Why is it that some people have a psychiatric disorder and they bounce back and it’s not a big deal, while others struggle terribly? For the unlucky ones, mental illness defines them.

Here are some factors that affect how much impact psychiatric illness has in a person’s life.

• The severity of the symptoms. Any way you dice it, mild-to-moderate anxiety can often be hidden and isn’t as disruptive as an episode of psychosis with hallucinations and paranoid delusions.
• The duration of the episodes. So a chronic depression or severe obsessive compulsive disorder may be more disabling than a brief episode of psychosis.
• The form of the symptoms. Some symptoms are intrinsically more public than others, or more difficult to bounce back from. In terms of “Can I be a doctor if I have bipolar disorder?,” one episode of walking around the hospital naked may be all it takes to get sent home. Form and severity of symptoms, and the duration of the episodes, are likely to be intrinsic to the disease and not something the individual controls.
• How responsive the illness is to treatments. Some people have very severe symptoms that are very responsive to treatment.
• External support systems: access to good care, chicken soup, and TLC. Job flexibility may enable some people to quietly take time off when the going gets rough. Understanding friends and family — these are all good things.
• Individual personality features that support good coping. This is vague and I just made it up, but it’s the best I can do — maybe “resilience” is another term for it.
• Individual special features which help a person compensate. So being extremely intelligent, or extremely efficient and diligent, or very charming and charismatic, may make everything else a bit easier.
• Stress load. This is hard to say for all people — many people really struggle when things go wrong, and not all people with psychiatric illnesses relapse under severe stress, but all things being equal, it’s probably better to not have a lot of loss and stress in life if one is trying to cope well with mental illness.
• Co-morbid substance abuse. People with psychiatric disorders and drug or alcohol addictions just don’t do as well. Often, it’s a toxic combination.
• Co-morbid medical disorders.
• A willingness to devote time, energy, money and resources to a healthy lifestyle. It can’t hurt.

Dinah Miller is a psychiatrist who blogs at Shrink Rap and co-author of Shrink Rap: Three Psychiatrists Explain Their Work.