Alzheimer's disease is a progressive neurological condition that causes symptoms of cognitive impairment, such as memory loss, lack of spatial awareness, poor judgement or reasoning, mood swings and delusions, according to the National Institute on Aging. In severe stages, individuals may completely lose basic functions, such as speech and movement.
Alzheimer's disease causes brain cells to deteriorate, leading to the rapid onset of dementia, according to the Alzheimer's Association. Signs of dementia appear in distinct stages, and on average, Alzheimer's disease leads to death about eight years after the symptoms become visible. In the earliest stages, an individual may have mild memory loss and difficulty retaining new information. As the condition progresses, others may notice behavioral changes, disorientation and the tendency to confuse familiar details. An individual may eventually show signs of paranoia and severe memory loss, gradually leading to a total breakdown of intellectual reasoning, mobility and communication skills.
Relatives or friends of Alzheimer's sufferers often notice symptoms when the individual's ability to perform everyday tasks declines, notes the National Institute on Aging. For example, memory loss may cause the individual to get lost when traveling to familiar places or frequently ask others to repeat information. From a behavioral perspective, individuals may show signs of depression, agitation, anxiety and sleeplessness. As of 2015, scientists don't know the cause of Alzheimer's disease, and although developing treatments may help to slow the symptoms, they don't cure the condition.