Alzheimer’s disease (AD) is a type of dementia that affects more than 5 million people in the United States and over 50 million worldwide.

Although it’s commonly known to affect adults 65 years and older, up to 5 percent of those diagnosed have early onset Alzheimer’s disease, sometimes called younger-onset. This generally means that the person diagnosed is in their 40s or 50s.

It can be difficult to obtain a true diagnosis at this age because many symptoms may appear to be a result of typical life events such as stress.

As the disease affects the brain, it can cause a decline in memory, reasoning, and thinking abilities. The decline is typically slow, but this can vary on a case-by-case basis.

AD is the most common form of dementia. Dementia is a general term for the loss of memory functions or other mental abilities that affect your daily life.

You or a loved one may be developing early onset AD if you experience any of the following:

Memory loss

You or a loved one may begin to appear more forgetful than normal. Forgetting important dates or events can occur.

If questions become repetitive and frequent reminders are required, you should see your doctor.

Difficulty planning and problem solving

AD may become more apparent if you or a loved one has difficulty developing and following a plan of action. Working with numbers may also become difficult.

This can often be seen when you or a family member begins to demonstrate problems maintaining monthly bills or a checkbook.

Difficulty completing familiar tasks

Some people may experience a greater problem with concentration. Routine day-to-day tasks requiring critical thought may take longer as the disease progresses.

The ability to drive safely may also be called into question. If you or a loved one gets lost while driving a commonly traveled route, this may be a symptom of AD.

Difficulty determining time or place

Losing track of dates and misunderstanding the passage of time as it occurs are also two common symptoms. Planning for future events can become difficult since they aren’t immediately occurring.

As symptoms progress, people with AD can become increasingly forgetful about where they are, how they got there, or why they’re there.

Vision loss

Vision problems can also occur. This may be as simple as an increased difficulty in reading.

You or a loved one may also begin to have problems judging distance and determining contrast or color when driving.

Difficulty finding the right words

Initiating or joining in on conversations may appear difficult. Conversations may randomly be paused in the middle, as you or a loved one may forget how to finish a sentence.

Because of this, repetitive conversations can occur. You may have difficulty finding the right words for specific items.

Misplacing items often

You or a loved one may begin putting items in unusual places. It may become more difficult to retrace your steps to find any lost items. This may lead you or a loved one to think that others are stealing.

Difficulty making decisions

Financial choices may demonstrate poor judgment. This symptom often causes detrimental financial effects. An example of this is donating large amounts of money to telemarketers.

Physical hygiene also becomes less of a concern. You or a loved one may experience a rapid decline in bathing frequency and a lack of willingness to change clothing on a daily basis.

Withdrawing from work and social events

As symptoms appear, you may notice that you or a loved one becomes increasingly withdrawn from common social events, work projects, or hobbies that were previously important. Avoidance can increase as symptoms worsen.

Experiencing personality and mood changes

Extreme swings in mood and personality may occur. A noticeable change in moods may include:

You may notice that you or your loved one is increasingly irritated when something outside a normal routine takes place.

Although AD isn’t an expected part of advancing age, you’re at increased risk as you get older. More than 32 percent of people over age 85 have Alzheimer’s.

You may also have an increased risk of developing AD if a parent, sibling, or child has the disease. If more than one family member has AD, your risk increases.

The exact cause of early onset AD hasn’t been fully determined. Many researchers believe that this disease develops as the result of multiple factors rather than one specific cause.

Researchers have discovered rare genes that may directly cause or contribute to AD. These genes may be carried from one generation to the next within a family. Carrying this gene can result in adults younger than age 65 developing symptoms much earlier than expected.

Talk to a doctor if you or a loved one is finding it increasingly difficult to perform day-to-day tasks, or if you or a loved one is experiencing increased memory loss. They may refer you to a doctor who specializes in AD.

They’ll conduct a medical exam and a neurological exam to aid in the diagnosis. They may also choose to complete an imaging test of your brain. They can only make a diagnosis after the medical evaluation is completed.

There’s no cure for AD at this time. The symptoms of AD can sometimes be treated with medications meant to help improve memory loss or decrease sleeping difficulties.

Research is still being done on possible alternative treatments.

The symptoms of AD may worsen over time. For many people, a period of 2 to 4 years will pass between the onset of symptoms and receiving an official diagnosis from their doctor. This is considered to be the first stage.

After receiving a diagnosis, you or a loved one may enter the second stage of the disease. This period of mild cognitive impairment can last anywhere from 2 to 10 years.

During the final stage, Alzheimer’s dementia may occur. This is the most severe form of the disease. You or a loved one may experience periods of total memory loss and may need help with tasks such as financial management, self-care, and driving.

If you or a loved one has AD, there are many resources available that can provide you with more information or connect you with face-to-face support services.

The National Institute on Aging offers an extensive literature database and has information about the most current research.

The Alzheimer’s Association also provides valuable information for caregivers about what to expect at each stage of the disease.

Prevalence of AD

Early onset AD affects approximately 220,000 to 640,000 people in the United States.