Paranoia, hallucinations, and schizophrenia are all words that people associate with mental illness. In David Auburn's Proof, characters display these signs and more. Mental illness is a combination of environmental and hereditary factors that can affect a person at any stage of life. Catherine and Robert appear to exhibit signs of mental illness after speaking to her father after he progresses to Robert's graphomania and hallucinations. Mental illness is a theme that resonates throughout Proof. Mental illness is a debilitating illness that affects the mental stability and sanity of characters. Mental illness is something people don't like to talk about because of the stigma associated with it. Mental illness is a common, but poorly understood, medical condition that alters cognitive, mental, and social skills. Some common mental illnesses include depression, obsessive-compulsive disorder, bipolar disorder, and schizophrenia. These illnesses and disorders can affect many aspects of a person's personality and change their mental abilities. Some of the main causes of mental illness are genetic, traumatic and environmental. Genetic mental illness is contained in a person's genetics and travels through the genes. This mental illness is transmitted from parents to children. Traumatic mental illnesses, like PTSD, affect many people but are common among military men and women. Traumatic events can change how the brain functions. Anxiety, insomnia and rage are common symptoms of this trauma. These brain changes are not permanent and, with therapy and treatment, the damage is reversible. Environmental mental illness is a very common mental illness linked to environmental factors like drugs...... middle of paper ...... uh, Catherine's mental instability is due to the enormous amount of stress she experiences and the difficulty she finds herself in. she strives to prove that she is a good mathematician like her father. Mental illness is a debilitating illness that can take a toll on an individual and their family. Mental illness is also a major theme in Proof, and readers find that the main characters exhibit signs of mental illness. Robert's mental illness, although never revealed, affects his mind and way of thinking. Catherine, on the other hand, may not have a mental illness problem, but rather a problem with excessive stress. Catherine is under stress caring for her father and living up to his legacy. This stress is enough to affect long-term mental stability and can change the way a person's brain functions. Catherine's stress could manifest as a mental illness-like condition..