Alzheimer’s disease is a progressive disorder that causes brain cells to waste away (degenerate) and die. Alzheimer’s disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social skills that disrupts a person’s ability to function independently.
As the disease advances, symptoms can include problems with language, disorientation (including easily getting lost), mood swings, loss of motivation, not managing self-care, and behavioral issues. As a person’s condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the typical life expectancy following diagnosis is three to nine years.
The cause of Alzheimer’s disease is poorly understood. About 70% of the risk is believed to be inherited from a person’s parents with many genes usually involved. Other risk factors include a history of head injuries, depression, and hypertension. The disease process is associated with plaques and neurofibrillary tangles in the brain. A probable diagnosis is based on the history of the illness and cognitive testing with medical imaging and blood tests to rule out other possible causes.
Initial symptoms are often mistaken for normal aging. Examination of brain tissue is needed for a definite diagnosis. Mental and physical exercise, and avoiding obesity may decrease the risk of AD; however, evidence to support these recommendations is weak. There are no medications or supplements that have been shown to decrease risk.
Alzheimer’s Disease Symptoms
To receive a diagnosis of Alzheimer’s, the person must have experienced a decline in cognitive or behavioral function and performance compared with how they were previously. This decline must interfere with their ability to function at work or in usual activities.
The cognitive decline must be seen in at least two of the five symptom areas listed below:
1. Reduced ability to take in and remember new information, which can lead, for example, to:
- Repetitive questions or conversations
- Misplacing personal belongings
- Forgetting events or appointments
- Getting lost on a familiar route
2. Impairments to reasoning, complex tasking, and exercising judgment, for example:
- Poor understanding of safety risks
- Inability to manage finances
- Poor decision-making ability
- Inability to plan complex or sequential activities
3. Impaired visuospatial abilities that are not, for example, due to eyesight problems. These could be:
- Inability to recognize faces or common objects or to find objects in direct view
- Inability to use simple tools, for example, to orient clothing to the body
4. Impaired speaking, reading, and writing, for example:
- Difficulty thinking of common words while speaking, hesitations
- Speech, spelling, and writing errors
5. Changes in personality and behavior, for example:
- Out-of-character mood changes, including agitation, apathy, social withdrawal or a lack of interest, motivation, or initiative
- Loss of empathy
- Compulsive, obsessive, or socially unacceptable behavior
If the number and severity of symptoms confirm dementia, the following factors can then confirm Alzheimer’s.
- A gradual onset, over months to years, rather than hours or days
- A marked worsening of the individual’s normal level of cognition in particular areas
If symptoms begin or worsen over the course of hours or days, you should seek immediate medical attention, as this could indicate an acute illness.
Alzheimer’s is most likely when memory loss is a prominent symptom, especially in the area of learning and recalling new information.
Language problems can also be a key early symptom, for example, struggling to find the right words.
If visuospatial deficits are most prominent, these would include:
- Inability to recognize objects and faces
- Difficulty comprehending separate parts of a scene at once
- Difficulty with reading text, known as alexia
The most prominent deficits in executive dysfunction would be to do with reasoning, judgment, and problem-solving.
Other early signs
In 2016, researchers published findings suggesting that a change in sense of humor might be an early sign of Alzheimer’s.
Recent research suggests that the features of Alzheimer’s, such as brain lesions, may already be present in midlife, even though symptoms of the disease do not appear until years later.
Early-onset Alzheimer’s disease
Early-onset familial Alzheimer’s disease can affect younger people with a family history of the disease, typically between the ages of 30 and 60 years.
It accounts for under 5 percent of all Alzheimer’s cases.
Alzheimer’s Disease Stages
The progression of Alzheimer’s can be broken down into three main stages:
- Preclinical, before symptoms appear
- Mild cognitive impairment, when symptoms are mild
In addition, the Alzheimer’s Association describes seven stages along a continuum of cognitive decline, based on symptom severity.
The scale ranges from a state of no impairment, through mild and moderate decline, eventually reaching “very severe decline.”
A diagnosis does not usually become clear until stage four, described as “mild or early-stage Alzheimer’s.”