What is dementia?
Dementia is a condition where the mental processes are impaired to the point that it affects normal activities of daily life. Other features for that need to be considered in the definition of dementia is :
- lasting for six months or longer,
- not present since birth, and
- not associated with a loss of consciousness.
It is often that dementia is simply a matter of memory loss but the condition extends beyond poor memory, and the decision making and reasoning processes are also affected. Dementia is not a single disease but rather a syndrome. Even though it is common in the elderly, the associated features of dementia are not a normal part of the aging process and it is more serious than forgetfulness in the senior years. Dementia is largely irreversible. It gets worse with age and the quality of life gradually deteriorates.
Other Names for Dementia
Dementia is known by various common terms. Many of these names are inappropriate and used quite loosely for a range of behavior that is not considered the norm. This includes :
- Mental deterioration
- Mental decay
However, it is important to note that dementia is a medical disorder and the patient does not have control over their mental faculties or loss thereof.
Types of Dementia
There are different types of dementia classified according to the underlying cause, mechanism of the causative disease and characteristic symptoms.
This is an outdated term that was earlier used to describe dementia as a natural outcome of aging in the elderly. However, it is now known that in most cases there is some underlying disease cause of dementia in the elderly.
Alzheimer’s disease is the leading cause of dementia. The exact cause of this neurodegenerative disease is still unclear but the brain of Alzheimer’s patients displays characteristic sticky masses of proteins within it.
Vascular dementia occurs when the blood supply to the brain is interrupted as is seen with a stroke or similar disorders. This damages the brain tissue and may even lead to cell death either in large areas or multiple small areas.
Dementia with Lewy bodies (DLB)
Lewy bodies are abnormal, spherical masses of proteins that cause death of nerve cells in brains of DLB patients. The exact correlation with dementia is not clear but it has been found to be present in the brains of Alzheimer’s and Parkinson’s disease.
Also known as Pick’s disease, this is a rare type of permanent dementia. There is abnormally large amount of a protein known as tau, or an abnormal variation of this protein. There appears to be some genetic factors associated with this type of dementia.
Untreated syphilis can progress to the tertiary stage which may lead to dementia. However, the availability of penicillin has ensured that the disease is treated in the very early stages thereby avoiding these complications.
Creutzfeldt–Jakob disease dementia
Creutzfeldt–Jakob disease (CJD) is a rapidly progressive form of dementia. It is sometimes commonly referred to as mad cow disease. It is believed to be transmitted by a type of protein known as a prion, which is not a virus as such. Sometimes genetic disorders can cause production of these proteins.
Other types of dementia
Dementia may be seen with various other diseases. Here dementia may not always occur but does arise at times as a complication. This includes :
- Parkinson’s disease dementia
- Huntington disease dementia
- HIV-associated dementia
Dementia Brain Changes
There is no specific change in the brain that occurs for all types of dementia. It is dependent on the underlying disease. Death of brain tissue is seen with vascular dementia. These areas are known as infarcts. In Alzheimer’s disease there is a build up of protein plaques (amyloid) and twisted massed of proteins (neurofibrillary tangles) within the nerve cells of the brain. These changes may eventually disrupt the electrical signals and chemical messengers (neurotransmitters) in the brain but mainly cause death of the neurons (nerve cells). The millions of connections among nerves which are responsible for the brain function are therefore disrupted or lost. It is these connections that are normally responsible for memory, decision making and rational thinking.
Many factors that cause the death of neurons in the brain contribute to dementia. The main causative factors that contribute to permanent and progressive dementia includes :
- Brain injuries sustained by a blow like during an assault or accident, stroke, infection or raised pressure on the brain.
- Brain tumors which may be either benign (non-cancerous) or malignant (cancerous)
- Neurodegenerative diseases which vary in mechanism and includes conditions like in Parkinson’s disease and Alzheimer’s disease.
- Genetic factors which may contribute to the development of certain diseases linked to dementia.
