Sometimes, you hear the words “dementia” and “Alzheimer’s” used interchangeably, but they aren’t the same thing. Dementia is a condition that can be caused by many different diseases or medical conditions, of which Alzheimer’s disease is one. Learn more about the many other types of dementia after the jump!
What is dementia?
Dementia is the loss of intellectual functions (such as thinking, remembering and reasoning) of sufficient severity to interfere with a person’s daily functioning. It is not a disease in itself, but rather a group of symptoms that may accompany certain diseases or physical conditions. Some of the more well known diseases that cause dementia include Alzheimer’s disease, multi-infarct dementia, Huntington’s disease, Pick’s disease, Creutzfeldt-Jakob disease, and Parkinson’s disease. Other conditions which may cause or mimic dementia, such as depression, brain tumors, nutritional deficiencies, head injuries, hydrocephalus, infections (AIDS, meningitis, syphilis), drug reactions, and thyroid problems. It is imperative that all persons experiencing memory deficits or confusion undergo a thorough diagnostic workup. This requires examination by a physician experienced in the diagnosis of dementing disorders and detailed laboratory testing. The examination should include a re-evaluation of all medications. This process will help the patient obtain treatment for reversible conditions, aid the patient and family in planning future care, and provide important medical information for future generations.
Alzheimer’s disease (AD) is the most common cause of dementia, affecting as many as 5 million Americans and accounting for over 70% of cases of dementia. AD is the sixth leading cause of death in adults, after heart disease, cancer, and stroke. AD is a degenerative disease that attacks the brain, begins gradually, and progresses at a variable rate. AD results in impaired memory, thinking, and behavior and can last from 3 to 20 years from the time of onset of symptoms. Warning signs of AD are memory loss that affects job/home skills, difficulty performing familiar tasks, problems finding the right words, disorientation as to time and place, poor or decreased judgment, difficulty with learning and abstract thinking, placing things in inappropriate places, changes in mood and personality, and marked loss of initiative. These deficiencies worsen as the disease progresses, and in the end stages the person is totally incapable of caring for themselves. Identified risk factors are age, family history, head injury, and Type II diabetes. Most people diagnosed with AD are older than age 65; however, AD can occur in people in their 40s and 50s as is referred to as Early-Onset AD. It is possible to have AD and one of the following causes of dementia.
Multi-infarct (Vascular) dementia
Multi-infarct dementia (MID), or vascular dementia, is a deterioration of mental capacity caused by multiple strokes (infarcts) in the brain. MID is the second most common cause of dementia accounting for 17% of all cases. The events may be described as ministrokes, where small blood vessels in the brain become blocked by blood clots, causing the destruction of brain tissue. The main subtypes are mild cognitive impairment, multi-infarct dementia, vascular dementia due to a strategic single infarct, vascular dementia due to hemorrhagic lesions, small vessel disease (which includes vascular dementia due to lacunar lesions and Binswanger’s disease), and mixed Alzheimer’s and vascular dementia. The onset of MID may seem relatively sudden, as it may take several strokes for symptoms to appear. These strokes may damage areas of the brain responsible for a specific function as well as produce general symptoms of dementia. As a result, MID is sometimes misdiagnosed as Alzheimer’s disease. MID is not reversible or curable, but detection of high blood pressure and other vascular risk factors can lead to a specific treatment that may modify MID’s progression. MID is usually diagnosed through neurological examination and brain scanning techniques, such as computerized tomography (CT) scan or magnetic resonance imaging (MRI). Treatments include antiplatelet drugs and controlling major vascular risk factors (hypertension, hypercholesterolemia, smoking and diabetes mellitus to mention a few).
