George Huguely's guilt or innocence of first-degree murder will likely hinge on his thought process the night Yeardley Love died.  One clinical psychologist says the brains of people in their 20s work differently because they're simply not fully matured.

Dr. Jay works with University of Virginia students everyday.  She treats students one-on-one and teaches clinical psychology.  She just finished a book called "The Defining Decade" that focuses on young people, and how their brains react at this age.

Dr. Jay said, "Unfortunately there's a lot of misinformation out there that tells 20-somethings that real life hasn't started yet."

They may be "off at college," but like high school, they're still going to class.  That could easily give them a false sense of security.

"Oftentimes there's a tendency for young people to minimize dangers and risks.  They can be unrealistically optimistic which is that sense that nothing bad will ever happen to me," stated Dr. Jay.

The death of Yeardley Love poked a huge hole in that idea for a lot of students.  UVA fourth year student Valerie Shuping said, "It felt like a little bit of my safety was threatened because I hadn't thought about anything bad happening."

Dr. Jay says 20-something thoughts like that boil down to youth.  She said, "The frontal lobe is the part of our brain that anticipates the consequences for our actions and helps us balance impulses with impulse control and that's not fully matured until sometime in our mid-20's."

When those immature brains add alcohol to the equation, as witnesses in Huguely's trial say both he and Love did, they can create the perfect storm.

Dr. Jay said, "That's a dangerous combination that can quickly and unpredictably lead to violence and even death."

On the flip side, Dr. Jay says there's good news.   If young people detect problems with alcohol or violence in their lives, now is the time to make changes because it's possible to rewire the still developing brain, and get on the right path in this critical final stage of growth.  Dr. Jay's book "The Defining Decade" comes out in April.