Alzheimer’s Brain: What Happens In A Brain With Alzheimer’s Disease?

Medically reviewed by Melissa Guarnaccia, LCSW
Updated April 15, 2024by BetterHelp Editorial Team

Aging typically brings with it many physical, cognitive, and emotional changes. While some of these changes can be treated and managed with medical care, Alzheimer’s disease is a condition that may not be addressed as easily. It usually involves changes in the brain that can affect memory and cognitive functioning. Neurofibrillary tangles and beta-amyloid plaques are often thought to contribute to the damage to neurons that is usually seen in those with Alzheimer’s disease. While medical care is often crucial for those living with this disease, it can also be vital to seek mental health care in the form of in-person or online therapy. Comprehensive treatment can help those living with Alzheimer’s disease to receive the support they deserve.

Are you or a loved one experiencing memory loss?

Normal brain vs. Alzheimer’s brain

The brain can be considered your body's most influential and critical organ because it generally runs all the other parts of your body, enables you to think, retains your memories, and governs your personality. The average brain weighs approximately three pounds and has a texture similar to a firm jelly substance. It is generally comprised of three main parts:

  • The cerebrum may be the most significant part of the brain. It typically controls cognitive functions, such as problem-solving, remembering, thinking, and feeling, as well as the ability to move.
  • The cerebellum is normally located at the back of the head and controls general coordination and the ability to balance.
  • The brain stem is generally located below and in front of the cerebellum. It normally serves to connect the brain and spinal cord and can be responsible for controlling crucial automatic body functions. These usually include breathing, heart rate, blood pressure, and digestion.

Your brain is normally provided with oxygen from your blood. With each heartbeat, your arteries may carry approximately 20% to 25% of the blood in your body to your brain. Ultimately, your brain can use about 20% of the blood’s oxygen. When you are intently concentrating, your brain may use up to 50% of the oxygen flowing through your body.

All that oxygen may be needed because of the billions of cells in your brain. Those brain cells may constantly work to keep you alive and carry out various cognitive processes. Different parts of the brain are usually dedicated to specific tasks. Examples of these functions can include processing outside stimuli, interpreting sensations, making plans, initiating action, and moving the body.

The hippocampus is a part of the brain that can transfer information into long-term memory, and it can be of particular importance in Alzheimer’s disease. This part of the brain's limbic system usually assists with knowledge and forming memories. Damage to the hippocampus can impair the ability to create new memories.

How does Alzheimer's affect the brain?

No matter what part of the brain is in action, the brain's work is typically done by individual cells. Branches may connect these nerve cells, or neurons. The units of cells can be referred to as axons. Signals can travel along these axons to carry messages from one neuron to another. In a brain with Alzheimer's disease, the neurons can become damaged and eventually destroyed. This can disrupt and impair the way that signals move through the brain.

Researchers think this neuron damage may happen because of two processes. One may be the formation of neurofibrillary tangles. These are usually made up of twisted strands of the protein tau. The tau is generally supposed to be in lines or tracks to transport nutrients. However, it can collapse into tangles, meaning that nutrients can no longer go to the nerve cells, which can cause them to die. 

Second, beta-amyloid plaques, or abnormal cluster protein fragments, can also build up between the brain's nerve cells. Research indicates these plaques can block signaling in the brain's nerve cells.

Scientists are not entirely sure what causes these changes in the brain. However, some changes appear to result from genetic and environmental factors. For example, research shows that a genetic mutation can increase levels of risk. Studies have also found that a head injury sustained earlier in life may also increase the risk of developing Alzheimer’s disease.

What part of the brain does Alzheimer’s affect?

As noted above, the hippocampus is normally the part of the brain responsible for putting information into long-term memory. This part of the brain is usually necessary for this process. If the hippocampus becomes damaged, it can severely affect memory. Generally, after hippocampal damage, people are unable to form new memories. This can result in individuals “living in the past” if they still can remember their old memories. Conversely, this can result in individuals living only in the present moment, as they may immediately forget information.

Alzheimer’s disease tends to be the single most common cause of dementia and, according to the DSM-5, may account for 60% to over 90% of all cases. Alzheimer’s disease usually affects the hippocampus first. This part of the brain tends to be the most severely affected by the condition. The disease may then move through several stages, with symptoms typically worsening over time as the neuron damage spreads throughout the brain's cortex. This may be why memory is often the first cognitive function to be affected, and over time, other functions may also be impacted as the damage increases.

How is Alzheimer's disease diagnosed?

Brain scans and similar procedures may help doctors diagnose Alzheimer’s disease, as can a presentation of relevant symptoms. As neurons send signals to the brain, it can lead to thoughts and behaviors. This neuronal firing can also create memories and play a role in personality. Neurons often fire in patterns for certain activities. These patterns can be seen in brain scans, such as a Positive Emission Tomography Scan (PET Scan). If someone's brain is scanned while doing different activities (such as reading or solving math problems), different activity patterns can be observed.

Alzheimer's brain scan results would likely show different patterns than what might be expected from a healthy brain. This is generally because of the changes in neuron function due to the damage from the plaques and tangles built up in the brain. 

However, Alzheimer’s disease may not usually be diagnosed by a brain scan alone because other conditions could also account for those changes in brain activity. It can be tricky to determine what’s truly going on in the brain while a person is living. Historically, Alzheimer’s disease was generally diagnosed with certainty after a person passed away. 

As a result, sometimes the best course of action can be to perform tests to rule out other potential conditions. When no other diagnosis fits the symptoms, then a diagnosis of Alzheimer’s disease can be used to label the condition. Genetic testing may also show a genetic mutation that could support the diagnosis, although that is not always definitive.

After death, if doctors suspect Alzheimer’s disease, they can examine slices of the brain under a microscope as part of an autopsy. When this is done, they may observe fewer nerve cells and synapses than is typical. They may also see the neurofibrillary tangles and beta-amyloid plaques that can be indicative of the disease.

Are you or a loved one experiencing memory loss?

How to get professional support

If you’ve received an Alzheimer’s diagnosis, are close to someone who has, or are generally concerned about your health, it can be beneficial to speak to both a doctor and a mental health professional for insight. Receiving a proper diagnosis and adequate support can help you feel better prepared to address any changes that might come your way.

Suspecting a diagnosis of Alzheimer’s disease can be upsetting. Once a diagnosis is confirmed, there can be grief, anxiety, and depression about the situation. Someone in this situation may seek therapeutic support to help them adjust and cope. Frequently, those with Alzheimer’s disease eventually rely on family as caregivers. 

Benefits of online therapy

Whether you’re living with Alzheimer’s yourself or are close to someone who is, you may be able to benefit from services like online therapy. This type of platform generally allows you to get the care you deserve at a time and from a place that works for you. Whether it be from the comfort of your own home, the office, or somewhere else that brings you peace, you can have control over the environment in which therapy takes place.

Effectiveness of online therapy

Aside from its convenience, online therapy can be a truly beneficial treatment option. According to a 2023 study, internet-based cognitive behavioral therapy can be effective in treating depression symptoms in those living with chronic conditions, such as Alzheimer’s disease.


A brain affected by Alzheimer’s disease is generally subject to damage over time as the disease begins to impact the cells found within each area of the brain. This process usually begins with the hippocampus, the area responsible for memory, and can spread to other regions over time, affecting movement, cognition, speech, and more. Seeking professional care if you believe you may be experiencing symptoms like these can be critical, as can receiving the support of a mental health professional in person or online.

Explore emotions related to Alzheimer's Disease
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