All mental illness is a sickness involving changes in thoughts, emotions, beliefs, or behaviors, and they stem from a combination of chemical imbalances in the brain, brain structure abnormalities, and personal history/environment. It is not something you choose to have, and we’d all cure ourselves if that was possible. No one would choose this.
Something qualifies as a mental illness if your thought processes, beliefs, perceptions, emotions, or feelings cause you so many problems operating in daily life that they preclude you from living normally. Mental health, like so many other things in the human condition, is a spectrum (gender identity and sexual orientation are good examples of natural human spectrums), so having a few symptoms of a mental illness does not automatically make you mentally ill. If the symptoms you are having are severe enough to get in the way of normal functioning, you then have a mental illness. An example:
If you are depressed for a week, but can still operate well enough to shower, drive, converse, feed yourself, sleep, and go to work, then you are depressed, but not disabled by depression. You still may be in a lot of pain, but this is not enough to diagnose you with Major Depressive Disorder, since it’s only been a week and you’re still functional. You are having symptoms of depression, which sucks very much, but you are not technically mentally ill.
If you are depressed for two weeks, cannot get out of bed during the day except to use the bathroom, can’t eat, have trouble sleeping at night, can’t take showers, or don’t leave the house, these are all signs of severe mental illness, and would probably net you a diagnosis of clinical depression as well as one or more psychiatric prescriptions. The difference between the two examples is that in the first, you are depressed, but still functional, and in the second, you are clinically depressed and have lost pretty much all functionality.
One is considered ill by doctors if they have lost some of their ability to function. This loss of ability to function is what causes some mentally ill people (like me) to be disabled. While many mentally ill people do perceive the world differently from the norm sometimes due to delusions or hallucinations, that is not a universal trait of mental illnesses. A common, near-universal trait of mental illness regarding world-view would be having increased empathy and insight into the human condition, which is not an unhealthy or abnormal quality for a human to have. Some mentally ill people have a very normal world-view. Others do not. Depression, anxiety, and PTSD are good examples of mental illnesses that could allow a fairly normal world view. Bipolar, schizoaffective disorder, and schizophrenia can (but do not always) build a very unrealistic world view, due to delusions and hallucinations, often only for the duration of an episode. However, once the episode is over, a “normal” world view is restored, unless an individual has delusions that never go away, regardless of being in or out of an episode.
Our thoughts and feelings stem from our brain chemistry, brain structure, and personal emotional history, and so do our mental illnesses. Post-Traumatic Stress Disorder (PTSD), for example, stems from trauma in the past (personal emotional history) that has changed brain chemistry and/or brain structure to the point of causing intense fear responses or flashbacks in certain situations. Depression and anxiety stem primarily from brain chemistry. Bipolar disorder stems from brain chemistry and brain structure.
We are at the mercy of the brains we were born with. This is often very unfair. No one who has a mental illness gets to choose it. Fortunately, our modern world contains doctors who can medicate us well enough to make life livable, and we can combine this resource with therapists, who can teach us how to live in less pain. The treatment of mental illness, both through medication and therapy, attempts to resolve any problematic emotions or behaviors that are present, which is a wonderfully healthy goal.
There is a large misconception that mentally ill people are weak, and could fix themselves if they had enough willpower. Mentally ill people cannot think their way out of their mental illness. They are considered ill because their symptoms, caused by problems or abnormalities in their brains, cause them to lose their ability to function normally. On an individual level, the causes of mental illness have nothing to do with willpower or wrong thinking. Mental illness does not occur because of lack of willpower or personal weakness. It is an illness in the brain, which is a part of the body, and has to be viewed as such.
By Emily Harrington, The Goldfish Painter