Dumbledore and the poison(?) potion

[ar_hp03]

No: HPFGUIDX 133488

I was just discussing Dumbledore's reaction after drinking the potion
at the cave with a friend and it suddenly struck me that his reactions
seem to be something similar to what we see when people face
dementors, ie., being forced to re-live their worst memories. In the
book it appears that Dumbledore is somehow being forced to re-live his
worst memories.  He speaks about being responsible for something and
begs someone not to kill the others(sorry, don't have the book handy).
IMHO, this closly resembles the way other wizards including Harry
react to demetor attacks. 

If the potion was merely poisonous then the reactions would have been
closer to the way Ron was described at Slughorn's office after driking
the mead. 

What does everyone else think ?

AR, who knows for sure that the potion was a dark potion and was not
poison.