Using Zoloft.
Beginning at age 40 due to a stress filled life, I would have extreme dizziness with difficulty balancing for days to weeks. Initially thought it was from the particles in the inner ear and spent time trying to get the particles back in place and then relearning balance.
Fast forward to my mid 50s and going through a divorce and the frequency and severity increases along with my deep depression of going through the divorce. Began using Zoloft and depression lessened and dizziness went away altogether for several years.
After the divorce, came off the Zoloft and was fine until a stressful situation came up and the extreme dizziness came back. Went back to Zoloft and no longer have bouts with extreme dizziness.
No negatives to training. Especially since the extreme dizziness kept me from training, eating and sleeping well for days to weeks. Can currently run eight minute miles for 5K after cycling for an hour and then swim a mile while in my 60s.
Serotonin is in everyone's body. The quality or quantity of it can change as one get's older or stressed. Diet, rest, sun, etc. can help; yet, once a person is over the edge, like I was, using a serotonin based anti-depressant may help.
I can see where life can throw so much stress at a person and they can't just quit their job, can't get support from their own family or leave for the beach and change their diet enough to cope.
While running got me through my first life crisis while in my 20s, I was too stressed out by my 40s for it to help. My first extreme dizzy spell was after an enjoyable ten mile run while stretching.
The body breaks down due to stress and age and individuals try to piece together for themselves what works to keep their motor running.