Understanding Alzheimer's Disease: the Basics

Medically Reviewed by Poonam Sachdev on July 08, 2024
Written by Rachel Reiff Ellis
11 min read

It’s a disease that robs you of your memory. At first, you may have a hard time remembering recent events, though you might easily recall things that happened years ago.

As time goes on, other symptoms can appear, including:

  • Trouble focusing
  • A hard time doing ordinary activities
  • Feeling confused or frustrated, especially at night
  • Dramatic mood swings – outbursts of anger, anxiety, and depression
  • Feeling disoriented and getting lost easily
  • Physical problems, such as an odd walk or poor coordination
  • Trouble communicating

People with Alzheimer's might forget loved ones. You might forget how to dress yourself, feed yourself, and use the toilet.

The disease makes your brain tissue break down over time. It usually happens to people over age 65.

People can live with Alzheimer's disease for just a few years or for a few decades. But more often, people live with it for about 9 years. About 1 in 8 people ages 65 and over have the disease. Women are more likely to have it than men.

Alzheimer’s vs. dementia

Alzheimer’s and dementia are related, but the terms mean different things. 

Dementia isn’t a specific disease. It’s a general term that describes conditions with symptoms that include problems with memory, thinking skills, and behavior. 

Alzheimer’s is the most common type of dementia. It’s a specific disease that causes dementia. There are other types of dementia that aren’t Alzheimer’s disease.

Alzheimer’s progresses through three stages:

Early-stage Alzheimer’s (mild)

It can be hard to notice symptoms consistently when someone is in early-stage Alzheimer’s. Only the people closest to the person with the disease may be able to tell a difference in behavior. 

You’ll likely still be able to drive and take part in social activities at this stage, but you may have trouble remembering details, doing certain tasks, planning or organizing, and you may lose things.

Middle-stage Alzheimer’s (moderate)

This is usually the longest stage of Alzheimer’s. It can last for years. Someone in this stage will progress slowly toward more severe symptoms over time. Symptoms will become easier to notice, and they’ll get in the way of everyday living. 

You may start to notice more behavioral changes in this stage, as daily life becomes more difficult to navigate and confusion happens more often. You may need a dedicated caregiver or a group setting for living to stay safe and thrive. 

Late-stage Alzheimer’s (severe)

This stage of Alzheimer’s can often require round-the-clock care. People in late-stage Alzheimer’s may not be aware of their surroundings or be able to do basic physical movements such as walking, sitting, or even swallowing. 

Communication is difficult at this stage. Hospice care can be a great help for families with a loved one with severe Alzheimer’s. 

People who get Alzheimer's disease are usually older, but the disease isn’t a normal part of aging. Scientists aren’t sure why some people get it and others don’t. But they do know that the symptoms it causes seem to come from two main types of nerve damage:

  • Nerve cells get tangles, called neurofibrillary tangles.
  • Protein deposits called beta-amyloid plaques build up in the brain.

Researchers aren’t sure what causes this damage or how it happens, but it could be a protein in blood called ApoE (for apolipoprotein E), which the body uses to move cholesterol in the blood.

There are a few types of ApoE that may be linked to a higher risk of Alzheimer's. It could be that certain forms of it cause brain damage. Some scientists think it plays a role in building the plaques in the brains of people with Alzheimer’s.

Is Alzheimer’s genetic?

The answer to this question is complicated. Researchers have identified several mutations in genes that are linked to Alzheimer’s and may increase or decrease a person’s risk of getting the disease. But Alzheimer’s doesn’t have a single genetic cause. 

People who get Alzheimer’s don’t always have a history of the disease in their families. But having a sibling or parent with it does raise your risk. 

Whether or not ApoE partly causes Alzheimer's, genes almost certainly play a role in the disease. Someone with a parent who had the disease is more likely to have it, too.

To diagnose you with Alzheimer’s, your doctor will start by finding out more about how you’ve been functioning. Your primary care doctor may refer you to a neurologist. They’ll ask you questions that will help them get a better picture of your brain health. Having a loved one there with you is important so that your doctor can learn as much as possible.

They’ll want to know if:

  • You’re having problems with memory or thinking skills, and if so, to what degree.
  • Your behavior or personality has changed.
  • Your cognitive problems are affecting your daily life.

