How Alzheimer's Disease Changes the Brain

By Amanda Page

Brain Drain

One of the more insidious aspects of Alzheimer's is that it affects different regions of the brain at different times. So, brain functions deteriorate over time until a person is able to do, say, or think very little.
Loading the player ...

First, Some Facts and Figures

Alzheimer's disease is not a normal part of aging. It is the most common form of dementia, a general term for memory loss and cognitive decline serious enough to interfere with daily life. It's also, according to the Centers for Disease Control, the 6th top cause of death in the United States. One in three seniors dies with Alzheimer's or another form of dementia.

"An estimated 5.3 million Americans have Alzheimer's disease."

The Hippocampus

In detailing the deterioration of a brain with Alzheimer's, it makes sense to start with the hippocampus. It's the part of the brain associated with creating new memories and being able to navigate through spaces.

How Alzheimer's Affects the Hippocampus

Alzheimer's disease usually first damages the hippocampus, leading to memory loss and disorientation. Hippocampal damage can also cause amnesia and an inability to form new memories, specifically those regarding time and location.

The Hypothalamus

The hypothalamus is the region of the brain responsible for much of the body’s hormone production. These hormones govern many functions including hunger, sleep, temperature regulation, thirst, sex drive, mood, metabolism, and growth.

The Stages of Alzheimer's Disease


Loading the player ...

The Amygdala

The amygdala is an almond-shape section of nervous tissue located on each side of the brain. It's associated with the perception of emotions, such as anger, fear, sadness and pleasure, as well as our ability to control aggression.

"Nearly 80 percent of Alzheimer’s patients experience symptoms related to amygdala deterioration."

Sources: JAMA Neurology

The Cerebellum

This brain region located at the back of the head is linked to the coordination of voluntary movement, gait, posture, speech and motor functions. The cerebellum is also thought to help with control of cognition that requires precise timing and behavior. It's thought that cell loss here could be related to the coordination problems that often occur in the mid-to-late stages of the disease.

The Frontal Lobe

The frontal lobe is located behind the forehead and is associated with our ability to make decisions, control voluntary movements, solve problems, make plans, control impulses and emotions, and also maintain speech and writing skills.

"Frontal lobe dementia is responsible for about 10 to 15 percent of dementia cases."


Parietal Lobe

The parietal lobe is located above the ear and receives and interprets sensations of pain, pressure, temperature, touch, size and shape, and body part awareness. In most people, the left side of the parietal lobe is thought to be dominant, as it processes information allowing us to read, write, and make calculations.

The non-dominant side of the parietal lobe, usually the right side, helps us 'picture' the world around us by processing appearances.

Loading the player ...

The Occipital Lobe

The occipital lobe is the area of the brain located at the back of the head and its primary purpose is to make sense of what our eyes are seeing. This region of the brain is not always affected by Alzheimer's disease, but when it is, the result can be difficulty in recognizing everyday objects, such as clothing, a toilet, or a bathtub.

The Corpus Callosum

The brain is divided into the right and left hemisphere, which are connected by the corpus callosum.

The corpus callosum is the largest concentration of white matter in the brain, and its millions of nerve cells allow different parts of the brain to communicate with each other.

Loading the player ...

The Thalamus

The thalamus is deep inside the brain, just above the brain stem. It is responsible for relaying motor and sensory signals to the cerebral cortex. It's also linked to the regulation of sleep and consciousness. Plus, it plays a role in controlling the motor systems of the brain responsible for voluntary bodily movement and coordination.

The Temporal Lobe

The temporal lobe is located in the lower part of the brain, behind the ear, and is involved in processing the comprehension of sounds and spoken words, as well as emotion. Since it includes the hippocampus, it also is associated with different types of memory.

The Challenge

These are just the primary regions of the brain most affected by Alzheimer’s--other parts can also be damaged. That's why its impact can be so devastating and why finding a cure, or even a way to slow down its progression, remains one of the biggest challenges facing medical researchers today.

But scientists continue to look for answers, and experts feel they're getting closer to finding ways to cure and even prevent Alzheimer's. For updates on the latest research, see the Alzheimer's Association's website.