A big part of it has to do with levels of brain-derived neurotrophic factor (BDNF), which helps keep neurons healthy and aids in the formation of new synapses and neurons so it is obviously directly tied to being able to form new memories. Some ways I know how to boost it: exercise, meditation, sleep, pantethine*, DHA, blueberries (and probably other berries) and I'm going to hazard that just generally good micronutrient status supports this.

Protecting the brain is important, much of what I just mentioned and nutrition in general protects the brain. Of course we want to do all of the normal good paleo things to reduce inflammation, oxidative stress, and anything that damages the brain. So make sure glutathione is supported by getting enough sulfur and sulfur-containing amino acids, and utilize anything that will protect the brain from damage. I like astaxanthin as a powerful protector**. Other things that damage the brain are excitotoxins, toxin toxins, and too much of various minerals like iron, manganese, copper, zinc, lead, mercury. It is actually good to get your iron levels checked and make sure they're not too high, but be sure to test first.

So in general I think that a paleo diet and lifestyle is ideal, and that there is merit to taking various supplements to get a boost. Check out Evolutionary Psychiatry if you haven't already http://evolutionarypsychiatry.blogspot.com/ and just try to take care of your brain as best you can. There's more to it than what I mentioned but what tends to keep the brain healthy is what keeps the rest of us healthy.

• http://www.wellnessresources.com/tips/articles/pantethine_boost_your_brain_cardio_health_metabolism_and_detoxification/ This is as close to a hack as I get, I'm more of a slow-and-steady type of person.

**http://www.ncbi.nlm.nih.gov/pubmed/19367117

Most importantly, do whatever it takes to get undisturbed sleep. I used to think I had to have my caffeine to be alert, but when I stopped for a while I could feel that I woke up more alert than I was achieving with the coffee. Getting good physical exercise gives me a higher energy level, while sleeping too much or eating a lot of starch makes me very sluggish.

If you can't change the past, learn from it and close the book. Live into the future you want to have one choice at a time. Oh, and don't be like me and plan your answer while the other person's still talking! It took me forever to learn to listen first, then respond.

I'll second the sleep and exercise, and also add making sure you are getting plenty of omega 3s.

I would like to hear what The Quilt has to say about this.

See about nootropics:

http://paleohacks.com/questions/69563/does-anybody-take-nootropics#axzz1cdBobeDr

Apart from that, you need to stay active, to solve problems, i.e. exercise the brain and do new uncomfortable things.

Exercise and sleep finally.

Honestly, I'm going to say practice. None of this is paleo per se, it's just advice about how to focus. Sorry it's kind of long.

I used to teach grad-level standardized tests on the side, and I'd make my students (a) meditate for 30 seconds before each section; (b) create a ritual; (c) practice like their life depended on it or not do it at all.

The more you half-ass your way through anything, the more your brain becomes habituated to half-assing it, and that's a hard habit to break.

The main point of the meditation and exercise isn't what you'd think (after all, how much Zen do you really achieve in 30 seconds?) but rather as practice in focusing. In 30 seconds, you can get a very good sense of exactly how slowly you can make time pass (a big bonus when you're crunched for time). Understanding the passage of time and learning to temporarily ignore all outside stimuli is key.

I find rituals important, like doing 5 pushups or running around the block (plus the 30 second meditation) right before you launch into any tasks requiring extreme focus. It's physically stimulating, but it also functions like Pavlov's bell. If you do the same thing every time, your brain learns that this ritual means focus time, and so the lag between the ritual and maximum focus shortens with practice until it becomes second nature -- five pushups, 30 seconds with closed eyes, and suddenly the lights are brighter and you're in the zone.

So, I don't know if any of that is helpful or what kind of focus you need to achieve right now, but when I get a new student who despite being smart and together just can't focus, I really treat it like marathon training. Do it every day. Some of us are very used to being focused, for some of us it's a learned skill, but it can certainly be learned.

Last note: I know everyone's all anti "chronic cardio," and I don't love it to death either, but I do find it useful for when I really need to get back into focus mode, because it's boring as hell, which also makes it endurance-training for your brain. It helps train you to power through things that are unpleasant for longer than you want. When this is what I'm going for, I don't listen to music, I don't daydream, I just run and stare at the clock for 30 minutes. I suppose you could also do something else unpleasant for 30 minutes, but I feel like at least here you're getting some exercise (which, like everyone else said, helps make you smart anyway).

Healthy fats and some dietary cholesterol will certainly help you get started. Seafood in the form of fatty fish and shellfish will help you here, as will grassfed beef for the O3 content. Ginseng and gingko won't hurt, though I often see their efficacy disputed.

However...

The thing you really need to do to boost your brainpower is to exercise it. I'd recommend getting a subscription to GAMES magazine, in which most of the pages each issue are devoted to crosswords and logic puzzles. Learn how to do cryptic crosswords. Get a DS and a copy of Brain Age. Play along with Jeopardy. Study chess or go. Learn how to write software if you don't already know; http://www.htdp.org/2003-09-26/Book/ is still a stellar first tutorial. Most importantly, remember that you never stop learning whether you are trying or not. Trust your gut when making decisions because it's the result of searching against everything you have ever learned.

You might want to check out Seth Roberts' blog - he's done some intriguing self-experimentation that seems to suggest that butter improves brain function.

http://blog.sethroberts.net/2011/01/29/the-buttermind-experiment/

Anki is a spaced repetition flashcard program. If you need to memorize things, it can't be beat, unless someone else has a better algorithm. You put in what you want to remember, you review it, and you tell it how easy or hard it was to remember. It decides when to have you review it again; the whole point is to have the flashcard come up right before you'll forget it. In this way, you can maximize the amount of stuff you can remember in whatever amount of time you a lot to reviewing.

Other than that, well I just remembered I can vote on this site, so I'll up vote those who have mention the other stuff I do.

Moderate alcohol has not been mentioned yet...

With Good Reason: An Introduction to Informal Fallacies

DMAE seems to help, as does dark chocolate and coffee. I also use FocusFactor, which takes a while to have an effect. (I've noticed that stopping it's use for more than a week has a negative effect, and starting it back up also has a delayed effect.)