Hello! Please remember that my response is for information only, we are not establishing a therapeutic relationship.
I imagine that you and your nephew's parents are extremely concerned about his behavior. You said "silent mutism," but I assume that you meant selective mutism
. Here are the symptoms of selective mutism:
1. The child is consistently unable to speak when it comes to certain social situations, (school,public, etc) however, they are able to speak in other situations (home with just their immediate family).
2. Selective mutism will interfere with the child's educational achievement and social communication. Later on, if left untreated, it will also interfere with their occupational achievement.
3. Symptoms must persist for at least one month (with the exception of the first month of school).
4. The child has difficulty maintaining eye contact.
5. The child is reluctant to smile and oftentimes he will have blank facial expressions.
6. The child's body movements are often stiff and awkward.
7. A child who has this disorder also has a tendency to worry more about things than other people do.
8. Someone who has selective mutism will be extraordinarily sensitive to noise, crowds and crowded situations (including public restrooms).
9. The child will have difficulty with both verbal and non-verbal expression.
10. A child who has selective mutism will oftentimes have frequent temper tantrums at home.
11. Those who are diagnosed with selective mutism oftentimes have compulsive traits that appear to be similar to Obsessive Compulsive Disorder (OCD)--but that does NOT mean that they have OCD.
12. When the person who has selective mutism is still young, he will cling to his parent or other caretaker.
13. A person with selective mutism may appear to be excessively shy when in reality they actually have a fear of people.
14.People with selective mutism may also have an anxiety
disorder such as social phobia
What you describe fits with many of the symptoms above, and I would say that you should trust the diagnosis that he received (although there is no harm in getting a second opinion if his parents need that reassurance).
There is no evidence that it is a hereditary disorder, however, there does seem to be a predisposition to the selective mutism if one or both parents suffer from an anxiety disorder. There is a theory that people with selective mutism have an overactive amygdala, the part of the brain that notices threats and kicks in the "fight of flight" response. The belief is that speaking is a "threat" to these people, therefore, their speech shuts down when they feel threatened.
Treatment: Psychotherapy would be the treatment of choice --and I would go with a child Psychologist who is familiar with anxiety and selective mutism. Cognitive Behavioral Therapy (CBT) would be a good choice. www.mindovermood.com, www.nacbt.org/whatiscbt.htm .
Therapy should focus on helping your nephew understand when his body feels threatened, identify triggers, and learn how to desensitize himself to the threats so that he can speak in spite of feeling anxious. Antidepressants are sometimes used, but I would encourage you to consider medication as a last resort rather than a first choice.
With a good Psychologist, the outlook for recovery is very positive.
I am happy to elaborate on any of these points, feel free to follow up with me. I will work with you until you can give a positive rating!