Manic depression, also known as bipolar disorder- which is the newer, more politically correct term, is made up of feelings of extreme unhappiness and
mania.
Symptoms for mania include euphoric feelings, cheerfulness and a great sense of self-esteem. Speaking rapidly and frequently and needing little sleep
are other manic depression symptoms for the mania cycle. Manics will also give little regard to their spending habits, and will have delusions of
grandeur. Racing thoughts, being easily distracted, and over-indulging in pleasureable activities are also symptoms of the manic phase.
The depressive phase is characterized by too much sleep, over- or under-eating, feelings of sadness, "the blues" or hopelessness, and suicidal
thoughts.
Manic depression tends to be genetic.
Psychopathy is usually associated with antisocial personality disorder. Symptoms tend to include a sense of entitlement, unremorsefulness, apathetic
to others, unconscionable, blameful of others, manipulative and conning, affectively cold, disregard for understanding of behavior and socially
acceptable behavior, disregardful of social obligations, nonconforming to social norms, and general irresponsibility.
Schizophrenics have symptoms such as hearing (internal) voices not heard by others, or believing that other people are reading their minds,
controlling their thoughts, or plotting to harm them. These symptoms may leave them fearful and withdrawn. Their speech and behavior can be so
disorganized that they may be incomprehensible or frightening to others.
A psychopathic schizophrenic, I assume, would have the symptoms of both, although I have not personally come in contact with someone diagnosed as
such.
The National Institute of Mental Health has some great resources available regarding the illnesses you have
mentioned.
Feel free to contact me via u2u if you have further questions.