This is a significant topic. Thanks for raising it.
Depression is an illness of various degrees and often impacts the totality of the person involved...mentally, emotionally, relationally, sexually, spiritually...and physically.
One of the best ways to conceptualize this and make it applicable is in relation to "energy." Energy in excess, psychomotor excitation/agitation. Energy in depletion, psychomotor retardation.
It takes energy to do what we do...from thinking and paying attention, to eating, to brushing our teeth, to relating with others, et cetera. When energy reserves are low and failing, it is not uncommon to see this slowing down in what makes us human or in being alive.
Again there are degrees of this.
Personally, I have worked with some folks so depressed and so energy depleted that I literally had to be those patients "back up energy generator" for them....providing hands on direction in very basic functioning, like getting them out of bed, getting dressed, performing very basic hygiene, sitting them in front a plate of food and saying, "time to pick up the fork and take a bite and now a drink of milk." When a patient becomes this depleted, a staff member frequently needs to become a human coach for them. For the patient, thinking, feeling, and moving can become a very difficult process. And often it becomes very difficult "to feel good or think well about oneself" if simple things like eating, sleeping, basic hygiene and appearance (stuff we often take for granted when we have the energy) falls to the wayside. This can be seen in significant depressions. So as a nurse, I begin with these basic areas...functioning. Also, the basic act of "taking care of oneself" is often self nurturing...placing value back on oneself...which often takes a major dip during depression. In energy depleted patients, I have the focus start there...keep it simple, basic, self nurturing, and getting back into the routine of being human. Later, this same concept is branched out in connecting with others...relating outward once again.
I conceptualize my role as a nurse as being that person healthy enough in my own energy, which permits me in being able to lend that patient some of my own for awhile...until that person is able to kindle up some of his/her own spark and sustain it. It is almost like kindling a brand new fire from twigs...igniting the match, blowing on the sparks, providing additional fuel and oxygen for it to take hold on its own...to become an independent flame providing its own warmth.
Yes, depending upon the patient, it can become labor intensive at times...but so worth the effort. Actually, this is one of those wonderful occasions where a nurse can see the fruits of his/her efforts....the transformation of a patient from being almost zombie like into a living, more functioning person.
You ask if a therapeutic relationship is enough.
My friend, it is everything.