In vitro studies also support TTR synthesis in neurons as neuroprotective in Alzheimer ́s disease, since primary cultures of mixed cortical and hippocampal neurons from APP23 mice express TTR [17,18], and there is an upregulation of ttr in the SH-SY5Y neuroblastoma cell line over-expressing APP695 isoform [16]. This evidence concerns the gene TTR and early-onset autosomal dominant Alzheimer disease.