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A new study of former football players, from high school to the NFL, found evidence of brain disease in most of them.

FOX's Jessica Rosenthal reports:

Researchers studied the brains of 202 former football players who donated their brains to science after they died. Nearly 90 percent of them showed signs of a brain disease called Chronic Traumatic Encephalopathy or CTE.

When it came to the 111 brains of NFL players in the study, all but one of them had CTE. That brain disease has been tied to hits to the head. Researchers say in the most severe cases of which there were 84, 85 percent showed signs of dementia before they died, according to interviews with family members.

Jessica Rosenthal, FOX News.

Follow Jessica Rosenthal on Twitter: @JessicaFOXNews