There is good and bad cholesterol. They sum it up by saying, what is good for the heart, is good for the brain.
Certain changes in lifestyle can have a positive impact on raising HDL levels:
Aerobic exercise, Weight loss, Smoking cessation.
Removing trans fatty acids from the diet
One to two drinks of alcohol a day - HDL transports cholesterol to the liver and cholesterol is known to have a protective effect on the cell membrane. It is likely that this reflects the liver's need for more cholesterol to protect itself from the alcohol. Adding monounsaturated and polyunsaturated fats to the diet, and reducing or eliminating saturated fats. Adding soluble fiber to diet. Oats are a prime source. Taking Omega 3 fatty acids such as in tuna, or sardines, or suppliments. Limiting intake of dietary fat to 30–35% of total calories
Taking Niacin aka Vitamin B3