Overview of Dementia
Dementia is best described as an umbrella term used to refer to certain types of severe changes in the brain that leads to memory loss. These changes in the brain make it challenging for people to carry out their basic day-to-day functions and abilities. In many people, dementia can also cause changes in their personality and behavior. As mentioned above, there are different types of dementia, all of which tend to affect three main parts of the brain including:(1, 2, 3, 4)
- Decision-making ability
Most causes are dementia are usually irreversibly and caused by an underlying disease. However, there are some rare exceptions to this, usually observed in cases where the condition is caused by alcohol or drug abuse, or depression. Different types of dementia have different patterns of disease progression, though most types are graded according to a set of similar stages itself.(5, 6)
10 Types of Dementia
Here are the 10 most common types of dementia.
The most common type of dementia is Alzheimer’s disease. According to data from the Alzheimer’s Association, this condition accounts for nearly 60 to 80 percent of all dementia cases.(7) Some of the earliest signs of Alzheimer’s disease include forgetting about recent events and names of people, personality and mood changes, neglecting personal hygiene and overall care, a general disorientation, etc. Sometimes depression can also be an early sign of Alzheimer’s disease, but it is not a symptom of the disease itself and needs to be treated as a separate mental disorder. In some cases, older adults suffering from clinical depression are often misdiagnosed as having Alzheimer’s disease.(8)
The primary feature of Alzheimer’s disease is the death of brain cells. And as the condition progresses further, people start to experience mood changes and confusion or disorientation. Many people also experience difficulty in walking and speaking.(9)
Older adults are at a higher risk of developing Alzheimer’s, but around five percent of cases of this disease are diagnosed in people who are just in their 40s and 50s, a condition referred to as early onset Alzheimer’s.(10, 11)
The progression of Alzheimer’s disease is typically divided into seven stages, with symptoms beginning to appear when a person reaches Stage 2. However, the symptom of clearly defined dementia tends to start at around Stage 4 only. The cognitive impairment in the patient starts to worsen up to Stage 7, after which most people with the condition are prone to experience severe challenges in their movement and speech. As is the case with most types of dementia, the exact level of care required by the patient differs significantly as the symptoms progress through the stages.(12, 13)
There are many known risk factors that are known to come together to increase the likelihood of a person developing Alzheimer’s disease, and none of these causes are very clearly understood. Some of the known risk factors for Alzheimer’s include genetics, age, and family history.(14)
Dementia with Lewy Bodies
Another type of dementia with Lewy bodies is known as Lewy body dementia. Lewy body dementia is caused by deposits of protein in the nerve cells, which interrupts the chemical messages in the brain. This causes disorientation and memory loss.(15, 16, 17)
People with Lewy body dementia also experience symptoms like visual hallucinations and often have trouble falling asleep at night, or they may even go to sleep unexpectedly in the daytime. They may also become disoriented, lost, or may faint.
This type of dementia shares many of its symptoms with Alzheimer’s and Parkinson’s diseases. For example, some people experience trembling in their hands, feel fatigued or weak, and may even have trouble walking. The Lewy bodies that are present in this type of dementia are also known to be present in the brains of patients with Alzheimer’s and sometimes in those with Parkinson’s disease as well. For people with Parkinson’s disease, some of the known risk factors that may lead to the development of Lewy body dementia also include:(18, 19)
- Changes in posture
- Being of the male gender
- Instability while walking
- Experiencing hallucinations in the early stages
- Greater difficulty with movement
- Symptoms that do not respond to medication
- Symptoms that are observed on both the left and right sides of the body
Another type of dementia is known as vascular dementia. Vascular dementia is caused by a lack of blood in the brain. Vascular dementia can develop as you age, and it can be associated with other underlying conditions like diabetes, high blood pressure, atherosclerotic disease, and others. The most common cause of vascular dementia is having a stroke.(20, 21)
The symptom of vascular dementia usually starts to appear slowly, but in some cases, the onset can be sudden, depending on the underlying cause. Disorientation and confusion are usually some of the early signs of this form of dementia. In the later stages, people start having trouble concentrating for long periods of time or completing their tasks. Vascular dementia can also lead to problems with vision, and sometimes patients may also experience hallucinations.
Since vascular dementia is usually caused by discrete events, it usually appears and worsens in a stage-wise manner rather than the progressive decline that happens in Alzheimer’s disease.(22)
There are many risk factors for vascular dementia, including:
Research has shown that most people with Parkinson’s disease go on to develop dementia. Some of the early symptoms of Parkinson’s-related dementia include trouble with judgment and reasoning. For example, a person having Parkinson’s disease dementia is likely to have trouble remembering how to do simple everyday tasks or understanding visual information. Such patients may even experience frightening or confusing hallucinations.(23, 24)
Parkinson-related dementia can also make a person to become irritable. Many people also tend to get paranoid or depressed as the disease starts to progress. On the other hand, some may forget words, have trouble having a conversation, or may get lost while having a conversation.
One of the main risk factors for dementia in people with Parkinson’s disease is a type of motor difficulty that is known as postural instability and gait disturbance (PIGD). PIGD is a condition in which people experience difficulty in movement, including trouble with balancing, falling, or having to shuffle while walking.
