CP and obsessive-compulsive disorder: Copper is an essential metal ion for numerous metalloproteins, such as ceruloplasmin and cytochrome oxidase.62 The deficiency of copper can lead to various pathologies such as Menkes disease and Wilson disease.63 On the other hand, over-accumulation of copper can reportedly contribute to AD, schizophrenia, and obsessive-compulsive disorder.51,63 For AD pathology, copper has been considered as an important trigger in the harmful crosslinking of Aβs.