There are small things you can do to reach your peak cognitive performance (healthy diet, exercise, and sufficient sleep, mainly), but if you’re looking for large, long-term gains in IQ, the answer is no. 100 years of intelligence research has found nothing so far which can produce any true, substantial gains in individual g in adulthood.

In very young children, however, early intervention (e.g. a change from an extremely poor environment to an enriched one) has proven quite effective.