What Is Alzheimer’s Disease?

Alzheimer’s disease was first described by Alois Alzheimer, a German psychiatrist and neuropathologist, in 1906. He studied the case of Auguste D., a 51-year-old woman who experienced confusion and progressive memory loss. Following his examination of her brain, he identified distinctive changes in the cerebral cortex. The disease was subsequently named after him.

Alzheimer’s disease is a progressive neurodegenerative condition that affects memory and other cognitive abilities, including thinking, language and reasoning. As the disease progresses, some people may also experience changes in behaviour and psychological symptoms. Over time, these changes can affect everyday activities and lead to a gradual loss of independence.

What Is Dementia?

Alzheimer’s disease is the most common cause of dementia. Dementia is an umbrella term for a group of conditions that affect cognitive function, including memory, thinking, orientation, comprehension, calculation, learning, language and judgement. These difficulties are significant enough to interfere with everyday life and represent a decline from a person’s previous level of functioning.

Dementia is usually progressive, although its course varies depending on the underlying cause. It may also affect emotional control, social behaviour and motivation. Unlike conditions that primarily affect consciousness, dementia is generally characterised by a decline in cognitive abilities while consciousness remains intact, particularly in the early stages.

What Causes Dementia?

Alzheimer’s disease accounts for an estimated 60–70% of dementia cases worldwide. Other causes include vascular dementia, dementia with Lewy bodies and frontotemporal dementia. Some people may have more than one type of dementia-related brain pathology.