Distribution of PLP and MAG concentrations by FAQ Status among older brain donors. The x-axis for both is the FAQ dichotomized into impaired (score of 9 or higher) and unimpaired (score <9). The bar is the mean and the error bars are 95% CI. The sample is restricted brain donors who were 50 years or older at the time of death. The figure shows unadjusted associations. Analysis of covariance controlling for age, education level, arteriolosclerosis and CTE stage show differences to be statistically significant: (A) F = 4.48, mean diff. = 33.71, P = 0.036 and (B) F = 4.43, mean diff. = 66.58, P = 0.037.