The vast majority of cases of a child having selective mutism stems from their natural inclination to feel anxious. This can be genetic in a child, meaning that in many cases anxiety is almost hereditary. If you have a parent with consistent bouts of stress, you stand a greater chance of suffering.
The most common selective mutism cases are found in children with extreme anxiety. This can result in tantrums, regular crying, mood swings, problems sleeping, and a consistent and perpetual shyness.
Some studies suggest that a part of the brain, the amygdala, is responsible in part for these episodes. The amygdala sets off a signal in the mind when we are put in a position of fear in a bid to help us protect ourselves from harm. In the mind of a child with selective mutism, though, these fearful situations can include situations where, normally, we would seek joy.
This could include birthday parties, family events, typical daily tasks, and/or attending school. The challenge stems from finding out what causes episodes of fear in each child with selective mutism. In the case where a child also has a speech disorder, a learning disability, and/or a processing disorder, they might feel even more anxious when placed in situations where they are expected to speak.