The brain is the most complex organ of the human body. It controls functions that affect all aspects of our daily lives – activities like speaking, moving, making decisions, and having emotional responses. The brain also controls functions we're not conscious of – such as digestion, breathing, and circulation.

When a person is suffering from Alzheimer's disease, abnormal changes are taking place in the brain. The cause of Alzheimer's disease begins with nerve cells, responsible for learning and memory functions, which begin to become damaged and eventually die. As a result, certain aspects of brain functioning that control memory, behavior, personality, and other bodily functions, can be lost.¹⁸

As these changes occur, a person with Alzheimer's disease will advance through the stages of Alzheimer's disease, suffering from the various symptoms associated with them.⁹ It's important to understand the stages and symptoms of Alzheimer's disease to ensure appropriate treatment.