APOE and Alzheimer disease: In serum, lower Trx80 correlates with higher CSF Aβ42 levels (which in turn is associated with lower amyloid-beta deposition in the brain) [2], and non-ApoE4 carriers showed significantly lower Trx80 levels than ApoE4 carriers, supporting the notion of an inverse relationship between brain and serum Trx80 levels that is further apparent AD individuals carrying ApoE4.