Alzheimer’s tests

Your doctor may also give you specific tests to help make a diagnosis. These include:

  • Neurological tests that assess your memory, problem-solving, attention, counting, and language
  • Blood, urine, and other standard medical tests to help rule out other causes
  • Psychiatric evaluation to examine your mental health
  • Spinal tap to draw cerebrospinal fluid (CSF) 
  • Brain scans with computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET)

The symptoms of Alzheimer’s progress and can look different as you move into later stages. In general, Alzheimer’s causes:

  • Trouble with memory (remembering names, events, places)
  • Problems with thinking and reasoning 
  • Lapses in judgment and decision-making
  • Problems performing tasks such as cooking
  • Tripping and falling more often (problems with depth perception)
  • Changes in personality
  • Wandering 
  • Delusions
  • Withdrawal

Early signs of Alzheimer’s

It’s normal to forget some things as you age, but people with Alzheimer’s may see these signs come on and then stick around:

  • Asking to repeat questions
  • Forgetting conversations
  • Trouble thinking of a word you need in a conversation

The most common things that raise your risk of getting Alzheimer’s include:

  • Age. This is the number one risk factor for Alzheimer’s. Most people who have the disease are 65 or older. After age 65, your chances of getting the disease double every 5 years. Nearly one-third of all people at age 85 have Alzheimer’s.
  • Family history. While it’s not a guarantee that you’ll get the disease if someone in your family has it, you’re more likely to get it yourself.
  • Genetics. Having certain genes can raise your risk of getting Alzheimer’s. One gene that researchers have identified as having a link to Alzheimer’s is apolipoprotein E (ApoE). But having the gene isn’t a cause by itself; it simply increases your chances of getting the disease.

There is some evidence that people with high blood pressure and high cholesterol have a greater chance of getting Alzheimer's. More rarely, head injuries may be a reason, too – the more severe they are, the greater the risk of Alzheimer's later in life.

Scientists are still studying many of these theories, but it’s clear that the biggest risks linked to Alzheimer's disease are being older and having Alzheimer's in your family.

Research shows that older adults of Hispanic descent are about one-and-a-half times more likely to have Alzheimer’s and dementia as White older adults. Black older adults are about twice as likely to have the disease as their White counterparts.

Although Alzheimer’s doesn’t yet have a cure, there are medications you can take to help slow the progression and help you manage your symptoms.

The medications your doctor suggests will depend on your stage of Alzheimer’s and the symptoms that you’re having. 

Some medications are FDA-approved to treat Alzheimer’s disease itself: 

Lecanemab (Leqembi). This medication is a disease-modifying immunotherapy, which means it works to slow down the progression of the actual disease and not just symptoms. Lecanemab treats mild cognitive impairment or mild Alzheimer’s by removing abnormal beta-amyloid to help reduce the number of plaques in the brain. 

Donanemab (Kinsula). This is the most recent disease-modifying drug the FDA has approved for Alzheimer’s. You get this monoclonal antibody as an IV infusion once every 4 weeks.

Other medications work to manage symptoms of Alzheimer’s:

Brexpiprazole is a type of atypical antipsychotic that can help treat agitation caused by Alzheimer’s. 

Cholinesterase inhibitors are medications that prevent acetylcholine (a chemical messenger) from breaking down in your brain so nerves work better. 

Memantine is a type of medication called an NMDA antagonist. It treats symptoms of moderate to severe Alzheimer’s by blocking the toxic effects that can come from too much glutamate.

Memantine and donepezil combination. This NMDA antagonist and cholinesterase combination uses both medications’ actions (blocking the toxic effects of excess glutamate and preventing the breakdown of acetylcholine) to help slow down cognitive decline.

When you live with Alzheimer’s, both the physical and behavioral effects of the disease can lead to other issues, such as:

  • Falling. It’s harder to get a good read on where your body is in space when you have the disease, so falls are more common. Falls can also lead to more injuries, such as fractures.
  • Worsening health. When Alzheimer’s starts getting in the way of clear communication, it can be hard for people with the disease to tell others when they’re in pain or explain other health issues that are happening. Taking medication and caring for yourself become more difficult, too.

In the later stages, more severe symptoms can cause other complications, such as:

  • Inhaling food or liquid into the lungs
  • Flu, pneumonia, and other infections
  • Bedsores
  • Poor nutrition or dehydration
  • Constipation or diarrhea
  • Dental problems such as mouth sores or tooth decay 

Although the outlook for Alzheimer’s is generally poor, the disease affects everyone differently. It’s impossible to predict exactly how the disease will progress for your loved one. But you can learn more about what the typical outlook is for the different stages. 

