Since smoking effects capillary blood circulation by constricting the capillaries, I would expect it to have a negative effect on PCS.

It has other circulatory risks too so it should be considered a detriment to healing.

Those of you who are beyond the 6 to 12 months post injury time need to understand that further healing is statistically expected to be very slow. The quick healing happens in the first 6 weeks or so.

For those of you who understand half-life time lines, I would compare healing to a half life time flow. That means the amount of healing is halved for the same period of time as the preceding period of time.

If you healed to 50 percent in six months, then you may heal to 75 percent [50 + (1/2 x 50) ] in the next six months and 87.5 [50 + (1/2 x 50) + (1/2 x 25)] percent in the next six months. Depending on the severity of your injury, not the impact force, there may be a fixed point where healing stops. Nobody has been able to reliably chart out the statistics of long term healing except to show that there is always an unhealed residual from the injury. It may be almost imperceptible or it may be a considerable disability. The younger the person is at time of injury, the greater the chance of healing.

The half life term varies as does the residual unhealed component.

The best advice is to treat your whole body as if it is recovering from a severe illness. Good nutrition, no toxic chemicals (alcohol is a serious problem), good sleep habits, reduce life stresses and no further impacts.