Dementia is a permanent decline in brain function, usually memory and thinking. Dementia is caused by damage to nerve cells in the brain.
Most people experience some degree of memory loss in older age; however, in a person with dementia, memory loss becomes so severe that it has a serious effect on their daily life.
The human brain.
The basic cell of the nervous system. A specialized cell that generates and transmits nerve impulses.
Brain damage can take many different forms and have many different causes. The most common types of dementia are:
Alzheimer's disease is the most common type of dementia.
Although the exact cause of this condition is not understood, it is known that proteins called amyloid and tau build up in the brains of people with Alzheimer's disease. It is thought that this impairs the normal function of the brain, eventually leading to the death of brain cells.
Alzheimer's disease is progressive: its symptoms can appear and gradually become more serious over time. It can sometimes take a long time before the symptoms are noticed.
Some of the more common symptoms of Alzheimer's disease include:
Vascular dementia is one of the most common types of dementia. The symptoms of vascular dementia can appear either suddenly after a major stroke, or gradually after multiple small strokes.
The cause of vascular dementia is reduced flow of blood to the brain and brain injury.
The symptoms of vascular dementia may be similar to those of Alzheimer's disease, but may also include:
Lewy body dementia is a common type of dementia that has similar symptoms to both Alzheimer's disease and Parkinson's disease. Lewy bodies are small deposits of protein that build up inside nerve cells of the brain.
The symptoms of Lewy body dementia may vary, according to the region of the brain the protein accumulates in. People with Lewy body dementia are less likely to experience the short-term memory loss experienced with Alzheimer's disease.
Some of the more common symptoms of Lewy body dementia may include:
Some other common medical conditions that may cause dementia include:
Parkinson's disease occurs as a result of damage to the cells that produce dopamine, which reduces the amount of dopamine in the brain. Dopamine is an important molecule involved in movement, decision-making and planning.
As Parkinson's disease progresses, memory and reasoning gradually decline, leading to dementia.
Frontotemporal lobar degeneration occurs when abnormal deposits of proteins lead to nerve cell damage in the frontal and temporal lobes of the brain. The frontal and temporal lobes control planning and judgement, emotions and understanding speech. Degeneration of these areas leads to a diverse group of conditions known as frontotemporal dementia. These are marked by changes in personality, impulsive behavior, lack of emotions, and/or difficulties with language. These conditions are not common, and cause dementia at a younger age, particularly between 50-60 years of age.
In Huntington's disease, a defective gene leads to abnormal production of a protein called huntingtin. when this protein builds up in the brain, it damages the brain cells responsible for controlling movement, behavior and thinking.
Huntington's disease dementia is marked by difficulties with thinking, in addition to abnormal jerky movements and psychiatric symptoms ranging from antisocial behavior to depression, mania or psychosis.
With alcohol-related dementia, it is unclear whether alcohol is directly toxic to nerve cells in the brain, or whether the damage to the cells is caused by the reduction of vitamin B1 (thiamine). This vitamin is important for normal brain function.
The symptoms of alcohol-related dementia vary between individuals, but commonly include personality changes, memory problems and confusion. Occasionally, some individuals have a characteristic symptom of imagining and sharing stories of things that they believe happened. This is known as 'confabulation'.
Creutzfeldt-Jakob disease is a rare and fatal condition. It is believed to be caused by prions, which are proteins that can have both a harmless normal form and an infectious form, which can cause disease.
The structure of the infectious form of a prion causes damage to nerve cells in the brain. This leads to a rapid decline in thinking, reasoning and muscle coordination.
Severe traumatic brain injury can result in bleeding and damage to neurons within the brain. Such damage can lead to permanent impairment in thinking and learning.
Some people may have symptoms that mimic dementia, but are related to other conditions such as depression and/or delirium. Depression is more than a low mood; it can also cause problems with concentration, difficulties with memory and thinking, reduced motivation and sleep difficulties. Because of this overlap in symptoms with dementia, telling these two causes apart can often be difficult. However, when the symptoms are due to depression, effective treatment for depression can often resolve these symptoms.
Delirium is generally an acute shift in mental function that can have numerous possible causes, such as:
Many of these conditions will improve with treatment and the delirium associated with them may be reversible, if significant brain cell damage has not yet occurred.
A type of dementia that is due to chronic, excessive consumption of alcohol.
A deficiency in red blood cells or hemoglobin in the body.
A rare and fatal degenerative disease that affects the brain. It is caused by an infectious agent and related to bovine spongiform encephalopathy, also known as 'mad cow disease'.
A mental state caused by temporary disturbances in brain function and characterized by a host of symptoms that may include fluctuating confusion, restlessness, excitement, incoherence, illusions, anxiety, and attention deficit.
A chemical messenger that acts as a neurotransmitter in the brain and a hormone outside the central nervous system. In the brain, dopamine plays a role in motor control and reward-motivated behavior. Outside the brain, dopamine acts across several parts of the body as a local chemical messenger.
