Late onset Alzheimer’s disease is a common form of dementia that starts after the age of 65. It can cause memory and cognition issues, impaired judgment, and other symptoms as it progresses.

According to a 2019 review, late onset Alzheimer’s disease is the most common form of late onset dementia, which describes a group of symptoms that include difficulties with memory, language, problem-solving, and other thinking skills.

The Alzheimer’s Association estimates that Alzheimer’s disease accounts for 60-80% of dementia cases. According to the National Institute on Aging, late onset Alzheimer’s disease is the most common type of Alzheimer’s disease.

Late onset Alzheimer’s disease differs from early onset Alzheimer’s disease, which can start any time before the age of 65 and may start – in rare cases – as early as 30. However, scientists are still learning about Alzheimer’s disease, and some argue that the early and late onset forms may not reflect distinct underlying causes.

This article reviews the symptoms, causes, diagnosis, treatment, and prevention of late onset Alzheimer’s disease.

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Symptoms of Alzheimer’s disease, including late onset Alzheimer’s disease, typically start out mild and progressively get worse over time. Doctors and other experts break the disease down into four stages, including:

  • preclinical
  • mild (early stage)
  • moderate
  • severe (late stage)

Some experts add an additional stage between preclinical and mild symptoms called mild cognitive impairment due to Alzheimer’s disease. They classify symptoms starting in this phase that do not affect a person’s daily life.

Learn more about the stages of Alzheimer’s disease here.

Preclinical symptoms

There are no obvious symptoms at this stage.

During the preclinical stage, a doctor may be able to see early signs of changes to the brain, such as the formation of amyloid plaques or tau tangles, in imaging scans. This may start 10 years or more before the first symptoms appear.

However, not every person with these brain changes develops dementia.

Learn more about the differences between a brain with Alzheimer’s and a brain without Alzheimer’s here.

Mild or early stage symptoms

During the early stages, a person may feel healthy. However, they may start to experience difficulty with thinking skills, such as memory.

Family members, friends, or the person themselves may start to notice signs and symptoms of Alzheimer’s disease. Healthcare professionals diagnose many cases of Alzheimer’s disease at this stage.

Early symptoms may include:

  • poor judgment, leading to bad decisions
  • memory loss that disrupts daily life
  • taking longer to complete typical daily tasks
  • loss of spontaneity and sense of initiative
  • challenges in planning or solving problems
  • changes in mood or personality
  • losing track of dates or knowing the current location
  • difficulty paying bills or handling money
  • repeating questions or forgetting recently learned information
  • wandering or getting lost
  • misplacing things in odd places or losing them
  • increased anxiety or aggression
  • trouble completing tasks such as bathing

Moderate symptoms

When a person progresses to this stage, they often require additional support. Family members and others may find it more difficult to care for the person.

Symptoms may include:

  • shortened attention span
  • increased confusion and memory loss, such as forgetting events or personal history
  • inability to learn new things
  • withdrawal from social activities
  • difficulty organizing thoughts and thinking logically
  • trouble coping with new situations
  • difficulty with language and problems with reading, writing, and working with numbers
  • inappropriate emotional outbursts
  • hallucinations, paranoia, or delusions
  • repetitive statements or movements, such as muscle twitches
  • changes in sleeping patterns
  • trouble carrying out familiar, multistep tasks, such as getting dressed
  • impulsive behavior
  • occasional problems recognizing family and friends
  • restlessness, agitation, anxiety, tearfulness, wandering, often occurring in the late afternoon or evening

Severe or late stage symptoms

In the late stages of Alzheimer’s disease, a person becomes completely dependent on others for care and cannot communicate effectively. They are typically nearing the end of life and may not be able to get out of bed.

Some symptoms may include:

  • seizures
  • weight loss with little interest in eating
  • inability to communicate
  • no awareness of recent experiences or surroundings
  • groaning, grunting, or moaning
  • increased amount of sleeping
  • general physical decline, including dental, skin, and foot problems
  • loss of bowel and bladder control
  • trouble swallowing

Learn more about end stage dementia here.

Evidence notes that certain factors, such as proteins accumulating in the brain, can contribute towards the development of Alzheimer’s disease. Other probable causes include:

  • age related changes to the brain
  • genetics
  • environmental, lifestyle, and health factors

These factors likely all interact with each other to eventually cause Alzheimer’s disease. How a person responds to changes in any of the risk factors may vary greatly between people.

Experts note that the number of people with Alzheimer’s disease doubles every 5 years following the age of 65, with roughly one-third of people over the age of 85 living with the condition.

Having a close family member with Alzheimer’s disease may increase a person’s risk of developing the condition. However, having a close family member with the disease does not mean a person will definitely develop it.

One key difference between early and late onset Alzheimer’s disease is that late onset may involve changes to the gene APOE ɛ4. In contrast, early onset typically occurs due to a gene that a parent passes down to their child.

Learn more about Alzheimer’s disease and genetics here.

Some other factors that scientists are looking into that may affect Alzheimer’s disease development include:

A doctor typically uses several methods to diagnose Alzheimer’s disease, including late onset Alzheimer’s disease. Some methods include:

  • conducting a physical examination and review of personal and family medical history as well as symptoms, a close family member or friend may also help answer questions about a person’s symptoms
  • providing memory, language, problem solving, and attention tests
  • performing blood and urine tests to rule out other conditions
  • conducting psychiatric evaluation to help rule out conditions such as depression or other mental health conditions that may cause similar symptoms
  • performing a cerebrospinal fluid analysis to check for proteins associated with the disease
  • conducting brain scans to help rule out other possible causes

A doctor may want or need to repeat some of the tests. Repeating memory or thinking tests may help show a decline in function if it exists. A person may need to repeat some tests every 6-12 months.

Treatments cannot cure Alzheimer’s disease, including late onset Alzheimer’s disease. Instead, they focus on helping to slow the progression of the disease and improve overall quality of life.

For mild Alzheimer’s disease, a doctor may prescribe medications known as cholinesterase inhibitors. These medications help to prevent the breakdown of acetylcholine, a brain chemical that may play a role in memory and thinking. Examples include galantamine, rivastigmine, and donepezil.

A doctor may also prescribe immunotherapy for mild Alzheimer’s disease. Immunotherapy medications target a protein called beta-amyloid to help reduce amyloid plaques, which are brain changes associated with Alzheimer’s disease. Examples of immunotherapy medications include lecanemab and aducanumab.

For moderate to advanced Alzheimer’s disease, a doctor may prescribe an N-methyl-D-aspartate antagonist known as memantine. This medication helps to reduce the severity of symptoms and may help a person maintain some cognitive function for longer.

Research for new and better treatments for Alzheimer’s disease is ongoing. A person may be able to participate in clinical trials to both help with research and to get access to new, potentially effective medications.

People should speak with their doctor about which treatments may work best for them, including the possibility of participating in a clinical trial.

Learn more about medications and other treatments for dementia here.

A person may not be able to prevent late onset Alzheimer’s disease due to the complex nature of how different factors influence the condition. However, the Centers for Disease Control and Prevention recommends a person take the following steps to help reduce their risk of developing the condition:

Late onset Alzheimer’s disease occurs after the age of 65. It is the most common form of Alzheimer’s disease.

The disease develops slowly over four stages, although some experts describe five stages. Over the stages, a person’s thinking skills, such as memory and problem-solving abilities, gradually worsen.

Treatments for late onset Alzheimer’s disease may help slow the progression of symptoms and help ease them. People should speak with a healthcare professional about the most suitable treatment options for them.