowly and get gradually worse over time. This happens when clumps of proteins called Lewy bodies build up in your brain, causing the brain cells not to work well and eventually die.
Frontotemporal dementia (FTD)
Frontotemporal dementia (FTD) is a rare form of dementia that tends to occur in people younger than 60. It is caused by progressive nerve cell loss in the frontal lobes (the areas behind your forehead) or temporal lobes (the areas behind your ears) of the brain.
Depending on where it starts in your brain, this condition affects your behavior, personality, language, and movement.
Mixed dementia is a combination of two or more types of dementia. The most common combination is Alzheimer’s disease with vascular dementia.
A person living with mixed dementia may show symptoms of both Alzheimer’s and vascular dementia. Because many symptoms overlap between different types of dementia, it can be hard to figure out if someone has mixed dementia.
Risk Factors for Dementia
Researchers have identified several risk factors that affect the likelihood of developing one or more forms of dementia. Some of these factors can be changed and some can not.
Dementia risk factors that cannot be changed:
Age is the greatest risk factor for developing dementia. This means as you get older, your risk of developing dementia increases.
Genetics/ family history
There are two types of genes that are linked to dementia: risk genes and deterministic genes.
- Risk genes increase a person’s chances of developing dementia. Scientists have found a number of genes that increase the risk of Alzheimer’s disease. APOE-e4 is the first risk gene identified and remains the gene with strongest impact on risk. It is estimates that between 40-65% of people diagnosed with Alzheimer’s have the APOE-e4 gene.
People who inherit one copy of APOE-e4 from their father or mother are around three times more likely to develop late onset Alzheimer’s disease. Those who inherit two APOE e4 genes, one from each parent, have an even higher risk, about eight- to twelvefold.
- Deterministic genes will definitely cause dementia if they are passed down from a parent to a child. These genes are very rare and only account for less than 1% of all Alzheimer’s disease cases. If a deterministic gene is inherited, the disease is usually early-onset, meaning that the person will develop the condition in their 40s or 50s.
Dementia risk factors that can be changed through lifestyle choices:
- High blood pressure (hypertension)
- High blood cholesterol
- Excessive alcohol intake
- Head injury
- High homocysteine levels in the blood
What are the Symptoms of Dementia?
Symptoms of dementia vary depending on the types of brain changes involved and the areas of the brain affected. They begin mildly and get worse over time. Eventually, most people with dementia will need others to help with daily activities.
Short term memory loss is the early sign of dementia. People with early dementia may not remember what they were just said or done. However, just memory loss alone does not mean that a person has dementia. Some other symptoms to watch for include:
How is Dementia Diagnosed?
To diagnose dementia, your healthcare provider will ask about the course of your symptoms, your medical history, as well as your family history of disease including dementia.
They may also order laboratory tests, imaging tests, neurocognitive tests (thinking tests), and/or psychiatric evaluation to help determine a diagnosis.
Doctors may use a variety of laboratory tests to rule out other conditions that may cause dementia, such as infection, underactive thyroid and vitamin deficiency, especially vitamin B12.
Sometimes, they may order cerebrospinal fluid tests to evaluate autoimmune conditions and neurodegenerative diseases, if warranted.
Your healthcare provider may order the following imaging tests of your brain:
A magnetic resonance imaging (MRI) scan is a standard structural imaging test for potential Alzheimer’s patients. An MRI uses magnetic fields and radio waves to create detailed images of your brain. These imaging tests look for evidence of stroke, bleeding, tumors and fluid on your brain.
In some cases, a dementia MRI can show whether the patient has high levels of beta-amyloid, which is a notable sign of Alzheimer’s.
Similar to an MRI, a computed tomography (CT) scan can produce detailed images to help doctors evaluate whether a patient’s symptoms stem from dementia or another conditions.
CT scans, which use X-rays to detect brain structures, can show evidence of brain atrophy, strokes and ischemia, changes to the blood vessels, and other problems such as hydrocephalus and subdural hematomas.
Positron emission tomography (PET) scan is another helpful imaging test for diagnosing dementia. It uses a radioactive substance called a tracer to look for disease or injury in the brain.
PET scan can detect changes in glucose metabolism, presence of amyloid proteins, oxygen metabolism, and blood flow, all of which can reveal abnormalities of the brain function.
Usually, a PET scan is only ordered if the patient’s initial MRI or CT scan results were inconclusive or uncertain.
Cognitive and neurological tests
During cognitive and neurological tests, your healthcare provider will evaluate your thinking and mental abilities. These tests include assessments of memory, reasoning, planning, problem solving, language skills, as well as balance, sensory response, and reflexes.
If someone is experiencing behavioral or mood changes, a psychiatric evaluation may be recommended to help determine whether depression or another mental health condition is contributing to a person’s symptoms.
How is Dementia Treated?
Currently, there is no cure for dementia. The goal of dementia treatment is to control the symptoms of dementia and improve their quality of life.
People with dementia can take steps to maintain their quality of life and promote their well-being by being physically active and taking part in activities and social interactions that stimulate the brain and maintain daily function.
In addition, some medications can help manage dementia symptoms. They include:
- Cholinesterase inhibitors, like donepezil and galantamine, to treat Alzheimer disease.
- Memantine to slow the progression of moderate-to-severe Alzheimer’s disease.
- Medicines to treat accompanying symptoms such as depression and anxiety in people living with dementia if lifestyle and social changes don’t work, but these should not be the first option.
If people living with dementia are at risk of hurting themselves or others, medicines like haloperidol and risperidone can help, but these should never be used as the first treatment.