A hereditary condition caused by a faulty gene that leads to increased levels of a defective huntingtin protein within nerve cells. This protein causes changes in the central part of the brain, which affects muscle coordination, impairs cognition and causes changes in behavior.
A feeling of boundless energy and positive mood that can lead to uncharacteristic behaviors such as risk-taking, spending excessive amounts of money and saying or doing outrageous things.
The basic cell of the nervous system. A specialized cell that generates and transmits nerve impulses.
An inability to move or feel; a loss of muscle function or sensation.
1. One of the three macronutrients in foods that supply the body with energy. Food rich in proteins include meats, legumes and dairy foods. 2. Large molecules, such as antibodies and albumin, that are found in the blood.
An abnormal mental state characterized by a loss of contact with reality.
A protein molecule that help stabilize cells of the central nervous system, especially neurons.
A large gland located in the lower front part of the neck that produces hormones that regulate metabolism, growth and development, especially during childhood.
A number of complex protein substances that, in certain diseases, are deposited in organs such as the kidneys, spleen and liver.
Vitamin B1, which is required for the metabolism of carbohydrates.
Risk factors for dementia include:
A class of diseases that involves the dysfunction of the heart and/or the blood vessels.
A type of fat produced by the body that is necessary for metabolism.
A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterized by high blood sugar levels. Also known as diabetes mellitus.
A hereditary condition caused by a faulty gene that leads to increased levels of a defective huntingtin protein within nerve cells. This protein causes changes in the central part of the brain, which affects muscle coordination, impairs cognition and causes changes in behavior.
The symptoms of dementia, their severity and their progress vary depending on the type of dementia and the region of the brain that is affected.
The most common signs of dementia are significant problems in memory, language and the ability to carry out complex tasks. People with dementia can also show changes in behavior and social functioning.
At first, dementia usually appears as forgetfulness. Other common symptoms associated with dementia may include:
Patients with dementia can also experience:
A mental state in which a person holds on to a belief despite clear evidence to the contrary.
A state where someone is unable to distinguish reality from hallucination or delusion.
A false perception of something that is not actually there. The perception can be visual or aural.
To help make an accurate diagnosis of dementia, a healthcare provider will:
To eliminate other potential causes of confusion and behavior that can mimic dementia, the following laboratory tests may be performed:
Brain imaging, including computerized tomography (CT) and magnetic resonance imaging (MRI) scans, may be used to diagnose dementia. These scans provide different kinds of images of the brain. The CT scan uses X-rays to produce a 3D image of the brain, while the MRI uses a magnetic field. The scans:
In patients with atypical symptoms, such as those of younger age or with rapidly progressive dementia, a more extensive evaluation may include lumbar puncture, electroencephalogram (EEG), broader blood tests and, rarely, brain biopsy.
A deficiency in red blood cells or hemoglobin in the body.
A chemical element, important for many biological functions. Particularly central to maintaining bone and tooth health.
A test to record the electrical activity of the brain, commonly in a person who suffers from seizures, by placing electrodes on multiple areas of the scalp.
A blood test that measures the rate of red blood cell sedimentation at the bottom of a test tube, which is an indicator of the level of inflammation in the body.
A blood test that examines the blood, either by using a microscope or an automated machine, to determine the number of red blood cells, white blood cells and platelets.
A simple sugar found in many foods (such as fruit) that functions as a major energy source for the body.
The extensive network of cells and structures that is responsible for activating and coordinating the body's functions, sensory input and cognition.
Acute lung inflammation, caused by bacterial or viral infection, primarily affecting the tiny air sacs known as alveoli.
An illness caused by inflammation throughout the body in response to an infection. It can be life-threatening if it leads to septic shock, a dramatic loss of blood pressure.
A chemical element and important micronutrient in the diet. It is present in salt and plays an important role in how the body controls blood pressure.
A large gland located in the lower front part of the neck that produces hormones that regulate metabolism, growth and development, especially during childhood.
A growth caused by an abnormal and uncontrolled reproduction of cells.
A scan that uses ionizing radiation beams to create an image of the body’s internal structures.
A procedure that uses a needle to collect a sample of cerebrospinal fluid, which is the clear fluid surrounding the brain and spine, from the lower back (lumbar region) for analysis. It can also be performed to remove any excess fluid or to deliver medications.
A water-soluble vitamin needed for protein and DNA synthesis, metabolism of folate and red blood cell production.
The treatment for dementia depends on its cause and severity. Generally, there is no cure, but early diagnosis and management can improve the quality of life for the person with dementia.
Treatment of people with dementia is focused mainly on supporting them and their family, and cautiously using medications when appropriate.
Creating a supportive and safe environment for a person with dementia is an important part of treatment. Households should be clutter-free and organized, to remove hazards and maintain order. Following a daily schedule and/or using a checklist creates a habit of ensuring that daily activities are completed.
Regular exercise, such as 30-minute walks, improves mood, promotes restful sleep and maintains overall health. Exercise may need to be supervised, depending on the severity of the dementia, to prevent wandering and/or injury.