Parkinson’s disease (PD) is a progressive disorder of the central nervous system that affects over one million Americans. In PD, certain brain cells deteriorate for reasons not yet known. PD is often characterized by tremors, stiffness in limbs and joints, speech difficulties, slowed movement, impaired posture and balance, and difficulty initiating physical movement. Late in the course of the disease, some patients develop dementia and eventually Alzheimer’s disease. Conversely, some Alzheimer’s patients develop symptoms of Parkinson’s. Medications such as Levodopa, which converts to dopamine inside the brain, and deprenyl, which prevents degeneration of dopamine-containing brain cells, are used to improve diminished or reduced motor symptoms in PD patients but do not correct the mental changes that occur. Physical therapy, surgery and healthy eating may be included in the treatment plan.
Huntington’s disease (HD) is an inherited, degenerative brain disease that affects the mind and body. The disease usually begins during mid-life, and is characterized by intellectual decline, and irregular and involuntary movements of the limbs or facial muscles. Other symptoms of HD include personality change, memory disturbance, slurred speech, impaired judgment and psychiatric problems. Huntington’s disease currently affects more than 15,000 Americans. Children born to a person with HD have a 50% chance of inheriting the gene that causes HD. The diagnostic process for Huntington’s disease includes an evaluation of family medical history, recognition of typical movement disorders and CAT brain scanning. A genetic marker linked to Huntington’s disease has been identified on chromosome 4 and researchers are working on locating the gene itself. Although there is no treatment available to stop progression of the disease, the movement disorders and psychiatric symptoms can be controlled by drugs.
Creutzfeldt-Jakob disease (CJD) is a rare, fatal brain disorder that causes rapid, progressive dementia and other neuromuscular disturbances. CJD is caused by a transmissible agent. Research suggests that the agent differs significantly from viruses and other conventional agents. The disease can be inherited, but the majority of cases are not. Early symptoms of CJD include failing memory, changes in behavior, and lack of coordination. As the disease advances, usually very rapidly, mental deterioration becomes pronounced, involuntary movements (especially muscle jerks) appear, and the patient experiences severe difficulty with sight, muscular energy, and coordination. Like Alzheimer’s disease, a definitive diagnosis of CJD can be obtained only through examination of brain tissue at autopsy.
Frontotemporal dementia (Pick’s disease)
Frontotemporal dementia, also known as Pick’s disease, is also a rare brain disorder, characterized by shrinkage of the tissues of the frontal and temporal lobes of the brain and by the presence of abnormal bodies (Pick’s bodies) in the nerve cells of affected areas of the brain. Pick’s disease usually begins between the ages of 40 and 60. The symptoms are similar to Alzheimer’s disease, with loss of language abilities, skilled movement and the ability to recognize objects or people. Initial diagnosis is based on family history (Pick’s disease may be inherited), symptoms, tests, and ruling out other causes of dementia. A definitive diagnosis of Pick’s disease is usually obtained at autopsy.
Lewy body dementia
Lewy body dementia (LBD) is an irreversible form of dementia associated with abnormal protein deposits in the brain called Lewy bodies. Symptoms of LBD are similar to Alzheimer’s symptoms and include memory loss, confusion, and difficulty communicating. Hallucinations and paranoia also may become apparent in the earlier stages of the disease and often last throughout the disease process. Although initial symptoms of LBD may be mild, affected individuals eventually develop severe cognitive impairment. Treatments address the cognitive and movement symptoms and hallucinations, and include a variety of therapies.
Normal pressure hydrocephalus
Normal pressure hydrocephalus is an uncommon disorder which involves an obstruction in the normal flow of cerebrospinal fluid. This blockage causes a buildup of cerebrospinal fluid on the brain. Symptoms of normal pressure hydrocephalus include dementia, urinary incontinence and difficulty in walking. Presently, the most useful diagnostic tools are the neuroimaging techniques (ie., MRI). Normal pressure hydrocephalus may be caused by any of several factors including meningitis, encephalitis and head injuries. In addition to treatment of the underlying cause, the condition may be corrected by a neurosurgical procedure (insertion of a shunt) to divert fluid way from the brain.