Tatum O’Neal. Britney Spears. Lindsay Lohan. Your dear sweet Aunt Mamie. Why do so many substance abusers keep getting sucked back into their addictions–just when you think they’ve bounced back for good? According to psychologists at the University of Wisconsin, it’s because these folks never deal with the original core substance responsible for their substance abuse–a little substance called anger. In fact, University of Wisconsin psychologists have even gone so far as to label “anger” as the number one trigger for abuse of all drugs and alcohol. And they’ve developed a method–called “Forgiveness Therapy”–to help patients find ways to release the rage that is at the root of their addiction.

Guess what? Their “Forgiveness Therapy Program” is working. Big time.

In one University of Wisconsin study, 14 patients with drug and alcohol dependence were randomly assigned either a twice-weekly forgiveness therapy session or routine drug/alcohol therapy treatment. The participants in forgiveness therapy not only showed significantly more improvement than those who only did routine drug/alcohol treatment, they also experienced less recidivism.

In a way, anger is a boomerang-so much so that we could rename it “boomeranger.” If you’re feeling rage, resentment, and bitterness at specific people–or the universe at large–this rage, resentment, and bitterness will come boomeranging back at you in a variety of forms, including depression, physical illness, and/or the self-inflicted anger of substance abuse.

Carrie Fisher said it well when she said: “Resentment is the poison you swallow hoping the other person will die.”

Hence, it’s essential to learn how to release your hostility in a healthy way on a regular basis–which many people don’t know how to do. Unfortunately, women in particular as a group seem to be especially uncomfortable healthfully feeling and expressing their anger because anger is not deemed a particularly feminine emotion.

I confess that after my sexual assault a few years back, I did not allow myself to honestly feel and express my anger. In fact, I was always surprised when people kept saying to me: “You must be so pissed off at that assaulter.”

As far as I could tell, I didn’t feel angry. I did, however, feel very, very hungry. In particular I had this never–ending hunger for chocolate. So much so, I gained 12 pounds after the assault–which is a lot of weight on my five foot three frame.

I’ve never been into drugs or alcohol. Not even in college. For me, I guess it was more natural to make chocolate my drug of choice. And abuse this drug I surely did. On some days I’d gobble up to four bars.

Often I’d find myself muttering, in a kind of mock-voiceover, “Behind the scenes of the self-help book author . . .” as I peeled off another chocolate wrapper.

Having read this University of Wisconsin report, it’s now quite obvious. My urge to devour chocolate was my way of acting out my anger-raging at myself and my thighs–instead of at my assaulter’s kneecaps. Because I didn’t feel comfortable choosing “fight” as my anger release, I chose “flight”–escaping into a chocolate abuse problem so I didn’t have to feel anger I did not want to feel.

Sure enough, as I became more at peace inside about the ordeal I’d been through, literally forgiving the assaulter in a cathartic letter I wrote but never sent, my urge to devour chocolate eventually vanished. Considering this major correlation between anger and substance abuse, I find it interesting that so many childhood stars have addiction problems.

Where might their rage be springing forth from? Perhaps they’re angry that their childhoods were taken away from them–being forced to live adult lives so prematurely? Or perhaps on a subconscious level they feel taken advantage of by their adult handlers–and as children they’re not able to fully process and express their dark emotions? Or perhaps they’re angry that they can never fully trust the motives for the love they receive from others–and as children they simply want true love-ya-for-yourself love?

Interestingly enough, childhood star Drew Barrymore once had a substance abuse problem, which she’s been long fully recovered from. Nowadays, Drew positively radiates joy and buoyancy–representing further support of U of W’s study results–as Drew’s happy nature seems to be all about forgiveness and letting go of past resentments.

When you take the time to think about the dangers of anger, it becomes more and more clear that holding onto anger is not only the number one trigger behind substance abuse problems, but also almost all of our world’s unhappiness. How much happier and emotionally healthier we’d all be if we cleared away our daily resentments–both large and petty–before they amassed too greatly in our heads and hearts.

– By Karen Salmansohn

“The Dangers of Anger” is an excerpt from the book The Bounce Back Book and has appeared in the Huffington Post. It is reprinted with permission of the author.