Are personality changes common after a head injury with concussion?

Yes: Yes it depends on area of brain affected.

Yes, not permanent: Concussions are a traumatic brain injury (tbi) commonly affecting 4 areas: thinking, emotion, sleep and body. Symptoms affecting thinking are poor concentration, slow thinking; emotional are irritability, sadness, anxious ; sleep are increased sleeping, trouble falling or staying asleep; body are headache, nausea, dizzy, sensitivity to light or sounds. If you have any of these see your doctor.

Not uncommon.: Post-concussion syndrome includes symptoms such as depression, anxiety and irritability.