Brushstrokes on a canvas could help doctors in the early diagnosis of neurodegenerative diseases, according to a study based on the works of famous sufferers Salvador Dali and Willem De Kooning.

Researchers analyzed 2,092 paintings, including the works of two artists Dali and Norval Morrisseau, who were diagnosed with Parkinson's Disease, as well as artists De Kooning and James Brooks, who suffered from Alzheimer's Disease. The study also included the artwork of famous artists Marc Chagall, Pablo Picasso and Claude Monet, who did not suffer from any such disease, for comparison.

Alex Forsythe from the University of Liverpool, one of the authors of the study, told AFP that "Knowing that you have a problem sooner rather than later is always going to be an important medical breakthrough." The study used a specific type of analysis known as fractal analysis to gauge the relative complexity of the artwork. Fractal analysis is typically used to identify fake paintings by analyzing brushstroke patterns.

Often described as "fingerprints of nature," fractals identified in the study revealed a sharp decrease in artistic complexity starting around the age of 40 -- long before De Kooning and Brooks were diagnosed with Alzheimer's.

De Kooning received an official diagnosis in 1989 -- the year he turned 85 --while Brooks was diagnosed with the disease at the age of 79. In the case of Dali and Morrisseau, researchers identified an increase in the "fractal dimension" of artworks produced by middle-age artists, which started to decline when artists entered their late 50s.

Dali was diagnosed with drug-induced Parkinson's disease after his right hand began shaking severely when he was 76 years of age. Comparatively, Morrisseau's diagnosis came at the age of 65.

The indicator for Chagall, Monet and Picasso showed an increase in complexity into old age. "What I'm hoping is that this research will compel analysts to further examine neurological changes much earlier," Forsythe said.

"With dementia, people are concerned about their memory getting worse. This shows something happening long before that," she added. The study also utilized research from the case of former U.S. President Ronald Reagan whose linguistic decline began in 1980 -- long before he revealed his Alzheimer's diagnosis in 1994 at the age of 83.

The article was published in the American Psychological Association's Journal of Neuropsychology and was co-written with Ronan Reilly from Maynooth University in Ireland and Tamsin Williams from the U.K. National Health Service.