but dementia. some people would say this is a normal function of living a very long life. and that this is a pathology. we see in brain scans the back half of the brain in people with alzheimer s disease completely deteriorates. the nfl players, though, they don t have alzheimer s disease as a group. it s frontal lobe that s damaged. larry: what is dementia? dementia is the big category. that s where you lose cognitive function that s abnormal for your age. alzheimer s disease is one of the types. the football dementia that we talked about, that s another one of the types. there s blood vessel dementia, where you have a stroke, aids related dementia. i wrote a book called preventing alz i mers. prevent the risk factors. did you know obesity is a rick factor. the more fat on your body, the worse it is. depression is a risk factor.