What is Alzheimer’s?

Alzheimer’s disease is a type of dementia.  People often confuse the terms dementia, Alzheimer’s disease, and and mild cognitive impairment.

Other Dementias >

A Lesson in Terms

  • Dementia – Decline in intellectual ability impacting memory plus one or more other cognitive abilities severe enough to interfere with everyday functioning.
  • Alzheimer’s Disease – The most common type of dementia.
  • Mild Cognitive Impairment – The “borderland” or transitional stage between normal aging and dementia

Overview of Alzheimer’s Disease

Alzheimer’s disease is the most common type of dementia, accounting for an estimated 55-75% of cases.

AD is an irreversible and progressive brain disease, with the most common early symptoms being memory difficulties and trouble learning new information. Alzheimer’s disease was first identified more than 100 years ago by Dr. Alois Alzheimer, a German neuropsychiatrist, in his patient, Auguste Deter, a woman in her 50s who developed memory, language, visual-spatial, and orientation problems as well as delusional thinking.  Upon Auguste’s death, Dr. Alzheimer autopsied her brain, finding atrophy and the two hallmark neuropathological

signs of AD, amyloid plaques and neurofibrillary tangles.  AD was originally thought to be a rare presenile dementia. Until the 1970s, most cases of senile dementia were attributed to arterioscelerosis.  Today Alzheimer’s disease is recognized as the primary cause of cognitive impairment in the elderly.

Types of Dementia: Alzheimer's disease is the primary cause of dementia in at least 55% of cases and the secondary cause in another 20% or more.

Types of Dementia: Alzheimer’s disease is the primary cause of dementia in at least 55% of cases and the secondary cause in another 20% or more.  Click here to read more about other dementias

An estimated 5.4 million Americans of all ages currently have Alzheimer’s disease (Alzheimer’s Association, 2012). This figure includes 5.2 million people 65 and older and another 200,000 individuals under age 65 who have early-onset AD.  In the 2013 Alzheimer’s Disease Facts & Figures report, the Alzheimer’s Association notes:

  • Another American develops Alzheimer’s every 68 seconds; in 2050, an American will develop the disease every 33 seconds.
  • Today, one in nine people age 65 and older has Alzheimer’s and at least one in three people age 85 and older has the disease.
  • One of three seniors 65 and older dies with Alzheimer’s disease.
  • Deaths from Alzheimer’s disease increased 68% from 2000 to 2010, while deaths from other major diseases, including the number one cause of death (heart disease) decreased.
  • In 2013, the direct costs of caring for those with Alzheimer’s to American society will total $203 billion, including $142 billion in costs to Medicare and Medicaid.  Unless something is done, Alzheimer’s will cost an estimated $1.2 trillion (in today’s dollars) in 2050.

While memory difficulties are the most common early symptom of Alzheimer’s, the disease can start with other symptoms.  Warning signs that indicate the need for an evaluation include:

  • Memory loss significant enough to disrupt daily life and activities
  • Difficulty planning or solving problems
  • Challenges carrying out familiar tasks
  • Confusion or disorientation to time or place
  • Difficulty understanding visual images and spatial relationships
  • New problems with speaking or writing
  • Forgetting and misplacing things, while losing the ability to retrace steps
  • Decreased or poor judgment
  • Withdrawal from activities (social, work, etc.)
  • Changes in mood and personality

For more information about these warning signs of Alzheimer’s disease, visit the Alzheimer’s Association.

Brain Changes in Alzheimer’s Disease

Beta amyloid fragments clump into plaques that suffocate neurons

Beta amyloid fragments clump into plaques that suffocate neurons

Although identified more than 100 years ago, researchers have only actively been studying the symptoms, causes, risk factors, and treatment of Alzheimer’s disease since the mid-1970s.  While we do not know what initiates Alzheimer’s, we do know  the disease is damaging and progressive, and like other common chronic conditions, probably a result of multiple factors. Researchers believe that the accumulation of senile plaques – comprised of the toxic beta-amyloid protein – and neurofibrillary tangles – aggregates of the tau protein – in the brain contribute to the development of Alzheimer’s disease. These neuropathological markers of AD start developing as early as 20 to 30 years before the onset of clinically noticeable symptoms. As more and more plaques and tangles form in particular areas of the brain, neurons begin to lose their ability to function and communicate with one another and die. Neurons are a vital part of the communication within the brain, allowing information and signals to be detected and transferred. In Alzheimer’s disease, abnormal accumulation of plaques and tangles cause neuron cells to die, leading to dramatic shrinkage and cell loss affecting areas of the brain that are responsible for memories, thoughts, sensations, emotions, movements, and skills.

Mild Cognitive Impairment (MCI)

Mild Cognitive Impairment (MCI) is widely considered a transitional state between normal aging and Alzheimer’s or another dementia. In MCI, memory and/or other cognitive difficulties (e.g., language, visual-spatial skills) disrupt everyday life (e.g., missing appointments) and are noticeable to the person affected and/or others (e.g., family, friends, work colleagues), but are not severe enough to interfere with basic living skills.  Click here to learn more about the transition from normal aging to Alzheimer’s disease or another dementia.

Progression of Alzheimer’s Disease

Memory problems are the most frequently reported early symptom of AD and often precipitate the individual and/or family seeking a diagnosis. Initially short-term memory and the ability to learn new information is affected.  Memory difficulties may appear subtle at first, often leading many individuals and families to question whether the symptoms are just signs of “getting old.”  As Alzheimer’s disease progresses, a person may ask the same question or say something repeatedly within a short period of time, having forgotten the prior conversation.  Objects may be misplaced and/or lost, and details about recent events may be forgotten.

Mild Alzheimer’s Disease

As Alzheimer’s disease progresses, memory loss continues and other cognitive abilities are affected.  Problems may include difficulty with finding words and expressing ideas, getting lost, difficulty handling money and paying bills, repeating questions, taking longer to complete normal daily tasks, and poor judgment.  Mood (e.g., apathy and depression) and personality changes are also common. Long-term memory, however, remains relatively intact at this stage. Driving becomes hazardous and should be given up.  People are often still first diagnosed in this stage.

Moderate Alzheimer’s Disease

As the disease progresses, beta-amyloid plaques and neurofibrillary tangles spread throughout the brain, affecting language, reasoning, visual-spatial skills, planning and organization, sensory processing, and conscious thought.  Memory loss and confusion increase, and people begin to have problems recognizing family and friends.  They may be unable to learn new things, carry out tasks that involve multiple steps, such as getting dressed, or cope with new situations.  As a result, affected individuals become increasingly reliant on their caregivers who also struggle to manage the variety of behavioral and psychological symptoms (e.g., agitation, wandering, delusions, and hallucinations) common to this stage.

Severe Alzheimer’s Disease

By the final stage, plaques and tangles have spread throughout the brain, and brain tissue has shrunk significantly. Long-term as well as short-term memory is lost. Often speech is limited to a few words. People become increasingly less responsive to others and the environment, and completely dependent on others for their care. Near the end, affected individuals may be in bed most or all of the time, as the body shuts down.  Pneumonia or another infection may preceded death, however, the actual cause of death remains  Alzheimer’s disease.


 

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