On a whole life of exposure to things that give cognitive decline, apart from that happening naturally with aging (of course with overlap between those two things) the effect is probably not that big, but these last years research has shown that no amount of alcohol is date for brain health. So you probably lost some cognitive function. But thievish probably not that significant against a whole life. And besides brain plasticity (which is mostly activated by using it) makes it so that this is a sort of unanswerable/unmeasurable question.

In short since it is in the past (don’t know how much) and was only a year, and I’m assuming you didn’t go on a weekly blackout drinking session; don’t stress about it too much, that’s not good for cognitive function ;p