What are the best ways to increase blood circulation to brain...what type of exercise or Medicine or any thing else?

Not much you can do except avoid high g-force situations... which few people have to concern themselves with.

If you have a medical condition... you need to refer to your physician...

Why are you asking?

I recently suffered from psychotic issue Delirium,dementia and lack of concentration... doing exercise helped me a lot in this.. but it need too much effort

If the exercises worked than do the exercises. If they require too much effort then reduce the amount done and build it up. For example, if they said to do 3 sets of 20 push ups but it was too hard, than do 3 sets of 10 push ups today. Tomorrow do 3 sets of 11 push ups. The next day do 3 sets of 12. So on and so forth. Work it up. If you have something that works then make it work for you.

Get or make an incline board. You lie down on your back and tilt it back so that your feet are higher than your head. You could do the same thing lying down on a seesaw.

Of course if you have clogged arteries to the brain, or a very weak heart, or both, not much is going to get blood to your brain the rest of the day. Once you have medical problems, very few of them can be cured by a doctor giving you a pill or doing surgery - most require work by the patient.