1. Alzheimer’s disease is a progressive, degenerative disorder that attacks the brain’s nerve cells (neurons) that produce the brain chemical (neurotransmitter) acetylcholine. The disorder causes the connections between the nerve cells to break and ultimately die. The destruction of these nerve cells results in loss of memory, thinking, and language skills, and can cause behavioral changes.

2. Alzheimer’s is the most common form of dementia, a general term for a range of mental impairments such as memory loss and inability to focus that are both persistent and serious enough to affect a person’s ability to function normally. Dementia is a syndrome (a group of symptoms that doesn’t have a definitive diagnosis) and is not, like Alzheimer’s, a distinct disease. Neither dementia nor Alzheimer’s is part of the natural aging process.

3. Alzheimer’s disease symptoms vary among individuals, but the most common initial symptom is a gradually worsening ability to remember new information. According to the Alzheimer’s Association, this occurs because the first neurons to be damaged and destroyed are usually in brain regions involved in forming new memories. As neurons in other parts of the brain are damaged and destroyed, individuals experience other difficulties. Other common symptoms of Alzheimer’s are memory loss that disrupts daily life, challenges in planning or solving problems, difficulty completing familiar tasks at home, at work or at leisure, and confusion with time or place.

4. Alzheimer’s disease is named after the German clinical psychiatrist and neuroanatomist Alois Alzheimer. In 1906 Alzheimer gave a lecture at a meeting of German psychiatrists in which he identified an “unusual disease of the cerebral cortex” that affected Auguste Deter, a woman in her 50s. The disease caused Deter to suffer disorientation, hallucinations, and memory loss before leading to her death at age 55. At the time the lecture—and the discovery—attracted little notice. Although the local press commented extensively on the lectures given at the meeting, only two lines were devoted to Alzheimer’s lecture.

5. Among the leading causes of death in the United States, Alzheimer’s disease ranks sixth. In 2014, 93,541 Americans died from the disease. However, official mortality figures may be substantially underreporting deaths due to the disease. Recent research shows that the disorder may rank third, just behind heart disease and cancer, as a cause of death for older people. And a 2014 study published in the journal Neurology found that the number of deaths due to Alzheimer’s disease in people 75 and older could be six-times higher than the official count, with researchers’ estimating that 503,400 deaths in 2010 were due to Alzheimer’s.

6. People with Down’s syndrome have an increased risk of developing Alzheimer’s disease in middle age. One study found that the proportion of the overall population with Down’s syndrome and dementia is about 17 percent, and that about one-third (32.1 percent) of people aged 55 to 60 that had Down syndrome also suffered from dementia.

7. People with fewer years of formal education are at higher risk for Alzheimer’s and other dementias than those with more years of formal education. Some epidemiological studies appear to suggest that lifelong experiences, including educational and occupational attainment, and leisure activities in later life, can increase a person’s “cognitive reserve” (i.e., the mind’s resistance to damage and deterioration in the brain) that enables individuals to better compensate for changes in the brain that could result in symptoms of Alzheimer’s or another dementia.

8. To diagnose Alzheimer’s a primary doctor or neurologist (a physician trained in brain conditions) will review a patient’s medical and medication history and consider all related symptoms. According to the Mayo Clinic, the doctor may also order additional laboratory tests, brain-imaging tests, or send the patient for memory testing. Such tests can help doctors rule out other diseases that cause similar symptoms.

9. Currently, there is neither a cure for Alzheimer’s nor a way to reverse the damage caused by the disease. However, new research announced last week might lead to a breakthrough in understanding the disease. Researchers at Northeastern University say that Alzheimer’s disease may “progress not like falling dominoes, with one molecular event sparking the formation of plaques throughout the brain, but rather like a fireworks display, with a unique flare launching each plaque, one by one.” The finding provides “critical insights for developing therapies to slow, halt, or reverse” the disease, the researchers say.