A person's mental, and ultimately physical health is certainly affected by their way of thinking. If a negative outlook is a person's typical response to everyday life she/he is more likely to become depressed about negative outcomes than someone with a generaally optimistic mindset. We all have to face the occasional setback or rejection, but ruminating at length about the misery that has caused you will not help the situation and will inhibit or prevent opportunities for new incidents which could prove positive.
A person who constantly dwells on the unsuccessful aspects of his life and assumes the worst is unlikely to be good company or attract positive opportunities. How can such a person convince others that she/he will fulfil a task competently (or at all) let alone add colour to any social event?
The IQ of people unfortunate enough to be suffering from mental illness will follow the normal distribution for intelligence in exactly the same way as it does for people with no mental illness. However, there may be some tendency for those with extremely highly developed sensitivity to suffer in a repressive regime, for instance, or in the light of an understanding that is beyond the ordinary person.
Wonderful paintings have been produced by those suffering from psychotic episodes and suicide is perhaps more common in those with highly developed ability rather than those at the lowest levels of intellectual functioning
Mental disorder is a behavioral or mental pattern disorder that can affect how you think, your emotions, or your day-to-day behavior. There are many types of mental disorders such as anxiety, eating disorder (anorexia or bulimia nervosa), insomnia, bipolar disorder, depression and schizophrenia. There are also many causes to why a person has a certain type of disorder that includes stress, history of abuse, family history and biological factors.
It is not enough to depend on what you see on the internet because the information you will read there will not be enough. A person suffering from mental disorder should seek medical help to properly diagnose their disorder, and so he or she can get the appropriate treatment and therapy needed to reduce the stress or burden he or she is feeling.