The choice of the type of therapist can be quite daunting. The choices I will focus on are MD/DO, Psychologists, Social Workers and Clergy. While there are other options, I don't know enough about those choices to either be pro or con, so I will stay away from that type of discussion. You can go the medical route; for instance; a psychiatrist. Psychiatrists can be either M.D.'s or D.O.'s (Medical Doctors or Doctor of Osteopathy) in the US.
In choosing an MD or a DO, you can avail yourself of the various medications that a licensed MD or DO are allowed to prescribe. In certain jurisdictions, only MD's and DO's are allowed to prescribe medications to deal with psychiatric issues, due to the need of blood needing to be taken to make sure the drug is in the therapeutic range for the patient.
Be aware that trying a new drug to treat a psychiatric condition can take up to 8 to 10 weeks to get the medication in the therapeutic range. Patience is required for the patient to stick with the medication. There is one caveat. That caveat is unanticipated drug interactions, allergic reactions or an unwanted change in behavior that is detrimental to the course of treatment the patient is wanting to pursue.
One other thing to be very aware of is that sometimes medication is NOT an option when dealing with depression and the damaged brain. Most of the medications on the market currently, are for brains that have not been damaged structurally. If you have had a shunt placed for hydrocephalus, have had a stroke or a tumor pressing on a part of your brain that affects behavior, medication for depression may not work at all. For example, you would need to treat the tumor first and then see if there is a need for anti-depressant medication. You have to treat the problem first, and then the resolution will come.
Take a list of your current medications (including dosage amounts) with you to your appointment to make sure that your psychiatrist does not prescribe something that may have an adverse reaction with your current medications. There are certain medications that do not work at all well with psychiatric medications. If you are on one of those, make sure you inform your psychiatrist.
Psychologists are another route to go, when seeking treatment for depression. While psychologists have their place in the healthcare field, they are not medical doctors and can not prescribe medications, at this time. There are discussions going on to see if they should be allowed to prescribe medications, on a limited basis. Yet, what has been done is to have a psychologist refer a patient to a psychiatrist they work with for medication distribution. Psychologists can either have a Masters or PhD. A Masters program can take as little as 2 yrs after the four years in college. Whereas a PhD program can be 4-8 yrs after graduation from college.
Social Workers (usually they have a LCSW after their name among other initials) can work very well for people that do not need medication, but may need a different type of support structure to deal with issues. Noted, LCSW's can refer their patients to an MD/DO if they find the patient is in need of treatment options outside the realm of their licensure.
Though last on the list, clergy can also be a very good source of support and counsel when dealing with depression. Granted, clergy are not allowed to prescribe medications, their counsel can be just what the individual needs to resolve a conflict they might be dealing with.
