Denial is the building block of all addiction: it enables addicts to continue in their addiction without seeking help. Denial isn't actually the addiction itself, but it rears its ugly head whenever we start investigating what we're addicted to and why. And it has a powerful hold on people.
Ignorance is bliss and people suffering from addiction don't want to face the fact that they may have a problem - and it's self-reinforcing which is why we hate facing the prospect that our behavior might be unhealthy. Addicts are often self-medicating to abate feelings of stress, separation, or loss instead of dealing healthfully with their problems. This leads to things like financial infidelity, affairs, drinking, and drugs, which provides a temporary fix - on the surface it's much easier to self-medicate than to seek proper treatment.
When we become addicted to something, we're seeking out that thrill-seeking high. It can come from something as simple as a sugar rush, or as illicit as a sexual affair. When we've found our drug of choice- though the rush may be fleeting - we don't see any reason why we should seek help. When we're addicted, we will crash from this feeling, of course but it's enough to keep us in a cycle of denial, to keep us from getting better. Denial exists because addiction feels so good!
Friends and loved ones will have a hard time convincing an addict that they are in denial. One tactic I suggest to people dealing with an addict is to give them what I call a "brush with death." It's often the only thing that can snap someone out of their denial - they will start missing the people in their life and stop taking them for granted through their own actions. Don't feel sorry for them, stay the course. It often takes a person struggling with denial a while to snap out of it! Unless there is movement or change - remember, it's important not to waver when the person pleads their case. Don't listen to words, look at the movement!
To determine if you're experiencing addiction, and denial, a good first step can be to ask loved ones to be honest with you - they often can identify addictive behavior better than you can! Or give yourself a personal assessment - is there something, someone, a behavior, or activity that is taking priority in my life? By "priority" I don't necessarily mean something you spend a lot of time doing - most of us will spend more time at work, for example, than spending time with our partners. That doesn't necessarily mean you're a workaholic. But If you're breaking agreements because of work, straining relationships, constantly checking emails, or taking work calls you might be! The behaviors, thoughts, and priorities that consume you belie what your addiction might be!
For Dr. Bonnie's advice for dealing with someone in denial, click here: http://youtu.be/nmEShUlejj8 And check out her book, Make Up Don't Break Up, which explores the Brush with Death more extensively.