The cause of dementia may be vast and some are often difficult to tell apart. Many conditions, such as metabolic diseases (which include hypothyroidism or anemia); nutritional deficiencies (such as B12 deficiency or Folate deficiency); strokes or head injuries, may cause dementia symptoms, especially in older people.
All forms of dementia, no matter what the cause, represent injury to the brain tissue itself. When the brain tissue injury can be stopped or reversed, the dementia symptoms may stop or be reversed, if no permanent damage has been done.
The Most Common Irreversible Causes of Dementia:
- Alzheimer disease: This is, by far, the most common cause of dementia, accounting for well over half of all cases (some statistics report it as high as 80%). Alzheimer disease is considered to be at least partly hereditary, due to the fact that it tends to run in families. (Please note that just because a relative has Alzheimer disease, it does not mean that another family member automatically get the disease.) In this disease, abnormal protein is deposited in the brain and destroys cells in the areas of the brain that control memory and mental functions. People with Alzheimer disease also have lower-than-normal levels of neurotransmitters or ‘brain chemicals’ that go to other areas of the brain that control important brain functions. Alzheimer disease is not reversible, and no known cure exists. We do, however, have medications that can slow its progression.
- Vascular dementia: This is the second most common cause of dementia, accounting for as many as 30-40% of cases. This dementia is caused by “hardening of the arteries” (the medical term is atherosclerosis) in the brain. In essence, there are deposits of fats, dead cells, and other debris that form on the inside of arteries, partially (or completely) blocking the blood flow to a particular area of the brain. These blockages cause multiple strokes,(sometimes referred to as mini-strokes) or interruptions of blood flow to the brain. Because this interruption of blood flow is known medically as “infarction,” this type of dementia is sometimes called multi-infarct dementia. Vascular dementia is related to high blood pressure, high cholesterol, heart disease, diabetes, and other related conditions. Treating these conditions can slow the progress of vascular dementia, but functions do not come back once they are lost.
- Lewy body dementia: This is caused by very small, abnormal deposits of protein, called Lewy bodies, and in essence, destroy nerve cells in certain areas of the brain. These deposits can cause symptoms typical of Parkinsons disease, such as tremor and muscle rigidity, as well as dementia which is similar to Alzheimer disease. Lewy body dementia affects thinking, attention, and concentration more than memory and language. Like Alzheimer disease, Lewy body dementia is not reversible and has no known cure. The drugs used to treat Alzheimer disease usually do not benefit most people with Lewy body disease, and in some cases, have the opposite desired effect.
- Frontotemporal Dementia (aka Pick’s Disease): This is a form of dementia that is similar to Alzheimer’s disease, except that it tends to affect only certain areas of the brain, (primarily the frontal lobe, thus the name frontotemporal). People with Frontotemporal Dementia have abnormal substances (called Pick bodies and Pick cells) inside nerve cells in the damaged areas of the brain. These Pick bodies and Pick cells have an abnormal amount of a protein called tau that causes the damage. Symptoms such as behavior changes, speech difficulty, and impaired thinking occur slowly, but continue to get worse. The early personality changes can help doctors tell Frontotemporal dementia apart from Alzheimer’s. (Memory loss is often the main, and earliest, symptom of Alzheimer’s.) The changes in behavior continue to get worse and are often one of the most disturbing symptoms of the disease. Anger and inappropriate behavior in social settings is often considered a hallmark of Frontotemporal dementia. Some patients will have more obvious difficulty with decision making, complex tasks, or language (trouble finding or understanding words or writing). Families are often faced with abrupt behavior changes for no reason.
Treatable Conditions That May Cause Dementia:
The dementia in these conditions may be reversible or partially reversible, even if the underlying disease or damage is not.
- Normal Pressure Hydrocephalus (NPH): The brain is bathed in a clear fluid called cerebrospinal fluid. This fluid also fills internal spaces in the brain called ventricles. If too much fluid collects outside the brain, it causes hydrocephalus. This condition raises the fluid pressure inside the skull and compresses brain tissue from outside and often results in severe damage or even death. If fluid builds up in the ventricles, the fluid pressure bathing the brain remains normal, but brain tissue is compressed from within, thus causing NPH. In normal pressure hydrocephalus, people have trouble walking and become incontinent (unable to control urination). At the same time, they start to lose mental functions, such as memory. If normal pressure hydrocephalus is diagnosed early enough, the internal fluid pressure may be lowered by putting in a shunt. This can stop the dementia, the gait problems, and the incontinence from getting worse.
- Nutritional deficiencies: Deficiencies of certain nutrients, especially B vitamins and Folic Acid, can cause dementia if not treated in a timely fashion. Decreased dietary intact of certain foods or loss of appetite leading to poor eating habits are the major causes of nutritional deficiencies in the elderly.
- Brain tumors: Tumors can cause dementia symptoms in a number of ways. A tumor can press on structures in the brain that control hormone secretion. They can also press directly on brain cells, damaging them. Treating the tumor, either medically or surgically, can reverse the symptoms in some cases.
- Head injury: This refers to brain damage from accidents or injuries, such as motor vehicle accidents or falls; from assaults, such as gunshot wounds or beatings; or from activities such as boxing without protective gear. The resulting damage of brain cells can lead to dementia.
- Infections: Infections of the brain that occurs with meningitis and encephalitis, are often primary causes of dementia. Other infections, such as HIV/AIDS and syphilis, can affect the brain in later stages. In all cases, inflammation in the brain damages cells.
In summary, the cause of dementia can be complex and often times confusing. Early intervention is required, especially to determine if the cause is reversible or irreversible. Should it be due to an irreversible cause, early detection of the form of dementia that is present, along with the use of medication for that type of dementia is required to slow the progression of the disease.
Authored by Dr.Pam Hiti