An estimated 5.5 million Americans of all ages have Alzheimer's disease. Of the estimated 5.5 million Americans living with Alzheimer's dementia in 2017, an estimated 5.3 million are age 65 and older and approximately 200,000 individuals are under age 65 and have younger-onset Alzheimer's. One in 10 people age 65 and older (10 percent) has Alzheimer's dementia.
Major dictionaries. The longest word in any of the major English language dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis, a word that refers to a lung disease contracted from the inhalation of very fine silica particles, specifically from a volcano; medically, it is the same as silicosis.
The 28-letter antidisestablishmentarianism is often referred to as the longest, and it is the longest noncoined, nontechnical word in English. Other long words include the name for the tobacco mosaic virus (1185 letters) or the enzyme trypthophan synthetase (1909 or 1913 letters). The actual longest word in the world is 189,819 letters long. It is the chemical name for the largest known protein, called 'titin'. * For a link to this word, see the related question or link.