It's important to identify what causes a mental disorder so that the best treatment can be determined, but it can be difficult to determine which factors within a person have the most influence.
One way to highlight this issue is by considering the debate of nature vs. nurture. Which one of these has the biggest effect on psychological development?
Nature refers to any innate biological and genetic factors that a person is born with or that they develop normally over the course of their lives. These characteristics represent the internal factors that are difficult for a person to influence in any way because they are something a person is born with.
A mental disorder that relies heavily on the nature aspect is psychopathy or sociopathy. This refers to someone who is psychotic in some way. Originally, a lot of psychologists thought that this was due to a person's abusive childhood and that early mental trauma was what actually caused the development of these mental disorders.
Recently, though, findings have shown that there are many innate genetic factors that contribute to the development of sociopathy. A person who has a normal childhood can still develop psychopathy.
Nurture pertains to the environmental factors that shape a person. This includes influences like the culture a person grows up in, their childhood, their parents, early developments within their life, and any significant life events that might cause mental injury or shock in the person.
Psychological trauma are negative psychological effects that cause large amounts of stress on a person, often resulting from violence, abuse, neglect or any extreme stress that the person might have endured.
EXAMPLEA phobia is something that develops due to nurture. Major or unfounded fears of something typically form due to some traumatic experience.
Another example would be post-traumatic stress disorder (PTSD), which is a disorder that develops as a result of severe psychological trauma.
EXAMPLEWhen soldiers return from a wartime setting, often the trauma of being within that setting causes them to develop this particular mental disorder.
The psychologist Donald Hebb once answered the question about which one is more important (nature or nurture) by posing the question, "Which contributes more to the area of a rectangle, the length or its width?" By this he meant that both of them were equally important; similarly, we need to consider both nature and nurture in order to have a full picture of psychological disorders.
The stress-vulnerability model is a theory of psychopathology which states that the cause of mental disorders is a combination of both biological and environmental approaches. Based on this notion, people are born with certain kinds of genetic susceptibility to a mental disorder, but it doesn't actually develop unless that person is exposed to some environmental stresses or psychological trauma.
EXAMPLESchizophrenia has been shown to have a large biological component, but environmental factors are also related to its development. Factors such as prenatal nutrition, early childhood trauma, and family environment can all lead to the development of schizophrenia.
Source: This work is adapted from Sophia author Erick Taggart.