Is there even a method to determine brain damage from meds? Some meds can affect certain systems in the body so I guess it could affect the brain in negative ways too. But I've been in treatment for 30 years and I have never encountered anyone who claimed to have brain damage from meds. Even if it could be proven, I still say the gain probably outweighs losses.
One thing to remember is, with depression you tend to look inward more, and perhaps focus or even fixate on what's going on in your body. If you expect brain damage then I'm sure you will find signs of it. Just the very fact that you have a condition that might need meds or other medical treatment indicates there is already something wrong somewhere.
It's hard to convince someone that is convinced meds will hurt them, otherwise. I'm a believer in getting what ever help you need to get well or just be able to handle living day to day. I know I would have been insane or dead long ago if not for modern medicine.
***I'm pro-meds for me only. It is wonderful if some can recover from other means. It's just that some people read an opinion on the interwebz and take it as fact. RESEARCH, people!