Who cares. Look forward. The brain is still plastic into old age!

Did it effect you?

Probably a little bit, there is a reason drinking is not medically recommended.

It's unlikely it's the biggest factor in determining your overall intelligence.

That award goes to your social economic status.

So don't sweat it, keep learning and growing and there will always be people dumber than you and there will always be people smarter than you

Impossible to tell. Your brain is how it is, rather than worry about what you cannot change, think about what you want to do and how to do it. If you are experiencing cognitive issues or emotional distress that you think might be a long term effect of your young drinking, talk to a therapist or your doctor about how to address those issues now.

Probably somewhat yeah. How much is a harder question.

Most likely no, it probably had no real effect. Although I also have to ask how old are you now?

I don't know if this helps at all, but ...

It's impossible to meaningfully compare the actual you to an imaginary version of yourself.

The only meaningful thing you can do is reflect on whether, with the resources available to you, you can be better at the things you want to be better at.

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 safe 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