Dementia is an umbrella term used to refer to the host of diseases that cause a decline in memory and other mental abilities of an individual. Most conditions and diseases classified under dementia are caused by neurodegenerative changes occurring in the brain, meaning that the brain breaks down over time. These changes tend to affect the daily activities carried out by a person. Some common types of dementia include Alzheimer’s disease, vascular dementia, Lewy body dementia, and mixed dementia.
People commonly associate deteriorating mental capabilities with age. However, the memory loss may not be due to age alone, but instead may be due to underlying dementia, which tends to progress with age.
The most common type of dementia is Alzheimer’s disease, constituting 60-80% of dementia cases. Followed by Alzheimer’s is vascular dementia, which occurs due to blockage in the blood vessels in the brain and micro hemorrhages. The blockage in small blood vessels leads to small vessel ischemic disease, or damage from lack of bloodflow. Several other factors can also cause dementia, such as a deficiency of specific vitamins or thyroid problems.
Types of dementia
- Alzheimer’s Disease
Alzheimer’s disease is a progressive neurodegenerative disorder that can result in significant memory impairment. In saying that it is progressive, this means that it will progress overtime. It is mainly caused by the deposition of a protein that builds up both in and around brain cells. This also leads to the formation of plaques around the brain cells that hinder brain activity. In addition to memory loss, patients in the late stages of Alzheimer’s have speech challenges and difficulty registering their surroundings properly. There are medications in the class “Acetylcholinesterase inhibitors” that can be used to help with some memory loss and behavior changes earlier in the disease process, but they do not stop the underlying neurodegenerative process. In effect, they can delay the course of the disease for a period of time. Although there is no known cure, research is being carried out to look into various therapies to slow down and also to stop the progression of the underlying disease process. Short term memory impairment is one of the first symptoms of Alzheimer’s since it targets the part of the brain that influences memory and learning.
- Vascular Dementia
Vascular dementia is the second most common cause of dementia in the US. As the name suggests, the main cause of vascular dementia is a problem with the blood vessel – either ischemic or hemorrhagic stroke and small vessel ischemic disease – leading to cognitive loss. Stenosis and blockage in brain blood vessels, impaired brain blood circulation, and the brain’s deprivation from vital nutrients could also cause vascular dementia. Alzheimer’s and vascular dementia have many overlapping symptoms, such as cognitive impairment, lack of concentration, difficulty in understanding and communicating, and memory loss. At times, Vascular dementia has a more step-wise course of worsening rather than the more smooth progressive worsening in Alzheimer’s dementia. To prevent vascular dementia, it is important to control vascular risk factors such as high blood pressure, diabetes, high cholesterol and smoking.
Mixed dementia refers to when multiple types of dementia occur simultaneously. The most common type of mixed dementia is that of Alzheimer’s disease, occurring alongside vascular dementia. Since mixed dementia can vary in severity, symptoms also vary depending on which part of the brain has been affected. Many individuals with mixed dementia are often unaware of the exact diagnosis. Therefore, seeing a neuropsychologist and memory disorder specialist can help in making the correct diagnosis.
- Dementia with Lewy Bodies (DLB)
Lewy body dementia is a progressive neurodegenerative disease caused by the deposition of abnormal proteins, called alpha-synuclein, in the brain. The alpha-synuclein clusters result in chemical changes in the brain, leading to symptoms such as abnormal movements, difficulty with thought process, and behavior. Sometimes it is difficult to diagnose this type of dementia since the symptoms overlap with Alzheimer’s and schizophrenia symptoms. The abnormal movements are similar to those in Parkinson disease, and so this is considered a “Parkinson plus” syndrome. Therefore, evaluation by memory disorder and movement disorder specialists can help reach the correct diagnosis.
- Frontotemporal Dementia
Frontotemporal dementia affects the frontal and temporal lobes of the brain, which control language, behavior, and personality. Frontotemporal dementia occurs when either one of these lobes shrinks and does not function properly. Symptoms vary according to the damaged area and can include speech problems or behavioral changes, including disinhibited (or uncontrolled) and socially inappropriate behavior, a decline in empathy, and a dramatic change in eating habits. Symptoms of frontotemporal dementia often begin in late 40s and 50s. The exact cause of this kind of dementia is still unknown.
