Is It Necessary To Take Medications For Dysthymia Depression Lifelong?

Hi I m 23yr old girl passed my BDS last year. On medication for dysthymia depression since last one year. Took various medicines in this span. Have observed constant improvement with the course of medication. Currently take lamitor OD 100 & depsonil 75 from last 4-5months. My doc has added nuhenz recently. As I skipped doses for last few days I m having extreme dullness & fatigue again moving towards dysthymic phase of depression. I wanted to know what s exact correlation between medicine which stimulate endorphin release or trigger activity of neurotransmitter...& body s deficiency to allow working on its own..? Is there any permanent deficiency/damage to body s natural mechanism? Do I l have to continue medication lifelong as in the case of diabetics who have to take insulin injections life long?