I encourage having a look at the September 2016 issue of The Canadian Journal of Psychiatry, which summarizes treatment recommendations for major depressive disorder, based on a thoughtful review of the evidence available at the time. The authors spent many hours of careful work preparing this authoritative set of articles, and I think they did a good job.
Here is a brief summary:
1) Various antidepressants are beneficial for treating depression. They may help with an acute episode, and may help prevent relapses if continued. Some may work better than others, but the differences are small, and there are likely to be individual cases in which a so-called "second-line agent" works better than the first-line choices. Some things are classified as "second-line" not because they are necessarily inferior, but because they have not been researched as much as the "first line" things.
2) Various types of psychotherapy are beneficial for treating depression. These, too, can be helpful for acute episodes, as well as for preventing relapses, even after discontinuation. CBT has particularly strong evidence for being effective.
3) As to specifics, such as "which medication is best under which circumstances?" or "which type of psychotherapy is best under which circumstances?", the evidence often does not guide us clearly, aside from CBT in general being favoured.
4) Various other types of treatment, including ECT, TMS, exercise, and light therapy, have evidence supporting their use.
I am concerned that there was not a lot of critical debate about these claims. Many authors of review articles are proponents of a particular type of therapy (e.g. light therapy, CBT, etc.), and the content therefore may be biased, or at least lacking input or commentary from different points of view. It could be argued that "the data speaks for itself," but often the verbal conclusions resulting from the data can be coloured significantly by the author's opinion.
There are some useful specific pointers: for example, there is a lack of evidence that combining two different antidepressants is consistently helpful. But "augmenting" strategies, such as adding an atypical antipsychotic medication to an antidepressant, are better supported by evidence.
In general, for me, these guidelines are most useful as a very general introduction, to get an overview of common treatments, and of up-to-date research evidence.
Here are some ideas of my own to add about "treatment guidelines":
A very thorough understanding of a person's history is most important for care. In many cases what appears to be "major depressive disorder" ends up being a more complicated story, upon spending time learning the history. Many treatments such as antidepressants can be dangerous if given without thorough understanding of the history (for example, if there is a history of bipolar symptoms). Obtaining a good history is not necessarily possible with a single visit, with a standardized interview, etc. It takes time and a good therapeutic relationship to know a person's story.
There is some question about the validity of "major depressive disorder" as a construct. Eiko Fried has a good summary of this issue on Twitter: https://twitter.com/EikoFried/status/935098850439847937
As I have written before, a great many patients do not have only one diagnosis (assuming we are focusing on a DSM-style diagnostic scheme). It is therefore limited to focus only on the treatment of depression alone. I realize that it is a convenience in research to define syndromes in this way, which can then help us to measure the effectiveness of treatments systematically. But for a given individual, it is often necessary to step away from diagnostic constructs, and help the person in the specific ways they desire or need.
There are many pathways towards nurturing mental health. Finally it is reasonable for most people with depression to try various treatments, including medications, provided there is a good understanding of risks and potential benefits. Psychotherapeutic ideas (such as CBT, but also other styles) are beneficial for most anyone, even those who do not have formally diagnosed mental illness. Lifestyle and psychosocial factors are very important: exercise, healthy nutrition, healthy social, family, and community development, physical safety, career, education, stable finances, and the pursuit of meaning, should be an invited focus for everyone. There is relatively little attention given to these issues in most published treatment guidelines (sometimes I get the feeling that some authors in the field are embarrassed to even approach them) yet for many people these issues are the most important of all.
In the 102 pages of this journal, which are devoted to approaching and treating depression--a disease of emotional and often existential suffering, loneliness, joylessness, and a crisis of meaning--here is a tally of individual words used in these pages:
1) love: 0 times. The search engine found a reference to the author J. Glover as the only occurrence of "love"
2) compassion: 1 time
3) nutrition: 1 time
4) cooperation: 0 times, except as part of 7 references to an agency (the "Asia Pacific Economic Cooperation") which gave money to one of the authors
5) healing: 1 time
6) friendship: 0 times
7) encouragement: 1 time
8) pets: 0 times
9) nature: 1 time (referring to "nature of risk")
10) joy: 0 times
11) humour, laugh, laughter, smile, happy, happiness: 0 times for all
12) art, hobby, hobbies: 0 times
13) patience: 0 times
14) drug: 86 times
15) intervention: 91 times
While I love science (my alternative career would have been a mathematician or a statistician!) it is necessary in mental health care to also discuss issues or words that do not fit neatly into a science or data-based analysis. These issues include compassion, meaning, love, and patience. Another issue is finding ways to cope with, live with, or accept unremitting chronic illness or pain, while continuing an evidence-based, but uncertain and frustrating, search for relief or cure. Algorithms and guidelines tend not to help very much with this existential struggle. Educationally, I think it is more valuable to present case studies, with group engagement, perhaps with references made to treatment protocols, rather than to make the protocols themselves the subject of the lesson.
I prescribe a lot of medication. In some cases the medication appears to be incredibly helpful. In many other cases, there is a small but significant benefit. And in others still, there is not much benefit at all despite many, many trials of different medication. And in a few cases, the medications are harmful. Many of my patients benefit most from medications that are considered "second line." I can't think of any examples in my practice where guidelines of this type have been useful in determining the most helpful course, aside from being a very general roadmap to remind us of available options or the occasional new finding in the research. But this roadmap would already be very familiar to most mental health professionals, part of an academic focus over years of training. Specific treatment issues (such as choosing the best medication or psychotherapy combo etc.) are part of professional development: this requires ongoing familiarity with the broad research literature, and with experience in clinical practice, rather than reliance upon review articles. Review articles of this type are authored by research experts, whose work deserves respect; however, the authors represent a limited subset of expertise within the population of mental health workers.
My therapeutic style has included more and more ideas based on CBT, over the past 15 years. Many of my patients work on structured CBT elsewhere as well. As with medication, this is incredibly helpful for some, slightly helpful for many, and has little or no effect for a few others. Arguably, some CBT groups could even be harmful for a few, if there is a large mismatch between what the person desires and needs and what is actually offered. In many cases, people are familiar with these therapy styles, but have not yet really done the work necessary to derive benefit from them. This lack of work is usually due to the depression or the psychosocial situation itself, but also can be due to a lack of continuity of care. It can be a little bit like trying to learn a foreign language, and dabbling in it for a few months, learning a bit of grammar and vocabulary, but never really gaining fluency due to a lack of immersive focus, and a lack of someone to speak the language with on a regular, long-term basis.
Many people, I think, simply benefit from knowing that they are being cared for, by a person or system which has time and attention for them as they need and desire, sometimes on a long-term, open-ended basis. It is helpful for mental health care providers to be well-versed in a wide variety of therapeutic techniques, and to be able to adjust or tune the care to what each individual patient or client wants or needs. Within a system, it is good to value the unique styles and abilities of different individuals within the group, rather than compelling everyone to follow an identical protocol. Some caregivers are better-suited to using a CBT style, while others are naturally suited to IPT, meditation, or psychodynamic styles. Some psychiatrists have a particular expertise and interest in medication management. Most research protocols do not look at this issue in groups or systems. These individual variations should be respected, but I do think it is also good for everyone to come together to learn from each other. For example, psychodynamic therapists can adopt interesting, useful ideas from CBT therapists, and vice-versa.
Most of my patients would say that it was not some medication combo or therapeutic style or adherence to guidelines that ended up helping them, but was a combination of many factors, in conjunction with a system of care (such as a therapist, psychiatrist, or other support network) which was stable, consistent, compassionate, and long-term.