A mental illness is a brain disorder that causes an individual to think, act and feel differently to other people. It is quite common for the disorder to disrupt a person's whole life and prevent them from going about their day normally without thinking these disturbing thoughts. Unfortunately nobody has been able to establish a direct cause for why mental illness affects up to 30% of the British population. There are some common factors thought to influence its development, for example genetic inheritance and social causes but no one knows for sure because each case is different.
Some common mental disorders such as depression and anxiety affect an individual's emotions and the way they are feeling, less common illnesses like schizophrenia affect the way a person thinks. It is extremely important to understand that a person with a mental disorder cannot just stop the way they are thinking, feeling or behaving; these illnesses can take control of the individual and disrupt their lives.
Most individuals with a mental illness are embarrassed about their thoughts and don't want to seek help or tell anyone about it, however mental disorders are very common and there is a great deal of help available to those suffering.