Hallucinations in children can be a confounding symptom and it is important to evaluate further if a child is presenting with concerns about hallucinations. It is important to distinguish among true hallucinations (false auditory, visual or other sensory perceptions that are not associated with real external stimuli), illusions (misperceptions of actual stimuli), imaginary friends, fantasies and eidetic images (vivid images stored in memory, as may occur in PTSD syndromes). There are many ways in which true hallucinations differ from non- hallucination phenomena. For example imaginary friends can appear and disappear as the child’s wishes, are not scary to the child, and are not ego- dystonic.
It is important to thoroughly assess for other causes for the hallucinations before considering a psychotic disorder because primary psychotic disorders are very rare in children. It is important to conduct a thorough clinical history and physical exam, and to consider basic labs and/or brain imaging if there are other signs of a medical or neurological process. Medical causes for hallucinations include: seizures, brain tumors (particularly in the visual association areas, temporal lobes and area around the optic nerve and retina), thyroid disease, electrolyte imbalances and adrenal disorders.
Medications that can commonly cause hallucinations include steroids, anticholinergics, and stimulants. It is important to consider the possibility of illegal drug use, including marijuana, even in very young children, who may have either taken the drug on purpose or ingested it accidentally. Visual, olfactory and gustatory hallucinations in children may suggest a medication or substance-related cause. It is important to rule out hypnagogic hallucinations, which occur immediately before falling asleep and hypnopompic hallucinations, which occur during the transition from sleep to wakefulness, both of which are normal phenomena.
True hallucinations in children are more likely to be a part of a non-psychotic psychiatric disorder than a primary psychotic disorder. Hallucinations can occur in children with non-psychotic psychiatric disorders, like depression, anxiety, and disruptive disorders. Hallucinations are not uncommon in depression in children but may suggest a higher risk for developing bipolar disorder. It is common for grieving children to hear “voices” from recently deceased loved ones. It’s important to remember that children who have experienced trauma can experience hallucinations as part of the trauma reaction. Hallucinations are common in children with developmental delays, including autism spectrum disorder. Children with language disorders may talk about “voices” because they cannot describe their own thoughts. In these situations, it can be helpful to ask a child if s/he is experiencing the voice inside of outside his/her head.
After ruling out the above, one can consider a primary psychotic disorder. It is important to assess for other psychotic symptoms (like disorganized speech, bizarre behavior, delusions, paranoia) as well as negative symptoms of psychosis (apathy, amotivation, and decline in functioning) before assuming a primary psychotic disorder, because a diagnosis of a primary psychotic disorder should not be made based on hallucinations alone.
In conclusion, while the report of hallucinations in children is worrisome, it is unlikely that it represents a psychotic disorder. It is important to conduct a thorough history to determine the underlying cause of the reported symptom.