- Dementia Related to Parkinson’s Disease
Parkinson’s dementia is diagnosed if patients with Parkinson’s disease experience symptoms of dementia after a year of the onset of their motor difficulties. It is characterized by a loss of memory, trouble with concentrating, and difficulty in thinking and learning due to changes in the neurotransmitters in the brain., including dopamine.
- Other “Parkinson Plus” Dementias Cortical Basal Degeneration (CBD) and Progressive Supranuclear Palsy
Corticobasal degeneration is a rare progressive brain disease. It is a neurological abnormality caused by the loss of cells in some regions of the brain. People with the disorder tend to lose motor skills in one part of the body, which eventually spreads to the rest of the body. Initial symptoms include rigidity in the limbs, which prevent the patient from voluntarily moving the leg or arm. Over time, behavioral changes develop. The leading cause of this disease is the loss of brain tissue for unknown reasons. Therapies are conducted for each of the symptoms present.
Progressive Supranuclear Palsy (PSP) is similar to CBD due to the deterioration of certain areas in the brain, in this case involving the brainstem. It leads to imbalance, slowed movement, trouble in moving eyes, and loss of memory. The first symptom is usually a loss of balance.
Unfortunately, the cause behind this disorder is still unknown; it is theorized there may be a genetic component
- Dementia Related to Huntington’s Disease
Huntington’s is a progressive disease that affects a person’s motor abilities. Huntington’s is a genetic condition that begins with trouble in movement. The onset of dementia affects memory as a person is unable to learn new things and loses their sense of judgment. As the disease progresses further, a person’s intellect declines. Huntington’s disease can also affect people’s mental health. Therapies and medications directed towards symptoms can help.
- Dementia Related to Normal Pressure Hydrocephalus
Normal Pressure Hydrocephalus (NPH) is a rare neurological disease that creates trouble in movement and leads to dementia. Due to enlarged ventricles – which are the areas cerebrospinal fluid collects in the brain – this can lead to a triad of difficulty walking with a particular pattern of gait, difficulty controlling urine, and memory changes. Due to its similarity to other neurological disorders, many tests are required to diagnose it, and it often goes undiagnosed. It is thought that part of the brain does not absorb fluid as well as it should and then the ventricles of the brain slowly enlarge to accommodate the extra fluid, restricting blood flow to the frontal and prefrontal lobes. Cognitive functions weaken, and movement is limited with the onset of dementia. Later, concentration levels and motor control decline.
- Rapidly progressive Dementias
- Creutzfeldt-Jakob disease is a rare yet fatal abnormality of the brain that can result in death within a year. Initial symptoms include weak memory, loss of body control, behavioral changes, and blurred vision, which escalate with time and lead to complete loss of memory and blindness. CJD is caused by abnormal forms of proteins in the brain, called “prions.”
- Autoimmune encephalitis refers to conditions that cause the body’s immune system to attack healthy and normal brain cells, resulting in inflammation in the brain. Symptoms include worsening memory, seizures, speech problems, and even coma. There is no precise cause of the disease as it tends to occur suddenly and sporadically. Over the past years, a number of antibodies have been developed that are associated with autoimmune encephalitis, and these can be tested on blood or cerebrospinal fluid.
- Hashimoto’s encephalopathy is a rare disease that is characterized by confusion and seizures. It is caused by a disorder in the immune system that affects the thyroid and the central nervous system. Its cause is yet unknown, with most studies showing inflammation in the body.
- HIV associated dementia (AIDS dementia) is caused by an infection that spreads across the brain and escalates with the symptoms of dementia. The membranes of the brain swell, causing abnormality in brain functions.
- Metabolic causes of rapidly progressive dementias, Wernicke Korsakoff Syndrome (WKS), is caused by a lack of vitamin B1 thiamine, which metabolizes glucose to provide energy for the brain to function. Vitamin B deficiency causes the hypothalamus in the brain to malfunction and leads to memory loss, among other symptoms. It is mainly caused by a high intake of alcohol. If diagnosed early, thiamine can be supplemented, and these symptoms can disappear. If this goes undiagnosed and untreated, it can lead to permanent memory problems.
