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Alzheimer’s Disease, the Most Common Form of Dementia, is One of Many

By Janie Rosman

 

My neighbor was taking one of his thrice-daily strolls with his caregiver, Celia, the other day when he stopped in front of a tissue discarded on the hallway floor. Moving to pick it up, he was stopped by Celia. “He likes to pick things up off the floor whether they belong to him or not,” she told me.

I smiled empathetically as she gently put his hand back on the walker’s handle. “He wants his own way all the time; and if he doesn’t get it, he gets angry,” she said.

“Although several years younger, my dad is the same,” I told her. “He wants to be in charge.”

“He’s been living with  Alzheimer’s disease,” one doctor told us. He was right, it turns out; AD is the most common — yet not the only — form of dementia in people 65 and older, according to Alzheimer’s Weekly, and accounts for between 50 and 70 percent of all dementias.

Dementia is defined as “a collection of symptoms that are caused by disorders affecting the brain and is not one specific disease” by Alzheimer’s Australia, the peak group that provides support and advocacy for the 257,000 Australians living with it.

While the cause of most dementia is unknown, its final stage involves loss of memory, reasoning, speech, and other cognitive functions, and risks of developing dementia increase with age, according to the National Institute on Aging.

Caused by a variety of illnesses, dementia can occur as the result of a stroke (vascular dementia), Parkinson's disease, a brain tumor, a thyroid or other metabolic or endocrine disorder, or any number of reasons; proper diagnosis is necessary to ensure correct treatment.

Data from the 2007 nationally-representative Health and Retirement study concluded that one in seven Americans over age 70 has some form of dementia.

Dementia classifications group disorders that have similar features, such as whether they are progressive or what parts of the brain are affected. The National Institute of Neurological Disorders and Stroke lists some frequently-used classifications:

Cortical dementia — brain damage primarily affects the brain's cortex, or outer layer; tends to cause memory, language, thinking, and social behavior problems.

Subcortical dementia — affects parts of the brain below the cortex; tends to cause emotional and movement changes and memory problems.

Progressive dementia — gets worse as time passes and gradually interferes with more and more cognitive abilities.

Primary dementia — doesn’t result from another disease.

Secondary dementia — occurs as the result of a physical disease or injury.

AD is both a progressive and a cortical dementia. One common type of progressive dementia is Lewy body dementia (LBD), which can occur sporadically in people who have no known family history of this, although rare familial cases are occasionally reported.

Symptoms of LBD overlap with AD in many ways and can include memory impairment, poor judgment, and confusion. People living with LBD can have visual hallucinations, a shuffling gait and flexed posture — symptoms of Parkinson’s disease — and severity of symptoms can vary daily.

Other types of dementia include:

AIDS-related dementia — Also called AIDS dementia complex (ADC); can develop in persons with human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS). While uncommon in people who have early-stage HIV, it can increase as HIV progresses, although not everyone with HIV/AIDS develops ADC. Possible early-stage symptoms include difficulty concentrating and remembering phone numbers or appointments, slower thinking and more time needed to finish complicated tasks, irritability, unsteady walking, poor coordination, and depression.

Creutzfeldt-Jakob Disease — This is most common human form of a rare, fatal brain disorder that affects people and certain mammals. When variant CJD (“mad cow disease”) occurs in cattle, it can be transmitted to people under certain circumstances.

Frontotemporal dementia — Includes other dementias like primary progressive aphasia, Pick's disease and progressive supranuclear palsy. Symptoms include personality and behavioral changes and language difficulties.

Huntington’s disease — This is a progressive brain disorder caused by a single defective gene on chromosome 4, characterized by abnormal involuntary movements, a severe decline in thinking and reasoning skills, irritability, depression and other mood changes.

Mixed dementia — More than one type of dementia occurs at the same time in the brain, most commonly AD and vascular dementia, and can include DLB.

Normal pressure hydrocephalus — Symptoms include walking difficulties, memory loss and inability to control urination.

Parkinson’s disease — This can result in progressive dementia as it develops, similar to AD or DLB. Movement problems are a symptom early on.

Vascular dementia — Previously known as multi-infarct or post-stroke dementia, it’s the second-most common cause of dementia after AD. Initial symptoms can include impaired judgment or ability to plan steps to complete a task, rather than memory loss often associated with the initial symptoms of AD.

Wernicke-Korsakoff Syndrome — This chronic memory disorder is caused by severe deficiency of thiamine (vitamin B-1) and the effect of alcohol on absorption and use of thiamine. Its most common cause is alcohol misuse. Symptoms generally include impaired learning ability, personality changes, problems with memory and balance, and difficulty with clear thinking and planning tasks.

 

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