• Depression: Autistic children may complicate into a depressed adolescents once they realize their obvious deficiencies. If an autistic child suddenly begins gaining or losing weight, loses sleep and generally appears more listless than usual, depression may have set in.
• Behavioural problems:

  

  Severely autistic people usually border towards obsession for a certain object / subject. This can transform into a full-fledged Obsessive Compulsive Disorder, wherein the obsessive thought and compulsive action can intrude on the daily routine of the patient.
• ADHD: Autistic children can become hyperactive, easily distracted and show increased difficulty towards concentrating on tasks.

  

  These issues can come from frequent changes in routine and distracting environmental stimuli like sounds and bright colors.
• Anxiety: Autistic children have to cope with different situations and difficulties. This can precipitate varying levels of anxiety and manifest as irritability, temper tantrums or even physically as aches and pains, indigestion or headache.
• Seizures: About one-third of autistic people, especially children and adolescents can suffer from seizures or fits.
• Problems related to sensitivity: Many autistic individuals have been seen to be extremely sensitive to various environmental impressions like heat, cold, sounds and touch. On the other hand, few individuals can show complete insensitivity to such stimuli.
• Mental Retardation: There is some level of mental impairment in autistic children. Some children, however, can complicate into frank mental deficiency.