Promoting a high-calorie diet and plenty of water helps to overcome the malnutrition and dehydration that can occur with moderate to advanced dementia, as the person forgets to or loses interest in eating and drinking. Also, a high-fiber diet with plenty of fluid and exercise can help prevent constipation, which is a common problem in people with dementia.
Seeing a doctor to simplify medication regimens, such as eliminating unnecessary medications, reducing to once-daily dosing and/or organizing medications into easy-to-take packaging, can help to improve compliance.
Supporting and caring for a person with dementia can be a very difficult and demanding task. Commonly, as the dementia advances and symptoms worsen, providing the physical and emotional support can overwhelm carers. There are services available for carers and families of people with dementia that can provide assistance. It is important to seek help from such services and/or a doctor early, before facing any difficulties. Occasionally, the care needs for a person with dementia may overwhelm what a carer can provide, and/or limit the person's independence at home, which leads to the often difficult decision to place the person with dementia into a care facility. These facilities are well-established to care for such people and provide a comprehensive, caring environment with nurses, doctors and other healthcare professionals.
For some types of dementia, specific medications can help slow the progression of memory decline. These medications do not cure the condition, but help to improve the quality of life. Like all medications, they need to be used with caution, as their side effects can potentially worsen the person's symptoms.
These specific medications are mainly indicated for people with Alzheimer's disease, at varying stages of their condition. The medications fall into two broad categories:
Other medications can occasionally be used to treat accompanying symptoms of dementia, such as:
A compound found in both the central nervous system and the peripheral nervous system that is involved in the transmission of signals between nerves.
Medication used to treat depression and other mood disorders.
The state of insufficient hydration; excessive loss of water; requiring more water in order to function normally.
Passing watery stools in large volumes. Liquid feces and/or frequent stools.
A condition in which a person does not receive the right amount of nutrients such as vitamins, minerals and proteins.
A sensation of sickness and unease, typically felt in the stomach, often accompanied by the urge to vomit. Nausea is a common symptom with many possible causes.
Chemicals that communicate signals from one nerve cell to another, or from nerve cells to other tissues.
A state where someone is unable to distinguish reality from hallucination or delusion.
A chemical produced by the pineal gland in the brain that prepares the body for sleep. It is also available as a medication to help treat sleeping disorders.
People with dementia usually do not die from dementia itself, but from its associated complications. Late stages of dementia, especially Alzheimer's disease, are associated with frequent bouts of pneumonia and this is often the cause of death.
Other complications may include:
More severe stages of dementia may be associated with urinary incontinence. The weaker flow of urine and lower likelihood of completely emptying the bladder increase the risk of developing a urinary tract infection. Also, treatment for urinary incontinence may include the insertion of a urinary catheter, which is known to increase the risk of contracting a urinary tract infection. Urinary tract infections can lead to other serious and fatal complications, including sepsis and multi-organ failure.
The mobility problems and disorientation that is associated with some forms of dementia may increase the likelihood of falls. Falls can cause fractures or head trauma, and the lengthy period of immobilization required for recovery from these injuries can lead to further complications such as thromboembolism and pneumonia.
People with more severe dementia may experience considerable malnutrition, which may lead to weight loss, impaired immune system, loss of muscle tone and the loss of independence.
A condition in which a person does not receive the right amount of nutrients such as vitamins, minerals and proteins.
Acute lung inflammation, caused by bacterial or viral infection, primarily affecting the tiny air sacs known as alveoli.
An illness caused by inflammation throughout the body in response to an infection. It can be life-threatening if it leads to septic shock, a dramatic loss of blood pressure.
Formation of a blood clot, which then dislodges to obstruct a blood vessel further down the circulation.
The outlook for dementia depends on its cause, and the prognosis can also vary according to the individual. If the symptoms mimicking dementia are caused by nutritional deficiencies or an infection, appropriate treatment may achieve a full recovery. For those with vascular dementia, the deterioration of memory may remain stable for years after the initial stroke and treatment may help reduce the likelihood of having further strokes. For other causes of dementia including Alzheimer's disease, Parkinson's disease, Creutzfeldt-Jakob disease, frontotemporal lobar dementia and Huntington's disease, medication may help reduce the rate of disease progression; however, the condition will gradually become worse and lead to its terminal stage. The time over which a condition progresses to its terminal stages may vary widely, ranging from several months to several years.
A rare and fatal degenerative disease that affects the brain. It is caused by an infectious agent and related to bovine spongiform encephalopathy, also known as 'mad cow disease'.
A hereditary condition caused by a faulty gene that leads to increased levels of a defective huntingtin protein within nerve cells. This protein causes changes in the central part of the brain, which affects muscle coordination, impairs cognition and causes changes in behavior.
Although the causes of some types of dementia are yet to be clearly understood, the likelihood of developing dementia may be decreased by:
There is yet no conclusive evidence that mental training or brain games can help prevent or delay the onset of dementia.
Relating to the heart and blood vessels.
A type of fat produced by the body that is necessary for metabolism.