Using a non-stereological method, the isotrophic fractionator, Azevedo et al. (2009) found the total number of cells in four brains from 50-, 51-, 54-, and 71- year-old males, deceased from non-neurological causes and without cognitive impairment to have on average 86.1 ± 8.1 billion NeuN-positive cells (“neurons”) and 84.6 ± 9.8 billion NeuN-negative (“non-neuronal”) cells. Here, RBFOX3 is linked to Cognitive impairment.