It is one of the most common causes of disability among the elderly but can develop before the age of 65 when it is known as early-onset dementia or presenile dementia. Less than 1% of those with Alzheimers have gene mutations that cause a much earlier development of the disease, around the age of 45, known as early-onset Alzheimers disease. More than 95% of people with Alzheimers disease have the sporadic form (late onset, 80–90 years of age). Worldwide the cost of dementia in 2015 was put at US$818 billion. People with dementia are often physically or chemically restrained to a greater degree than necessary, raising issues of human rights. Social stigma is commonly perceived by those with the condition, and also by their caregivers. History
Until the end of the 19th century, dementia was a much broader clinical concept. It included mental illness and any type of psychosocial incapacity, including reversible conditions. Dementia at this time simply referred to anyone who had lost the ability to reason, and was applied equally to psychosis, "organic" diseases like syphilis that destroy the brain, and to the dementia associated with old age, which was attributed to "hardening of the arteries". Dementia has been referred to in medical texts since antiquity. One of the earliest known allusions to dementia is attributed to the 7th-century BC Greek philosopher Pythagoras, who divided the human lifespan into six distinct phases: 0–6 (infancy), 7–21 (adolescence), 22–49 (young adulthood), 50–62 (middle age), 63–79 (old age), and 80–death (advanced age).
For example, Microsporum audouinii was the predominant etiological agent in North America and Europe until the 1950s, but now Trichophyton tonsurans is more common in the US, and becoming more common in Europe and the United Kingdom. This shift is thought to be due to the widespread use of griseofulvin, which is more effective against M. audounii than T. tonsurans; also, changes in immigration patterns and increases in international travel have likely spread T. tonsurans to new areas. Another fungal species that has increased in prevalence is Trichophyton violaceum, especially in urban populations of the United Kingdom and Europe. See also
List of cutaneous conditions
Ringworm affair

Footnotes
References
Richardson M. (2003). Fungal Infection: Diagnosis and Management. Cambridge, MA: Blackwell Publishers. ISBN 1-4051-1578-5. == External links ==