I was diagnosed with severe depression. I take my medicines diligently. Will I ever fully recover? Will the disease recur? I was told that once you get a mental condition it becomes like a terminal disease.
First, let me congratulate you for following the advice given to you by your doctor. More than anything else you might do as you continue to recover, this acceptance of the professional advice you are receiving, is most important.
Additionally, whatever I tell you about your condition, remember I am not your doctor, and because I have not examined you, my opinion is general based on my experience. Only your doctor will have the final medical opinion in your case.
This caveat is important in evaluating the value of opinions offered by well-meaning but uninformed friends and relatives. Similarly, the internet has information that one might need to verify by discussing it with a doctor.
The first part of your question enables us to make this point. You ask, “Will I ever recover” and you continue to ask, “Will the disease recur”. The truth is that only your doctor will be able to answer this question in your particular case. In general, the reality is that the correct answer is that it depends on many factors.
For example, if you are 18 years old and went to the hospital for depression treatment for the first time following the death of a friend in a freak swimming accident, and you have no risk factors like a family history of depression, you do not take drugs, are a good student and you have a good family support system, the doctor might tell you that you have a good chance of making a full recovery provided you follow the suggested health promotion activities that he might suggest.
If on the other hand, you are a 50-year-old man who was admitted to hospital for the fifth time this year, and you have a recent history of hospitalisations for chronic alcohol abuse, you live alone and you have no social support system from anybody, the chance is that yours will be a chronic condition whose outcome will be uncertain.
Somebody told you that once you get a mental condition the condition becomes like a terminal condition. It is unlikely that this opinion was given by a person with knowledge about mental disorders and depression in particular.
Whereas in some cases depression goes on to become a chronic and sometimes relapsing condition that might, like other medical conditions require lifelong medication, there are many people for whom depression is easily managed and people continue to live completely normal lives.
In your case, the fact that you are “diligent” in taking your medication tells me that there are good chances that you also take your doctor's advice seriously on other things he might tell you as being useful in preventing a relapse.
You might for example have been advised to reduce alcohol intake as well as advise on regular sleep patterns. You might have been made aware of the importance of regular exercise on your mental health as well as learning how to deal with interpersonal conflict, including the importance of the early resolution of say, marital strife.
As you can see, there are very many factors that influence what outcome one gets in cases of depression and it is true that not all cases have a bad outcome and equally, not all cases have a good outcome.