There are other conditions and risk factors that may contribute to dementia although this may not be severe like in the diseases above, progressive or permanent. It often resolves once the underlying disease is treated or the risk factor removed.
- Severe psychological stress, depression and anxiety
- Chronic alcoholism (alcohol dementia or alcoholic psychosis)
- Abnormalities in blood glucose control as is seen with uncontrolled diabetes mellitus.
- Acute infections like encephalitis.
- Thyroid disorders.
- Illicit drug use.
- Prescription medication.
- Nutritional deficiencies.
The symptoms of dementia extend beyond forgetfulness. Many other areas of mental functioning are affected in dementia. These may include, but are not limited to, language, perception, emotions, reasoning, learning and memory. The warning signs are lapses in routine activities like misplacing things and having problems in maintaining regular schedules. The progress of dementia can be classified into three phases:
Forgetfulness is the first apparent symptom but it is often taken to be a sign of developing age and therefore ignored. More symptoms gradually appear and the affected persons might find it difficult to navigate even the most familiar routes. Learning anything new suddenly seems very difficult and there are subtle changes in terms of behavior, personality and social skills. The naming of familiar objects takes undue effort and a loss of interest in things and people often follows. Some patients start experiencing troubled sleep in this phase.
In advanced stages, dementia renders patients incapable of taking care of themselves. The early phase symptoms worsen, making it all the more difficult to name objects, write or recall things. A sense of confusion prevails and hallucinations and delusions are common. Depression strikes and there is a gradual decline in the ability to judge even the simplest of situations. Everyday chores like cooking, driving and dressing become difficult and tiresome. There are small periods of loss of awareness about oneself and this symptom becomes severe with time.
In the most severe cases, people are unable to recognize family members and friends. Comprehension becomes very difficult. By this stage, the person is unable to perform even the most basic activities of life, such as eating, bathing, and dressing on their own.
Different diagnostic tests are available for dementia. Most of these assess a person’s cognitive abilities. In addition, brain imaging techniques can also be used to check the underlying changes in brain structure. Nutritional deficiencies, infections or abnormal metabolite levels can be also detected by routine laboratory tests.
Mini mental state examination (MMSE) is the most frequently used cognitive test that checks the participant’s orientation to the time and place of the test, repetition, registration and recall abilities, basic mathematical and motor skills and the use of language. Patients are categorized as suffering from severe, moderate or mild dementia depending on specific ranges within which their test scores fall.
Blood samples of patients are checked for the presence of any infections, alcohol content, dementia-inducing drugs or deficiencies in vitamin B12 and folic acid. Alteration in the levels of thyroid-stimulating hormone (TSH), electrolytes, calcium, liver enzymes, and kidney function can also be indicative of metabolism-induced dementia.
Brain imaging techniques
Various imaging techniques like CT scan, PET scan or MRI scan can be used to indicate the presence of stroke, a cause of vascular dementia.
Treatment of Dementia
Behavioral therapy is frequently recommended for dementia patients. Though nutritional deficiency-induced or metabolism-induced dementia can be reversed by proper treatment, other forms of dementia are largely irreversible and incurable. Many medical practitioners prescribe anti-depressants and anti-psychotic drugs but there is little scientific evidence supporting their effectiveness. Some medications help by providing symptomatic relief to some degree. This includes :
- Acetylcholinesterase inhibitors help to increase the level of the neurotransmitter acetylcholine by blocking its breakdown. It may be of some benefit for dementia in Alzheimer’s disease and can also be helpful for vascular dementia and in Parkinson’s disease dementia.
- NMDA receptor blockers prevent glutamate from attaching to NDMA receptors in the brain which can affect signals along the nerves. It may be used in conjunction with acetylcholinesterase inhibitors.
However, no medication has as yet been shown to reverse the changes in the brain or reverse dementia.
Article reviewed by Dr. Greg. Last updated on May 25, 2012