The reason so many people are deficient in fatty acids, as noted here, is because the average diet in the U.S. has far too much fats which are found in processed and fast foods. It's all about having a good balance in your daily diet.
What are the Best Supplements for Brain Health? 12 supplements that can improve memory, sharpen skills, help you study and prevent/delay dementia like Alzheimer's. Many have other benefits as well. Worth a read to boost your brain power!