What is the difference between mental illness and mental retardation?

Mental illness usually develop as an otherwise healthy person grows. Mental retardation is a congenital defect (before birth) that retards, or holds back, mental development, like motor skills, life skills, reading skills, etc. Mental illness can be treated with drugs and therapy. Mental retardation cannot be reversed.

you acquire a mental illness. You're born with retardation. Mental retardation is genetic.

Direct merchant is wrong, it is genetic, but you can also acquire it from brain damage. Mental Illness is like depression.

The first is usually psychological in origin. The second is usually physiological in origin.

mental retardation is when an individual lacks intellectual funcioning generally determined by an intelligence test

mental illness has to do with a person's coping abilities and the problems that result in their attempt to control their emotions/feelings

With the understanding that I am not a mental health professional but have had quite a lot of interraction with people who would be classified as mentally retarded or mentally ill --

Mental retardation is a specific condition in which the sufferer's mind is not able to develop in a normal time frame and in a normal way, resulting in a dramatically lowered IQ and emotional responses akin to those that would be expected of a much younger child (to "retard" something is to hold it back or delay it -- from the same root as "tardy" meaning to be late). It is a developmental/learning problem. It can be the result of a genetic defect, but it can also be caused by injury or illness that damages the brain especially at a young age.

Mental illness is a much broader term, generally referring to a mind that develops normally in terms of learning abilities, IQ, emotions, and so on, but which does not process reality in the same way as a "normal" person. Some forms are primarily genetic and thus run in families, but environmental stresses and upbringing are the major factor in other types. I don't know if it can be brought about by injury or physical illness, I've never heard of such a case but I guess it could happen.

So you can see, this is sort of like asking "what is the difference between an airplane and a 1966 Ford Mustang" -- not only Mental Illness and Mental Retardation different types of conditions affecting the brain (just as airplanes and Mustangs are different types of transportation), but one is a general category while the other is a specific example (there are lots of types of airplanes, many being radically different from one another, but only one kind of 1966 Ford Mustang).

Mental illness encompasses such conditions as schizophrenia, Obsessive-Compulsive Disorders, depression and manic depression, manias, phobias, post-traumatic stress disorders, and the like.

Most mental illness can be treated at least to some extent by drugs and in some cases through behavior-modification techniques, because it is generally a malfunctioning of specific neural paths in the brain. Mental retardation, on the other hand, cannot be treated by either.

Many of the worlds brightest people suffered from one form of mental illness or another, to some degree. There is an old saying that "Genious is looking at the same world everyone else looks at, but seeing it differently" and the mentally ill definitely see the world a bit differently from "normal" people.

Probably more than you ever wanted to know, right? ;)

Mental retardation is assessed through IQ testing. It means the person has a low IQ which impairs their functioning, so they may need special classes at school or jobs that are not very demanding. Mental illness refers to a wide range of disorders including anxiety, depression, schizophrenia, OCD, and Alzheimer's. They are disorders that can be genetic, learned through behaviors, or results from brain trauma. Usually they are treated with therapy and possibly medication. Mental retardation is treated through accommodations at work and school, like less work load.