Dementia is caused by damage to brain cells, which disrupts their functions and impairs their ability to communicate with each other. The brain is divided into different parts, and each part is responsible for a specific action. If any one of these parts is affected, a person faces difficulty in performing that action. For instance, in Alzheimer’s, protein deposits in and around brain cells affect the region that controls memory and learning. In this way, a person first starts losing their memory and then other functions. Dementia can be caused by other factors, as well.
While effects on the memory and thinking functions are often permanent in many types of dementia, those caused by lack of vitamins, thyroid, excessive drinking, depression, and after-effects of medication can be treated and cured. In this way, it is of the utmost importance when a person has memory loss to seek Neurological care so that the cause can be diagnosed.
Signs and Symptoms
All signs and symptoms of dementia vary from person to person, depending on the brain’s affected region. However, some types of dementia share common symptoms, including difficulty in learning new information, confusion, loss of memory, and cognitive disability. Most dementias tend to be progressive, which means that the symptoms exacerbate over time. If dementia is diagnosed from its onset, doctors can provide treatments and therapies to reduce its growth. However, dementia is often disregarded in its early stages due to mild symptoms like weakening memory, getting lost, or forgetting the time. Symptoms increase in the developing stages in which people can forget the way to their own home, need someone to look after them, forget names and events, and even face difficulties in communicating. The late stages are quite severe, with high memory loss and evident signs of dementia. In later stage, more primitive functions can also be impaired, such as those that allow a person to swallow food and water.
There is no simple way of diagnosing dementia. Doctors have to run multiple tests, medical examinations, and complete a thorough physical examination. Additionally, doctors must keep an eye on the day-to-day behavioral changes in people to confirm the presence of dementia.
It can be challenging to diagnose the specific subtype of dementia of which a person may be suffering because the symptoms tend to overlap. To judge the type of dementia, a doctor must observe the pattern of changes occurring in a person and compare what functions a person can and cannot perform. Medical developments have made this work easier, including having some blood tests for identifying causes, such as biomarkers being studied to diagnose Alzheimer’s dementia more easily.
Diagnosing dementia includes cognitive and neuropsychological tests in which thinking skills are reviewed. Then, a neurological evaluation takes place to evaluate speech, memory, balance, and movement. Brain scans such as MRI, CT, and PET are ways of looking at brain activity to find any strokes or protein deposits in the brain. Simple lab tests also play an essential role in the diagnosis since they can show the deficiency of a vitamin or detect a thyroid problem. Finally, at times, a psychiatric evaluation may be necessary to check the mental health of a person.
The treatment of dementia relies upon diagnosing the type of dementia and its cause. Currently, there is no cure for progressive kinds of dementia. Nonetheless, there are certain treatments that can help slow down the process and improve symptoms. Medications may be prescribed to manage dementia symptoms temporarily. Therapies are conducted to control symptoms, such as behavioral and mood changes. Moreover, occupational therapies can help people to adapt to their illness and manage their lives accordingly.
In some reversible types of dementia – such as Wernicke encephalopathy or Hashimoto’s encephalopathy – if the cause is found early and treated, the person can make a full recovery.
With the improvement of technology in the medical field, many studies are being carried out on dementia and its causes. The most challenging part is to diagnose the type of dementia a person is suffering from, with much more research being required in this area. Moreover, the progressive nature of most kinds of dementia limits the use of medical treatment. However, as seen in the case of Alzheimer’s disease, some symptoms can be alleviated and slowed down, adding more years to the patient’s life. Volunteers in clinical research are necessary to improve the study of dementia. Even though we associate dementia with memory loss and senility, there is much more to it. As new types of dementia and symptoms are showing up in people, more research and studies are being carried out to gauge the right kinds of treatment for them.
Most common causes of dementia
Dementia Fact Sheet
Diagnosis & Treatment by Mayoclinic
Types of Dementia by WebMD
Creutzfeldt Jakob Disease Factsheet
Complex or HIV associated Dementia
Consciousness, Seizures & Myoclonus
Wernicke Korsakoff Syndrome
Lewy Body Dementia by Mayoclinic
Dementia Resources by Parkinson.org