Dementia is not a specific disease. It is a descriptive term for a collection of symptoms that can be caused by a number of disorders that affect the brain. People with dementia have significantly impaired intellectual functioning that interferes with normal activities and relationships. They also lose their ability to solve problems and maintain emotional control, and they may experience personality changes and behavioral problems such as agitation, delusions, and hallucinations. While memory loss is a common symptom of dementia, memory loss by itself does not mean that a person has dementia. Doctors diagnose dementia only if two or more brain functions – such as memory, language skills, perception, or cognitive skills including reasoning and judgment – are significantly impaired without loss of consciousness.
There are many disorders that can cause dementia. Some, such as AD, lead to a progressive loss of mental functions. But other types of dementia can be halted or reversed with appropriate treatment.
With AD and many other types of dementia, disease processes cause many nerve cells to stop functioning, lose connections with other neurons, and die. In contrast, normal aging does not result in the loss of large numbers of neurons in the brain.
What Are the Different Kinds of Dementia?
Dementing disorders can be classified many different ways. These classification schemes attempt to group disorders that have particular features in common, such as whether they are progressive or what parts of the brain are affected. Some frequently used classifications include the following:
- Cortical dementia: dementia where the brain damage primarily affects the brain’s cortex, or outer layer. Cortical dementias tend to cause problems with memory, language, thinking, and social behavior.
- Subcortical dementia: dementia that affects parts of the brain below the cortex. Subcortical dementia tends to cause changes in emotions and movement in addition to problems with memory.
- Progressive dementia: dementia that gets worse over time, gradually interfering with more and more cognitive abilities.
- Primary dementia: dementia such as AD that does not result from any other disease.
- Secondary dementia: dementia that occurs as a result of a physical disease or injury.
Dementia is a term that describes a collection of symptoms that include decreased intellectual functioning that interferes with normal life functions and is usually used to describe people who have two or more major life functions impaired or lost such as memory, language, perception, judgment or reasoning; they may lose emotional and behavioral control, develop personality changes and have problem solving abilities reduced or lost.
There are different classification schemes for dementias roughly based (and with overlap) on observed problems; some frequently used are cortical (memory, language, thinking, social) , subcortical (emotions, movement, memory), progressive (cognitive abilities worsen over time), primary (results from a specific disease such as Alzheimer’s disease and secondary (occurs because of disease or injury).
Alzheimer’s disease (AD): is the most common cause of dementia in people over age 65 with cause possibly related to amyloid plaques and neurofibrillary tangles; almost all brain functions, including memory, movement, language, judgment, behavior, and abstract thinking, are eventually affected.
Vascular dementia: is the second most common cause of dementia caused by brain damage from cerebrovascular or cardiovascular problems (strokes) or other problems that inhibit vascular function; symptoms similar to AD but personality and emotions effected only late in the disease.
Lewy body dementia: is common and progressive where cells in the brain’s cortex die and other contain abnormal structures (Lewy bodies); symptoms overlap with Alzheimer’s disease but also include hallucinations, shuffling gait, and flexed posture with symptoms that may vary daily.
Frontotemporal dementia: is dementia linked to degeneration of nerve cells in the frontal and temporal brain lobes and some evidence for a genetic factor (many have a family history of the disease); symptoms in patients (usually ages 40 – 65) have judgment and social behavior problems such as stealing, neglecting responsibilities, increased appetite, compulsive behavior and eventual motor skill problems and memory loss.
HIV-associated dementia: is due to infection of the brain with HIV virus; symptoms include impaired memory, apathy, social withdrawal, and concentration problems.
Huntington’s disease: is a heredity disorder caused by a faulty gene and children of a person with the disorder have a 50% chance of getting the disease; symptoms begin in 30-40 year old people with personality changes such as anxiety, depression and progress to show psychotic behavior severe dementia and chorea – involuntary jerky, arrhythmic movements of the body.
Dementia pugilistica: is also termed Boxer’s syndrome, is due to traumatic injury (often repeatedly) to the brain; symptoms commonly are dementia and parkinsonism (tremors, gait abnormalities) and other changes depending where brain injury has happened.
Corticobasal degeneration: is a progressive nerve cell loss in multiple areas of the brain; symptoms begin at about age 60 on one side of the body and include poor coordination and rigidity with associated visual-spatial problems that can progress to memory loss, hesitant speech and dysphagia (difficulty swallowing).
Creutzfeldt-Jakob disease: is a rare disease that seems related to a gene mutation that causes rapid (death about one year after symptoms begin to develop) degenerative and fatal brain disease in people usually over 60 years old; personality changes and reduced coordination develop, rapidly followed by impaired judgment and vision and many patients develop a coma before they die.
Other rare hereditary dementias: Most of these diseases develop in people between 50 – 60 years old and most have variable symptoms of poor reflexes, dementia, hallucinations, paralysis and most develop coma before death; some of the names of these diseases are Gerstmann-Straussler-Scheinker disease, familial British dementia, familial Danish dementia and fatal familial insomnia.
Secondary dementias: These dementias occur in patients with other disorders of movement such as Parkinson’s disease or multiple sclerosis and may because by one or more problems listed above; these dementias may share symptoms with any of the above mentioned dementias but researchers are unsure if this is due to disease overlap or other causes.
Dementias in children: While infections, trauma and poisoning can lead to dementia in both children and adults, there are some dementias that are unique to children but may result in mental problems, seizures, reduction or loss of motor skills, blindness, neurodegeneration and death; many are inherited disorders such as Niemann-Pick disease, Batten disease, Lafora disease and mitochondrial abnormalities.
Other conditions that may cause dementia: Reactions to medications, endocrine and metabolic problems, nutritional deficiencies, infections, subdural hematomas, poisoning, brain tumors, anoxia (lack of oxygen), heart and lung problems.
What conditions are not dementia: Although these conditions may resemble some aspects of dementia, they have different causes, usually are treatable and have better outcomes; examples are depression, delirium, mild cognitive impairment and age-related cognitive decline.
Dementia Facts – causes: All causes of dementia result from death and damage of nerve cells in the brain; genetics and possibly the formation of different types of inclusions in the brain cells are likely the major causes, although some researchers suggest that certain inclusions may be only side effects of an underlying disorder.
Risk factors for dementia include advancing age, genetics (family history), smoking, alcohol use, atherosclerosis, high cholesterol, diabetes, high plasma homocysteine levels, mild cognitive impairment, Down syndrome.
Dementia is diagnosed by using many methods such as patient’s medical and family history, physical exam, neurological evaluations, cognitive and neuropsychological testing, CT’s, MRI’s and other brain scans, mental status exams, electroencephalograms, blood tests, psychiatric evaluations, and even some pre-symptomatic tests are available for some patients that may have a genetic link to dementia.
Most treatments for dementia will neither reverse or stop the disease; however, there are treatments and medications that may reduce the symptoms and slow the disease progression; they are tight glucose control by persons with diabetes, intellectual stimulating activities, lowering cholesterol and homocysteine levels, regular exercise, education, controlling inflammation of body tissues, using NSAID’s and possibly other medications.
*Dementia facts medical author : Charles P. Davis, MD, PhD
