Ten year old with:
(a) IQ of 139
(b) able to concentrate well
(c) definitely lagging in emotional development
(d) easily turns nasty and violent when under pressure
(e) other people think he's brutish and he has problems in school.
What could it be?
It is not possible to give you an exact cause of his problems. There are a couple of possible influences, including psycho-social problems in his family, loneliness or problems with friends and many more.
Gifted children are often underachieving due to lack of stimulation at school and at home. But very often they have additional emotional or behavioral problems. Some of them have comorbid adhd and are able to cope this neuropsychiatric "deficit" for a while because they develop ways to cope with distraction, desorganisation and other problems associated with adhd. But the problems of impulse control and behavioral problems remain.
But this can only be identified by a local child psychiatrist and with all information available by teachers, school psychologist, parents and other relevant persons for this child