Changes in the brain
Scientists study the brains of people who have had Alzheimer’s disease.
They can only do this after a person has died. Microscopes are used to see brain changes. These changes include amyloid plaques and tau tangles.
Amyloid plaques
Scientists have noticed that plaque sometimes builds up around neurons, or nerve cells. This plaque is made up of protein pieces called beta-amyloid. Beta-amyloid is sticky and can clump together. This forms plaque. When the beta-amyloid sticks together around neurons, it is called amyloid plaque.
Small groups of beta-amyloid can stop neurons from talking to each other. Beta-amyloid can also affect the immune system. It can cause swelling and getting rid of unhealthy cells. A lot of research exists on how beta-amyloid affects Alzheimer’s disease.
Tau tangles
Tau is another protein that can be found in the brain. Tau can build up in neurons, or nerve cells. Inside a neuron, there are long and tiny tubes called microtubules. They help move things like nutrients inside the cell. Tau helps keep microtubules straight. When they are straight, nutrients have an easy time moving inside the cell.
In Alzheimer’s disease, tau stops helping microtubules stay straight. Tau proteins start to stick to each other. They form twists, called "tangles." When tau forms tangles instead of helping microtubules, the microtubules disappear. This means things like nutrients can't move in the cell. The neurons die from this.
Scientists have studied the brains of patients with Alzheimer’s disease after they have died.
Under a microscope, scientists have found specific changes that occur in the brain during Alzheimer’s disease. These changes involve two things called amyloid plaques and tau tangles.
Amyloid plaques
One change scientists have noticed is the presence of clumps of sticky protein pieces called beta-amyloid. In Alzheimer’s disease, too many of these clumps build up around neurons in the brain, getting in the way of how the brain is supposed to function. These are called amyloid plaques.
Scientists believe that amyloid plaques stop neurons from talking to each other. They may also affect the immune system. This can cause inflammation and can also stop the body from getting rid of unhealthy neurons. There is a lot of research on how amyloid plaques affect Alzheimer's disease.
Tau tangles
Tau proteins are proteins normally found in certain cells of the body, especially neurons. Tau helps keep the support and transport system working in a healthy brain. It guides nutrients and other supplies to the body.
In Alzheimer's disease, tau proteins stick to each other, forming twisted strands called "tangles." These tau tangles disrupt the transport system, so nutrients can't move around as easily. This causes neurons to die.
The brains of patients with Alzheimer's disease have been studied post mortem, and researchers have observed structural changes under a microscope.
Amyloid plaques
The presence of deposits, called plaques, that abnormally accumulate around neurons have been observed in Alzheimer's. These plaques are referred to as amyloid plaques because they are made up of sticky clumps of beta-amyloid protein.
Much research has focused on how beta-amyloid influences Alzheimer’s disease. Amyloid plaques are thought to block the communication signals that flow between neurons. They may also activate the immune system, triggering inflammation and the clearance of unhealthy neurons.
Tau tangles
Another change that has been observed in the brain is an abnormal accumulation of another protein called tau. In healthy brains, tau is a key structural component of a neuron’s internal support and transport system responsible for guiding the movement of nutrients and other essential supplies.
In Alzheimer’s disease, tau proteins aggregate and become disorderly, forming twisted strands called “tangles.” These tangles disrupt the transport system and cause neuron death.
References: 1. https://www.alz.org/alzheimers-dementia/what-is-alzheimers/brain_tour_part_2 2.https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease 3.https://www.health.harvard.edu/topics/alzheimers-and-dementia
