The edoplasmic reticular tethering of the mitochondria is interesting! In the abstract from the Hindawi paper, my eye goes to this statement:

Specific triggers for ER stress include, for example, particular intracellular alterations (e.g., calcium or redox imbalances), certain microenvironmental conditions (e.g., hypoglycemia, hypoxia, and acidosis), high-fat and high-sugar diet, a variety of natural compounds (e.g., thapsigargin, tunicamycin, and geldanamycin), and several prescription drugs (e.g., bortezomib/Velcade, celecoxib/Celebrex, and nelfinavir/Viracept).

Multiple ER stress triggers could easily be present in a person, especially if specific triggers are common conditions. Presumably more triggers are possible than the examples which were listed, and perhaps more prescription drugs can serve as triggers than the examples listed. As I understand it, many people have experienced a worsening in their Parkinson's symptoms during or after an illness or stressful time. During illness or stress, healthy diet can easily fall by the wayside, and prescription drugs are more likely to be deployed.