No, but perhaps people should recognize that modern medicine doesn't always know what the fuck it's doing. Before the introduction of antipsychotics the recovery rate of schizophrenia in developing nations actually was higher than after. It took the field years to admit that antipsychotics actually slowed recovery because it made the brain dependent on the drug. Then there are psychiatrists claiming schizophrenia stays with you all your life and can't ever be cured. This is absolute horseshit. There are plenty of schizophrenics that show spontaneous recovery, in fact recovered schizophrenics tend to be more succesful in life that the average person, probably because a creative brain resembles a psychotic brain. As for the same drugs being used, that doesn't say shit, many disorders use the same drugs, like antidepressants being subscribed for a shit ton of other stuff other than depression. The same is even true for many neurodegenerative diseases.

The point is Alzheimers and Parkinson probably have more in common than a person with paranoid schizophrenia and another hebephrenic schizophrenia. People like to pretend it's all one big disease with varying subclasses when it probably is more like many unrelated diseases grouped under one name. As for the common factors thing, most mental disorders share the same common environmental factors, that also doesn't say shit.