On average, people with Alzheimer’s die 4 to 8 years after diagnosis. But some people live as long as 20 years after they first see symptoms. 

There isn’t a proven way to prevent getting Alzheimer’s. But certain lifestyle choices can reduce your risk.

 Reduce high blood pressure. Doctors consider high blood pressure in midlife a risk factor for cognitive decline later on. 

  • Get regular exercise. Physical activity improves your quality of life and helps reduce problems that can lead to cognitive decline, such as depression, diabetes, falls, and heart problems.
  • Care for your hearing. Prevent and treat hearing loss, which can add to a decline in thinking skills as you age.
  • Eat a healthy diet. Studies show that limiting sugar and saturated fats while getting plenty of fruits, vegetables, and whole grains can help protect the brain.
  • Stay social. Using mental energy to connect with others may lower your risk of cognitive decline.
  • Protect your head. There’s evidence that head trauma leads to future problems with mental skills. Fall-proof your home, strengthen your core and balance with exercise, wear a helmet when needed, and always wear your seatbelt. 

You can take steps to live well after an Alzheimer’s diagnosis. Focus on the things you can control:

Lower stress. Learn what triggers stress in your daily life, and try to reduce your exposure. Get plenty of sleep, and make time for things that bring you joy. Practice relaxation techniques such as deep breathing exercises, tai chi, or meditation. 

Get regular checkups. See your doctor so your disease is well-monitored. Find someone you trust and feel comfortable with so they can be a source of support for diet, exercise, mental health, and whole-body wellness.

Keep using your brain. Practice a hobby, take a class, or challenge yourself to try a new activity. Choose things you enjoy, and nourish your mind.

Feel your emotions. You’re likely to run the gamut of feelings, from anger to confusion to acceptance. There’s no right or wrong way to feel, so don’t push your feelings aside. 

Accept what you can’t do. Pretending you’re not struggling can create more stress. Learn to ask for help with the things you can’t do so you can enjoy the things you can. 

Come up with a routine. Knowing what’s to come in your day can be a source of comfort. 

 Find a community. See if there are support groups in your area. Connecting with other people dealing with Alzheimer’s may help you feel less alone. 

At some point, everyone who has Alzheimer’s will need help with daily life. If you are a caretaker for someone with Alzheimer’s, these tips can help you help your loved one’s days go a little more smoothly.

  • Manage medications. Staying organized can be hard for someone with Alzheimer’s. In the early stages, help them come up with systems, such as daily pill trackers. In later stages, be the medication delivery system for them so they get the treatment they need.
  • Routine is key. Keep a similar schedule as best you can every day, helping them bathe, dress, and eat at the same time.
  • Create lists. Help the person write down to-do lists, appointments, and events in a notebook or calendar.
  • Allow them independence when possible. Try not to step in if it’s not necessary.
  • Outfit them with easy wear. Buy loose-fitting, comfortable, easy-to-use clothing, such as clothes with elastic waistbands, fabric fasteners, or large zipper pulls instead of shoelaces, buttons, or buckles.
  • Help their house be fall-proof. Remove area rugs and improve lighting where you can. Install railings and shower handles or a shower chair. 
  • Be gentle, respectful, and clear. Make sure your loved one knows what’s happening. Include them in conversation and be patient. 

Alzheimer’s disease is a disorder that slowly damages the part of your brain responsible for memory. The disease has three stages: early (mild), middle (moderate), and late (severe). Certain things such as age and family history raise your risk of getting it. There are treatments to help manage the symptoms and slow the disease progression, as well as lifestyle changes you can make to help reduce your risk of getting the disease.

What is the end of life like for those who have Alzheimer's?

As you near the last stages of this disease, your symptoms become severe enough that you have trouble talking, communicating, or even swallowing on your own. Palliative and hospice care can help both the person with Alzheimer’s and their family. Through their support, you can learn ways to care for your loved one and know when they’re nearing death. 

Is Alzheimer's hereditary?

Only about 5% of Alzheimer’s cases are inherited from family members. Most cases are sporadic, meaning they don’t come from family. 

What is the difference between Alzheimer and dementia?

Alzheimer’s is a type of dementia – the most common type. Dementia is an umbrella term for conditions with symptoms including problems with memory, thinking skills, and behavior. You can have dementia without having Alzheimer’s, but everyone with Alzheimer’s has a form of dementia.

What stage is aggression in Alzheimer's?

Anger and aggression can happen as the disease gets worse, in the moderate to severe stages.