Creutzfeldt-Jakob disease (CJD) is one of the rarest types of dementia. According to estimates by the Alzheimer’s Association, only about one in one million people are diagnosed with this condition every year.(27) This condition tends to progress very rapidly, and it is a fatal disease, with people dying within just one year of being diagnosed with CJD.(28)
CJD is caused when abnormal and misfolded proteins, known as prions, begin appearing in the body, which triggers the development of additional prions in the brain, which eventually causes the death of brain cells.
The symptoms of CJD are similar to the other types of dementia, with some people experiencing symptoms like agitation and others having depression. Loss of memory, confusion, muscle stiffness, and twitching of muscles are some of the other common symptoms of this disease.(29, 30, 31)
Frontotemporal dementia is an umbrella term used to refer to a variety of dementia. All the types of dementia that fall under frontotemporal dementia have one thing in common, that is they only affect the frontal and side areas of the brain. These parts of the brain are the parts that control behavior and language. This form of dementia is also known as Pick’s disease. However, it is important to note that these types of dementia show up in multiple forms.
While dementia is usually associated with older people, frontotemporal dementia, though, is known to impact people as young as 45 years old. However, researchers have no idea what exactly causes this condition, except that it tends to run in families. People who have mutations in some genes are more prone to have this form of dementia.(32)
Frontotemporal dementia causes a loss of motivation and inhibitions in a patient and also leads to compulsive behavior. Like other forms of dementia, patients with this form of dementia also experience problems with their speech, including forgetting what some common words mean. In some cases, frontotemporal dementia has some severe effects on speech, even more so than Alzheimer’s disease. However, unlike what happens in Alzheimer’s, problems with memory that stem from frontotemporal dementia tend to develop at a later stage of the disease.
Normal Pressure Hydrocephalus
Normal pressure hydrocephalus (NPH) is a type of condition that leads to an accumulation of excess fluid in the ventricles of the brain. These ventricles are spaces filled with fluid that are supposed to help provide cushioning to the brain and spinal cord. The ventricles depend on having just the right balance of fluid in order to function correctly. When the fluid starts to accumulate excessively, it puts a lot of pressure on the brain, which causes damage to the brain cells. This is what causes the symptoms of dementia.(35)
Diagnosis of NPH takes a long time, and the condition is often misdiagnosed as well. In most cases, it takes a lot of diagnostic tests to first rule out other types of dementia. According to research by John Hopkins Medicine, it is estimated that NPH causes just five percent of dementia cases.(36)
Some of the potential causes of this condition may include a brain tumor, infection, bleeding, injury, or previous brain surgeries.
Leaving this condition untreated can cause the symptoms to worsen. Seeking early treatment can help your doctor prevent further brain damage from happening. Unlike other types of dementia, it is possible to cure normal pressure hydrocephalus with surgery.(37)
Also known as Wernicke encephalopathy or Wernicke’s disease, Wernicke-Korsakoff syndrome is a type of brain disorder. This is caused by a deficiency of vitamin B1. The condition causes bleeding in the lower parts of the brain. Wernicke-Korsakoff syndrome causes physical symptoms like loss of muscle coordination, double vision, trouble processing new information, remembering things, or learning new skills. As the disease progresses, the physical symptoms of Wernicke’s disease (especially if the condition is left untreated) start to decrease, and the symptoms of Korsakoff syndrome begin to take over.(38)
Korsakoff syndrome is a type of memory disorder that develops when Wernicke’s disease progresses without treatment. The two conditions are linked, which is why they are typically grouped together as one condition, thus being called Wernicke-Korsakoff syndrome. The symptoms of this syndrome are similar to the other forms of dementia, but the syndrome is unique in that it is a preventable condition, and it is also treatable if treatment is sought at an early stage.(39)
Huntington’s disease is a genetic disease that can cause dementia. There are two types of Huntington’s disease, namely juvenile and adult-onset Huntington’s. Juvenile is a rarer form of the condition, and it causes symptoms in adolescence or sometimes even in childhood. The adult form of Huntington’s disease usually starts to cause symptoms when a person is in their 30s or 40s. The condition leads to a premature breakdown of the nerve cells in the brain, which leads to symptoms of dementia along with impaired movement as the disease progresses.(40)
Difficulty walking, trouble swallowing, and jerking of the muscles are some of the symptoms associated with Huntington’s disease. The dementia symptoms linked to Huntington’s disease are similar to those that are seen in other types of dementia, including anger, depression, and mood changes.(41)
Mixed dementia is a condition where a person is suffering from more than one type of dementia. Mixed dementia is a very common form of dementia, with the most common type being a combination of Alzheimer’s disease and vascular dementia.
According to estimates by the Hersey Alzheimer’s Association, nearly 45 percent of people with dementia are known to have mixed dementia, though they are not aware of it.(42) Mixed dementia causes many different types of symptoms, with some people experiencing symptoms like disorientation and memory loss followed by behavioral and mood changes. Most people with mixed dementia experience difficulty in walking and speaking as the disease advances.
While these are the main types of dementia, it is also important to realize that many health conditions can also cause dementia, especially in the later stages of the disease. For example, people with HIV tend to develop dementia and cognitive impairment in the later stages, especially if they are not on antiviral medications. Even people with multiple sclerosis are also known to develop dementia. No matter what is the cause of your dementia, it is important to know that early treatment can help your condition from worsening. If you suspect that you or a loved one is experiencing symptoms of dementia, it is important to speak to a doctor at the earliest so that your treatment can be started before the condition worsens.
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