Memory and irreversible dementia
After eliminating other causes of memory loss, physicians will consider irreversible dementias as possible diagnoses.
After Alzheimer's disease, the most common cause of memory loss is vascular dementia--a disorder often resulting from a series of tiny strokes (known as infarcts) that destroy brain cells. Each infarct may be so small that it is inconsequential alone; however, the cumulative effect of many infarcts can destroy enough brain tissue to impair memory, language, and other intellectual abilities. Symptoms often develop suddenly and involve other brain functions: Loss of bladder or bowel control (incontinence), a mask-like facial expression, and weakness or paralysis on one side of the body are thought to be noncognitive hallmarks of vascular dementia. Vascular causes account for 10 to 20 percent of dementia cases.
Other causes of vascular dementia include lupus and other collagen-vascular diseases (these may be at least partially reversible) as well as a major stroke. Many people suffer from vascular dementia as a result of chronic high blood pressure, diabetes, or coronary heart disease (a narrowing of the coronary arteries that jeopardizes the supply of blood to the heart). People who survive a cardiac arrest can also suffer from memory deficits.
Dementia with Lewy Bodies accounts for 5 to 15 percent of cases of dementia. Researchers are uncertain whether it is a type of Alzheimer's or Parkinson's disease or is, in fact, a separate condition. Regardless, proper diagnosis and treatment can help relieve symptoms and slow cognitive loss.
Frontotemporal dementia is much less common than Alzheimer's disease and accounts for 5 percent of cases of dementia. It affects men and women equally, usually starting between the ages of 40 and 65. It has several forms and probably several causes, but personality changes or problems with language are usually the earliest symptoms.
Pick's disease is responsible for approximately one third of cases of frontotemporal dementia. Symptoms associated with Pick's disease include impaired initiation of plans and goal setting, personality changes, unawareness of any loss of mental function, and language difficulties (aphasia). Palilalia--compulsive repetition of a word or phrase with increasing rapidity--sometimes occurs later in the illness. The course of the disease can vary from 2 to 10 years, but its final result is death.
Recent studies suggest that five other neurological diseases that can cause dementia--corticobasal ganglionic degeneration, hippocampal sclerosis, motor neuron disease inclusion dementia, primary progressive aphasia, and progressive supranuclear palsy--have pathological similarities to frontotemporal dementia.
Huntington's disease is a rare hereditary disorder of the central nervous system characterized by uncontrollable movement and dementia. The illness begins gradually, usually between the ages of 30 and 40, and people can live with the disease for up to 20 years. Early signs of Huntington's disease include changes in behavior and unusual, fidgety movements. Eventually, however, twisting and jerking movements that spread to the entire body are followed by memory loss, confusion, and hallucinations.
Huntington's disease directly affects the parts of the brain that control coordination. In 1993, scientists identified the gene defect believed to cause Huntington's disease. The gene is dominant, meaning that children with a parent who carries the defective gene have a 50 percent chance of developing Huntington's disease. The discovery raises the possibility that a therapy may be developed to correct the defective gene, though currently no treatment is available.
Creutzfeldt-Jakob disease (CJD) is a rare, fatal brain disorder that causes a rapidly progressing dementia. The disease affects approximately 1 in 1 million people worldwide each year, including 250 to 300 Americans. It can be transmitted through infected tissue (usually transplants), be inherited, or occur with no known explanation. It typically strikes people between the ages of 50 and 70 and leads to death within a few months. A disorder with similar symptoms appeared in England in the mid-1990s, approximately 10 years after an outbreak of bovine spongiform encephalopathy (mad cow disease) in cattle that was linked to feed that included infected animal tissue. The disorder in humans was named new variant CJD (vCJD). It has been reported in about 150 people worldwide, most of whom have been younger than age 30. The disorder progresses more slowly than classic CJD (about 14 months) but inevitably leads to death.
People with amnestic syndrome (amnesia) demonstrate severe memory loss but otherwise have normal intelligence. Amnesia is caused by damage to the temporal lobes resulting from an accident, severe alcoholism, prolonged low blood pressure, or viral inflammation of the brain. Brain damage from such injuries usually results in anterograde amnesia, an inability to remember anything occurring after the injury. Retrograde amnesia, a loss of memory from a time prior to the accident--such as during childhood --is uncommon.
Alzheimer's disease is a progressive disorder of the brain characterized by deterioration of mental faculties owing to the loss of nerve cells and the connections among them. Our Alzheimer's guide has more on this condition.
