what are the biological influeneces on the memory with people who have schizophrenia

Georgeann - Thanks for your question and concern for your friend.

Schizophrenia is a chronic, severe, disabling brain disorder that interferes with the way a person interprets reality. Since schizophrenia affects many different areas of the brain it causes a wide range of behavioral, emotional, and intellectual symptoms. The cause is unknown but problems with brain structure and chemistry are thought to play a role. There also appears to be a genetic component. People with a parent or sibling with schizophrenia have a 5%-10% chance of developing the disease. This compares to a 1% chance if no relatives have schizophrenia.

Memory loss is not a typical symptom of this condition but it is possible that your friend may experience memory loss as part of the illness since it has such a strong impact on the way the brain functions. Disorganized thinking, along with disorganized speech, are common as well as delusions and hallucinations.

The psychiatric community has long debated whether schizophrenia and bi-polar disorder are related, and whether a genetic link is involved. Many patients have similarities in symptoms that are characteristic of both, such as manic mood swings in bipolar disorder and psychosis in schizophrenia.A major study was done on this in 2009, and you can read about the study here:
http://www.medpagetoday.com/Psychiatry/Schizophrenia/12480

Psychiatrists have specific criteria they use to determine which illnesses their patients have, so your friend would need to be evaluated professionally to determine whether or not she also has bi-polar disorder.

The National Institute of Mental Health provides comprehensive information on both conditions, which you can find here:
http://www.nimh.nih.gov/health/topics/schizophrenia/index.shtml

http://www.nimh.nih.gov/health/topics/bipolar-disorder/index.shtml

Please let us know if we have answered your questions, and if you have additional concerns.

Take care, Pat