help explain why people with one anxiety disorder are likely to develop a second one—that is, some risk factors increase the odds of having more than one anxiety disorder. For example, the factors that increase risk for social anxiety disorder may also increase risk for panic disorder. Unlike the way we have organized most of the other chapters in this book, we have chosen to begin with the behavioral model. We do this because classical conditioning of a fear response is at the heart of many anxiety disorders. Many of the other risk factors, including genes, neurobiological risk factors, personality
traits, and cognition, can influence how readily a person can be conditioned to develop a new fear response. Taken together, the risk factors combine to create an increased sensitivity to threat (Craske, Rauch, Uisano, et al., 2009). Table 6.5 summarizes the general risk factors for anxiety disorders. Table 6.5 Factors That Increase Risk for More than One Anxiety Disorder Behavioral conditioning (classical and operant conditioning) Genetic vulnerability Increased activity in the fear circuit of the brain Decreased functioning of GABA and serotonin; increased norepinephrine activity Behavioral inhibition Neuroticism Cognitive factors, including sustained negative beliefs, perceived lack of control, and attention to cues of threat Fear Conditioning Above, we mentioned that most anxiety disorders involve fears that are more frequent or intense than what most people experience. Where do these fears come from? Behavioral theory of anxiety disorders focuses on conditioning. Mowrer’s two-factor model of anxiety disorders, published in 1947, continues to influence thinking in this area (see Figure 6.2). Mowrer’s model suggests two steps in the development of an anxiety disorder (Mowrer, 1947): 1. Through classical conditioning , a person learns to fear a neutral stimulus (the CS) that is paired with an intrinsically aversive stimulus (the UCS). 2. Through operant conditioning , a person gains relief by avoiding the CS. This avoidant response is maintained because it is reinforcing (it reduces fear). Consider an example. Imagine that a man is bitten by a dog and then develops a phobia of dogs. Through classical conditioning, he has learned to associate dogs (the CS) with painful bites (the UCS). This corresponds to step 1 above. In step 2, the man reduces his fear by avoiding dogs as much as possible; the avoidant behavior is reinforced by the reduction in fear. This second step explains why the phobia isn’t extinguished. With repeated exposure to dogs that don’t bite, the man would have lost his fear of dogs, but by avoiding dogs, the man gets little or no such exposure. We should note that Mowrer’s early version of the two-factor model does not actually fit the evidence very well; several extensions of this model, which we look at next, have been developed that fit the evidence better (Mineka & Zinbarg, 1998). One extension of the model has been to consider different ways in which classical conditioning could occur (Rachman, 1977). These include the following:
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