I would argue that is because things are in reality way more complex than "low level equals symptoms". Biology is messy, lots of systems are interrelated, there's different target sites inside and outside the brain, different brain circuits that sometimes agonize and sometimes antagonize, different receptor types. Different ways in which neurotransmitters cause or facilitate or hinder reactions. More on reddit.com

There's a relationship between dopamine levels and the responsivity of dopamine receptor neurons; as far as I remember, too much dopamine over a long period of time will cause more and more of those neurons to deactivate, because the brain doesn't need (or want) as many neurons to stay active, the remainder can do the necessary level of work all on their own. Which means when you lower the amount of dopamine overall, a lot less gets received since there are fewer neurons left, working with a smaller input. It's meant to be a self-balancing system: it fries itself out. I'm oversimplifying because it's been a long time. Do your research though, I'm sure there are new discoveries in the last 3-5 years worth looking into, maybe some help on how to recover from burnout exists by now. More on reddit.com

I think that you ll find a lot of those supplements in the ADHD posts as ADHD is also attributed to less Dopamine in the brain and that you get a lot of addiction among ADHD people. Other suggestions : 5htp + EGCG in the evenings .... Over the long run dopaminergic supplements deplete serotonin. To avoid serotonin syndrome take it with EGCG a better choice than EGCG is just taking a matcha tea. You will clearly feel a difference as you will feel more of a loving attitude. Coffee + L Theanine. This is very much documented. Coffee definitely increases dopamine. Make sure you take a light coffee! Or even better and a better feeling in my opinion Matcha tea + Ltheanine. Ltheanine increases BDNF and therefore brain repair Much less obvious and less documented but nevertheless efficacious : Psilocybin : it is a very powerful anti inflammatory that increases brain plasticity. People forget that psilocybin is a stimulant. It also takes care of the loving feeling. It also increases BDNF. There is a paper about treating ADHD with psilocybin. There are many papers for treating drug addictions with psilocybin. Of course if it is accompanied by psychotherapy it is even more powerful at treating addiction. Many serotoninergic supplements increase brain plasticity and therefore repair. Post Edit : There are also the very well known and documented magnesium ( L Threonate ) and phosphatydilserine Much love and good luck to all redditors struggling with addiction ADHD ...mental issues More on reddit.com

Complicated. One likely etiology is the decrease of dopamine following an expected reward which is not fulfilled. Dopamine isn't really a "reward" signal as much as it is involved in reward anticipation. Tonic dopamine actually drops when a predicted reward fails to materialize. This can have an impact on motivation and motivated states. One potential structure playing an important role is the lateral habenula. During a failure of reward this is one of the few brain structures to turn on. There may be some level of recursive control because a subset of VTA (a midbrain dopaminergic structure) neurons project to the habenula and inhibit it during reward. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3873746/ So some dysfunction of motivated behavioral states likely underlies it. Failing to respond normally where a rewarding stimuli could be anticipated is likely one piece of the puzzle. More on reddit.com