Final answer:
Psychoanalysis is least useful in treating schizophrenia, a complex disorder requiring antipsychotic meds and other treatments, not typically addressed through psychoanalysis.
Step-by-step explanation:
Psychoanalysis is considered least useful in treating schizophrenia. Psychoanalysis focuses on exploring the unconscious mind and resolving deep-seated emotional conflicts from one's past. While useful in addressing certain aspects of mental health, such as depression and anxiety disorders, which involve significant emotional and psychological components that can be explored through therapy, schizophrenia is a complex psychological disorder that often requires a combination of antipsychotic medications and possibly other treatments like electroconvulsive therapy or deep-brain stimulation. Schizophrenia involves symptoms like hallucinations, delusions, and cognitive issues, which are not typically addressed effectively through psychoanalysis.