XBP1 and Parkinson disease: Meth has been shown to induce ER stress through the overexpression of ER stress-related genes, including CHOP and spliced XBP1 [169] and, by augmenting DA levels, triggers ER stress and oxidative stress signalling pathways even in a fetal brain exposed to meth, thus impacting learning and cognitive abilities with significant neurobehavioral deficits [170] similar to some of the PD pathological manifestations.