What is Alzheimer’s disease?

By name, Alzheimer’s disease is one of the most well-known neurodegenerative diseases, but its pathology is not always fully understood. Here we break down what Alzheimer’s disease actually is, how it develops and how it affects brain health. 

Alzheimer’s disease is a brain disorder that slowly destroys memory and thinking skills, eventually making it impossible to carry out the simplest of tasks. Most people with the disease first start experiencing symptoms in their mid-60’s, whereas in ‘early-onset Alzheimer’s’, which it must be noted is very rare, can occur anywhere between the ages of 30 to mid-60s. 

The disease itself was named after Dr. Alois Alzheimer. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. Her symptoms included memory loss, language problems and unpredictable behaviour. After she died, he examined her brain and found many abnormal clumps which we now know to be beta-amyloid plaques, and, what is referred to as neurofibrillary tau tangles which are tangled bundles of fibre. These plaques and tangles are still considered to be some of the main features of Alzheimer’s disease. 

The healthy human brain contains tens of billions of neurons which are specialised cells that process and transmit information via electrical and chemical signals. They send messages between different parts of the brain, as well as from the brain to the muscles and organs of the body. Alzheimer’s disease disrupts this communication among neurons resulting in loss of function and cell death, further leading to chronic inflammation. 

This loss of connection between the neurons in the brain initially takes place in the hippocampus which involves memory. It then affects the cerebral cortex which is responsible for our language, reasoning and social behaviour, and in its later stages effects the amygdala which helps to regulate our emotions. 

Alzheimer’s disease is one of the most prevalent neurodegenerative diseases, and with no magic pill currently available, prevention is currently the best cure.

To continue reading the pathology of Alzheimer’s disease, please visit The National Institute on Aging.