Probably doing anything regularly for long term will have some effect on the person. If you run regularly for a long time, your body gets used to the running. It affects the body both physically, psychologically, and hormonally. The exercise affects hormones, and the running becomes a regular part of the person's life. If the person stops running, they will feel different. They'll feel like something is missing, maybe feel restless and anxious. That's just the way it works with EVERYTHING. The body gets used to certain things, and notices differences when there are changes. It's constantly adjusting to maintain homeostasis. If you've had a job your whole life and end up out of work all of a sudden, you will probably find yourself in a fog for quite some time. It may feel like something is seriously wrong with you, but your body is just adjusting to the change. Point is, everything has an effect.
Having said that, I have only noticed positive physical and mental effects after taking dmt. The positive physical effect is due to the rejuvinating state of relaxation. It is very refreshing like getting a good night's sleep. I feel ready for another day. The positive psychological effect is an enthusiasm for life in general, and the mystery of existence. I feel more ready to interact with the world, and I appreciate my life. However, having said that, the psychological effect will not be the same for everyone. I think some people just break, or freak out when presented with unusual experiences. DMT has facilitated my psyche to bend, not remain rigid and break. I have learned to not make assumptions about what I experience, not pretend to know any objective answers. I have learned to allow what happens and just let it be, and enjoy it. I'm talking about all of life, not just the psychedelic experience. The same won't be true for everyone. I think some people may be more likely to cling to what they experience. If people can't let go of a certain idea, that idea will pervade their psyche and make them afraid. If you allow yourself to be bent, you will be ok. If you remain rigid about your experience, any experience for that matter, you're more liable to break. It's possible, but it seems most people here anyway have positive experiences with dmt. It's a powerful tool. For some people, skydiving might be a thrill, but for others, it might be traumatic. DMT is not for everyone.
As for long term effects, I don't know of any long term negative effects that have been consistently recorded, and haven't experienced any myself. I can't say I experience any objective changes. Even there were any objective changes to physiology or neurology, my body has adjusted. My homeostasis has not been compromised, and my ability to function in the world certainly hasn't been diminished. The changes are more subjective than objective. I see more beauty in the world, and in simple shapes, and my imagination seems to flow more freely, and I find sleep more peaceful, and am happier in general. All good things. Apparently, some people report HPPD after taking psychedelics, although for some reason it seems less commonly reported with dmt use. The symptoms are usually reported to subside if the person stops taking psychedelics. I have never had any hppd like symptoms. Also, even if you do find yourself having negative symptoms after use, then just stop using it. It's not addictive, and you won't want to do it if it makes you feel bad.
So, to summarize, there doesn't seem to be any universally accepted physical harm done to regular use of dmt. Psychological issues will vary from person to person (just like anything else). Most people seem to be fine. Nothing is guaranteed though. You're dealing with a substance that has a powerful effect on consciousness and perception. It's up to you if you want to take the chance to experiment with it. I mean, legally it actually is not up to you what to put in your own body. That should be a basic human right, but unfortunately, it is not yet. As it says in the nexus wiki, "DMT is a bottomless well of never ending confoundment, an unsolvable riddle of epic proportions spoken in alien tongues. It will call into question all that you know, all you’ve learned to accept as reality, and introduce you to a state of being which defies all comprehension." The potential effect of dmt is that you question all of reality. ALL of reality. The ramifications could be anything. It's up to you if you want to touch something potentially so powerful. As for me, something in all these experience reports will resonated with me. There was something about the way all this stuff was written, and the general accepted safety of psychedelics that led me to conclude after much research for myself, and by myself, that this was something I wanted to try because there is much to be learned in the adventure of life. I asked all these questions before I took a trip as well.
) I will want to use it over the course of my life, hopefully, without any downsides decides the fact that you can encounter some scary shit whilst tripping. Also, I have an addictive personality. When I first launch I will most likely want to launch again pretty soon after (3 to 4 days, is that normal?) until I've become well aquainted with the molecule and can figure out how to integrate it into my lifestyle without a negative effect on me. 
