It definitely has a major effect for me. I take two capsules (400 mg ea <to be confirmed>) with the morning meds and sometimes take a similar dose in the evening.

Traditionally one would periodically drop it to allow the body to "reset" itself and I try to skip a day every now and then.

There is definitely more than a neuroprotective action at work in that there is a noticeable short term action on symptoms. As to what is actually going on, I will hazard a guess but that is all it is -

Ginseng has a reputation as an "adaptogen" which is just what the name implies. It helps you adapt to stressors upon the system. That means an effect on the HPA stress centers which translates into stabilizing the fight or flight merry go round and the steroids that go with that. The steroids are a long term danger but they and their breakdown products are also neuroactive and act as neurotransmitters like dopamine, serotonin, etc do. That's why stress knocks us out - along with dopamine being used for producing some of the stress hormones as well. Ginseng stabilizes the whole structure somehow. I repeat, that is a hazardous guess

Another thing that I ran across just an hour ago that may be relevant to that explanation is that blacks with asthma are much less responsive to the steroids that are used to treat it. It is also known that blacks are much less likely to develop PD. It could be that their lower sensitivity protects them from PD and in whites a heightened sensitivity to steroid hormones increases our vulnerability.

If that is all true, then adaptogens make sense.