I don't know about Benzo's contributing to Dementia, but a pharmacist told me that long term use of them can lead to short term memory loss, which is something I experienced form them. I was on clonazepam at a fairly high dose for close to 20 years. My Dr's were just going to leave me on them indefinitely because I was physically dependant on them, despite current guidelines against long term use. But I decided to come of it, and did a taper with the help of my psychiatrist. It took me about 18 months to come off it.

As for antidepresants I plan to be on mine for life. One of my Dr's put it this way "Whatever got you there, keeps you there" meaning that whatever dose/med gets you out of the depresive episode with help keep you out. That being said, I have hadd multlple episodes of MDD while on meds and I hate to think what would have happened it I hadn't had the meds on board.

With regards to antipsychotics, I'm on 2. One of them I've been on for about 18/19 years. I've tried to taper it down but the minute I drop it I get intrusive suicidal thoughts so I'm going to stay on my current dose long term. The second one I've been on for 10 years and it works really well for me, While both meds work for me, I do have side effects that are problematic. They've raised my blood sugar, but I'm not yet diabetic, I have EPS, and one of them makes me dizzy and sleepy when I take it. That being said, I feel that the benefit of being on them outweighs the negative side effects.