^{Attention Deficit Disorder  For those who have family with attention deficit disorder, I would like for you to know about the best link for a good summary of diagnosis and treatment of this disease (read this and you'll now tips that your doctor probably doesn't know).  The NIH put out this statement which answers all the questions in the best way that they can be answered for now.}

For a clear mind, you need normal thyroid, testosterone, and growth hormone levels.  Both T3 and T4 should be checked to get an accurate picture of total thyroid function.  Also, with thyroid function, upper levels of normal give you less risk of dementia than lower levels of normal.

Estradiol of less than 40 gives you an increased risk of dementia (even if you're a man).  While levels should be kept as low as possible in women to lower risks of breast cancer, levels of 50 to 80 are usually required in women to prevent hot flashes and to prevent accelerated aging of skin (many women on Premarin will have blood levels of 150 to 300 or more)..  

If you need personal advice with your hormone levels, let me know.  Assuming you've optimized the neurotransmitters and hormonal balance of your brain, for better concentration,  would next start with How to Think Like Leonardo... for practical ways to improve  (Leonardo is thought by some to be the most intelligent person who ever walked the planet).  Also, gives helpful advice for inspiring your children.