Alzheimer's stages: How the disease progresses

Alzheimer's disease tends to develop slowly and gradually worsens over several years. Eventually, Alzheimer's disease affects most areas of your brain. Memory, thinking, judgment, language, problem-solving, personality and movement can all be affected by the disease.

There are five stages associated with Alzheimer's disease: preclinical Alzheimer's disease, mild cognitive impairment due to Alzheimer's disease, mild dementia due to Alzheimer's disease, moderate dementia due to Alzheimer's disease and severe dementia due to Alzheimer's disease. Dementia is a term used to describe a group of symptoms that affect intellectual and social abilities severely enough to interfere with daily function.

The five Alzheimer's stages can help you understand what might happen, but it's important to know that these stages are only rough generalizations. The disease is a continuous process. Each person has a different experience with Alzheimer's and its symptoms.

Preclinical Alzheimer's disease

Alzheimer's disease begins long before any symptoms become apparent. This stage is called preclinical Alzheimer's disease, and it's usually identified only in research settings. You won't notice symptoms during this stage, nor will those around you.

This stage of Alzheimer's can last for years, possibly even decades. Although you won't notice any changes, new imaging technologies can now identify deposits of a protein called amyloid-beta that is a hallmark of Alzheimer's disease. The ability to identify these early deposits may be especially important for clinical trials and in the future as new treatments are developed for Alzheimer's disease.

Additional biomarkers — measures that can indicate an increased risk of disease — have been identified for Alzheimer's disease. These biomarkers can be used to support the diagnosis of Alzheimer's disease, typically after symptoms appear.

Genetic tests also can tell you if you have a higher risk of Alzheimer's disease, particularly early-onset Alzheimer's disease. These tests aren't recommended for everyone, but you and your doctor can discuss whether genetic testing might be beneficial for you.

As with newer imaging techniques, biomarkers and genetic tests will become more important as new treatments for Alzheimer's disease are developed.

Mild cognitive impairment (MCI) due to Alzheimer's disease

People with mild cognitive impairment have mild changes in their memory and thinking ability. These changes aren't significant enough to affect work or relationships yet. People with MCI may have memory lapses when it comes to information that is usually easily remembered, such as conversations, recent events or appointments.

People with MCI may also have trouble judging the amount of time needed for a task, or they may have difficulty correctly judging the number or sequence of steps needed to complete a task. The ability to make sound decisions can become harder for people with MCI.

Not everyone with mild cognitive impairment has Alzheimer's disease. MCI is often diagnosed based on the doctor's review of symptoms and professional judgment. But if necessary, the same procedures used to identify preclinical Alzheimer's disease can help determine whether MCI is due to Alzheimer's disease or something else.

Mild dementia due to Alzheimer's disease

Alzheimer's disease is often diagnosed in the mild dementia stage, when it becomes clear to family and doctors that a person is having significant trouble with memory and thinking that impacts daily functioning.

In the mild dementia stage, people may experience:

• Memory loss of recent events. Individuals may have an especially hard time remembering newly learned information and ask the same question over and over.
• Difficulty with problem-solving, complex tasks and sound judgments. Planning a family event or balancing a checkbook may become overwhelming. Many people experience lapses in judgment, such as when making financial decisions.
• Changes in personality. People may become subdued or withdrawn — especially in socially challenging situations — or show uncharacteristic irritability or anger. Reduced motivation to complete tasks also is common.
• Difficulty organizing and expressing thoughts. Finding the right words to describe objects or clearly express ideas becomes increasingly challenging.
• Getting lost or misplacing belongings. Individuals have increasing trouble finding their way around, even in familiar places. It's also common to lose or misplace things, including valuable items.

Moderate dementia due to Alzheimer's disease

During the moderate dementia stage of Alzheimer's disease, people grow more confused and forgetful and begin to need more help with daily activities and self-care.

People with the moderate dementia stage of Alzheimer's disease may:

• Show increasingly poor judgment and deepening confusion. Individuals lose track of where they are, the day of the week or the season. They may confuse family members or close friends with one another or mistake strangers for family.

  They may wander, possibly in search of surroundings that feel more familiar. These difficulties make it unsafe to leave those in the moderate dementia stage on their own.

• Experience even greater memory loss. People may forget details of their personal history, such as their address or phone number, or where they attended school. They repeat favorite stories or make up stories to fill gaps in memory.
• Need help with some daily activities. Assistance may be required with choosing proper clothing for the occasion or the weather and with bathing, grooming, using the bathroom and other self-care. Some individuals occasionally lose control of their bladder or bowel movements.

• Undergo significant changes in personality and behavior. It's not unusual during the moderate dementia stage for people to develop unfounded suspicions — for example, to become convinced that friends, family or professional caregivers are stealing from them or that a spouse is having an affair. Others may see or hear things that aren't really there.

  Individuals often grow restless or agitated, especially late in the day. Some people may have outbursts of aggressive physical behavior.

Severe dementia due to Alzheimer's disease

In the late stage of the disease, called severe dementia due to Alzheimer's disease, mental function continues to decline, and the disease has a growing impact on movement and physical capabilities.

In late stage severe dementia due to Alzheimer's disease, people generally:

• Lose the ability to communicate coherently. An individual can no longer converse or speak in ways that make sense, although he or she may occasionally say words or phrases.
• Require daily assistance with personal care. This includes total assistance with eating, dressing, using the bathroom and all other daily self-care tasks.
• Experience a decline in physical abilities. A person may become unable to walk without assistance, then unable to sit or hold up his or her head without support. Muscles may become rigid and reflexes abnormal. Eventually, a person loses the ability to swallow and to control bladder and bowel functions.

Rate of progression through Alzheimer's disease stages

The rate of progression for Alzheimer's disease varies widely. On average, people with Alzheimer's disease live between three and 11 years after diagnosis, but some survive 20 years or more. The degree of impairment at diagnosis can affect life expectancy. Untreated vascular risk factors such as hypertension are associated with a faster rate of progression of Alzheimer's disease.

Pneumonia is a common cause of death because impaired swallowing allows food or beverages to enter the lungs, where an infection can begin. Other common causes of death include dehydration, malnutrition, falls and other infections.