Alzheimer’s disease is a type of dementia. People often confuse the terms dementia, Alzheimer’s disease, and and mild cognitive impairment.
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 (AD) is the most common type of dementia, accounting for an estimated 60-80 % of cases. AD is an irreversible and progressive brain disease, with the most common early symptoms being memory difficulties and trouble learning new information.
AD 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.
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 noted:
- 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 AD, visit the Alzheimer’s Association.
Changes in the Brain in AD
Although identified more than 100 years ago, research into the symptoms, causes, risk factors, and treatment for AD has only developed in the last 30 years. While we do not know what starts the AD process, we do know that it is damaging and progressive, and like other common chronic diseases, probably develops as a result of multiple factors. Much research speculates that many changes in the brain may begin taking place as early as 20 to 30 years before the onset of symptoms or problems are evident. Researchers believe that the accumulation of the protein beta-amyloid plaques and neurofibrillary tangles (aggregates of the protein tau), contribute to the development of AD. As more and more plaques and tangles form in particular areas of the brain, neuron cells 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 forming memories, thoughts, sensations, emotions, movements, and skills.
Mild Cognitive Impairment (MCI)
An established risk factor for Alzheimer’s disease is Mild Cognitive Impairment (MCI), which is a condition where an individual presents with problems with memory, language, and another essential cognitive ability that are severe enough to be noticeable to others and is detected with cognitive tests, but are not severe enough to interfere with daily life and activities. Some studies indicate that up to 10-20% of older adults aged 65 and older have MCI. An estimated 15% of individuals diagnosed with MCI progress and convert to dementia each year. While it is unclear why some individuals will convert from MCI to dementia while others do not, researchers are looking closely at MCI as a possible transitional state between normal aging and the earliest symptoms of AD. Brain imaging and biomarker studies of MCI individuals, may help researchers to detect early changes in the brain like those seen in AD. This could lead to a better understanding of some of the earliest changes, and early detection and diagnosis.
Early Signs and Symptoms
One of the first symptoms reported for AD are memory problems, particularly with newly learned information. Memory difficulties may appear subtle at first, often leading many individuals to question whether the symptoms may be signs of “getting old”. As AD progresses, a person may ask the same question or say something repeatedly within a short period of time, without remembering the prior conversation. Objects may be misplaced and/or lost, and details about recent events may be forgotten. Early in AD, long-term memory remains relatively intact, but memory loss in those areas will eventually develop as the disease progresses.
Mild Alzheimer’s Disease
As Alzheimer’s disease progresses, memory loss continues and changes in other cognitive abilities appear. Problems can include getting lost, trouble handling money and paying bills, repeating questions, taking longer to complete normal daily tasks, poor judgment, and mood and personality changes. People often are first diagnosed in this stage.
Moderate Alzheimer’s Disease
As the disease progresses, neurofibrillary tangles and amyloid plaque spread throughout the brain, beginning in the neocortex. In the moderate stage, damage occurs in areas of the brain that control language, reasoning, 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. They may have hallucinations, delusions, and paranoia, and may behave impulsively.
There may also be a decline in visuospatial skills, language, abstraction, planning and organization. Visuospatial problems may cause a person to become disoriented or lost in familiar environments. Accidents or becoming lost while driving can occur. Language problems such as word-finding difficulty occurs early but impaired comprehension or decreased speech output may occur in the later stages. Declines in planning and organization often result in missed bill payments and difficulty handling finances.
Severe Alzheimer’s Disease
By the final stage, plaques and tangles have spread throughout the brain, and brain tissue has shrunk significantly. People with severe Alzheimer’s cannot communicate and are completely dependent on others for their care. Near the end, the person may be in bed most or all of the time, as the body shuts down.