Cognitive behaviour therapy (CBT) is a common treatment for anxiety disorders. The basic idea of CBT is to change the fear-eliciting thoughts that underlie a client’s anxiety.
Imagine the instance where a person has a dog phobia. They are likely to believe that “all dogs are dangerous”. During CBT, the client is gradually exposed to friendly dogs to cognitively reframe their thoughts or memories into something more realistic – such as the belief “most dogs are friendly”.
CBT is one of the most scientifically supported treatments for anxiety disorders. But unfortunately, a recent US study indicates that in around 50% of patients, old fear memories resurface four years after CBT or drug treatment. Put another way, the old fear memories seem impermeable to erasure through gold-standard therapy or drug treatment.
Why distressing memories are difficult to ‘erase’
Fear memories are stored in an old part of the brain called the amygdala. The amygdala developed early in our evolutionary history because having a healthy dose of fear keeps us safe from dangerous situations that might reduce our chances of survival.
Permanent storage of dangerous information is adaptive. While we might learn some things are safe sometimes (encountering a lion in a zoo) we also need to be aware they not safe in many other circumstances (meeting a lion in the wild).