Harmaline hydrochloride dihydrate is primarily used in research settings for its psychoactive and neuropharmacological properties. It acts as a reversible inhibitor of monoamine oxidase A (MAO-A), making it valuable in studies related to neurotransmitter regulation and the treatment of psychiatric disorders. Its ability to modulate serotonin and dopamine levels has led to its exploration in understanding mood disorders, depression, and anxiety. Additionally, it is used in ethnopharmacological research to study traditional medicinal practices, particularly in the context of ayahuasca, where it plays a significant role in the psychoactive effects. Its application in neurobiology also extends to investigating neurodegenerative diseases and potential therapeutic interventions.