My understanding of the paper is the following: My knowledge of biology is next to null so I will welcome comments and corrections
The cell has an elaborate “sewage” system (autophagy) which rids itself from faulty molecules (faulty enzymes? Which are called mutants such as the famous alpha-synuclein which act as poisons). BUT the ‘famous’ dopamine joins with some of these faulty molecules making a “sticky” kind of compound which renders the sewage system ineffective (like closing the sewers!) . Now with closed sewers, the poisons accumulate in the cell causing its death.
It is amazing that the main culprit is DOPAMINE ! . IT IS OUR SAVER AND OUR KILLER !
Such is the irony of life