I'm certain that our MrsD is MUCH more knowledgeable about these things and will offer her wisdom shortly. In the meantime, if its ok I'll offer my limited understanding in case it's of any help.

It is believed that free-radicals play a part in nerve damage, thus the pain associated with that damage.

It is also believed that ALA has the capacity to enter our cells (nerve cells in this case) and fight off free-radicals, preventing more from entering and working their destruction.

Therefore, ALA may play a significant part in protecting nerve cells from further damage, and subsequent pain.

Regarding why Lyrica may cause weight gain, it increases appetite, so we are more likely to overheat.