Yes. There are several studies on essential hypertension. The psychiatric angle has been explored since as early as 1950s. I would not go so far as to say that psychiatric issues are the crux of EH but psychiatric factors do seem to play a vital role in the same, especially in females. A latest study published in european psychiatry should give you a good insight. Please see the link:http://www.europsy-journal.com/article/S0924-9338%2814%2977984-2/abstract