Can Terpenes Increase the Effects of Other Cannabinoids Including THC?

Yes, for example, the terpene Myrcene lowers the resistance across the blood to brain barrier, allowing itself and many other chemicals to cross the barrier easier and more quickly. In the case of cannabinoids (like THC), myrcene allows the effects of the cannabinoid to take effect more quickly. More uniquely still, myrcene has been shown to increase the maximum saturation level of the CB1 receptor, allowing for a greater maximum psychoactive effect.  This is true for foods containing Myrcene as well.  For example, mangos are very rich in myrcene.  Many believe eating a fresh mango about 45 minutes before consuming cannabis will result in a faster and more powerful onset of THC.  The terpenes in mango will, in fact, enhance the intoxicating effects of THC for some, but only if the mango is ripe, otherwise the myrcene level will be too low to make a difference.