mind/body again

I want to be a psychopharmacologist. I'm on drugs right now that affect my neurochemical functioning.

I have always found it confusing to think about this boundary though. I told you I'm a dualist, that I recognize some distinction between myself and my body. But when I design drugs that change neurological functioning, at what point am I righting something that was "wrong" before, and at what poing am I altering the fundamental nature of the personality? Mental disorders, for instance, can be partially rectified with medication. But what am I changing? Am I fixing a malfunctioning neurotransmitter process, or am I actually altering the personality, changing the person? It is obvious that chemical changes caused by drugs affect the "mind" in the form of changing emotion, concentration, etc. Where is the line?

I guess that is the problem with Cartesian dualism. There has to be a line, and who knows where it is? I don't think it's right to drink caffeine or to use LSD because I think it alters me unnecessarily. But aren't the drugs I'm on altering me too? And why do I feel like they are providing me a way to be my essential self? Aren't I just changing my essential self by taking them?

We live in a world that claims to be mostly (scientifically at least) material, but even in science there is evidence that people don't truly believe in the absolute mapping from mind to body. If so, how would we have an identity at all? And like the Cartesian argument for existence, how can we not have an identity if we are capable of questioning its existence?

People with disorders that result in rapidly changing, constantly inconstant mentalities like schizophrenia, bipolar, borderline personality, dissociative identity, report a loss of continuity of self. But what is self but a collection of ultimately quantized chemical states? There really is not a thread of connection. There is constant chemical flux. So if there is such thing as a sustained identity, how does it arise, and how do we explain the constantly changing identity of people with constantly haywire neurological chemistry?

And yet, if there is no self, why the accute feeling of loss when a disorder like that triumphs? One must have once felt something like continuity of self to notice its lack.

All so confusing, so so confusing.