Psychosis presenting in childhood and adolescence has been a controversial topic throughout the history of the field of child psychiatry because of the conundrum of diagnostic clarity. As the necessity of diagnostic accuracy informs treatment as well as prognosis, an important question is whether the various psychoses of childhood are contiguous with the adult forms, or whether the symptoms labeled as psychotic in youth, particularly in prepubertal children, are exactly the same as those seen in adults. Historically, the definition of psychosis in children and adolescents has been particularly vague because of confusion regarding the developmentally appropriate role of imagination and fantasy in children and adolescents with and without psychiatric disorders. Formulations of “childhood psychosis” and psychosis were originally conceptualized as part of the spectrum of the pervasive developmental disorders, but currently, symptoms of psychosis and definitions of psychotic disorders do not differ for children, adolescents, or adults in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, Text Revision (DSM-IV-TR)
The word “psychosis” applies to a state of being (ie, a psychotic state) as well as distinct diagnostic entities. The psychotic symptoms described in DSM-IV-TR include disorganization or gross disturbance of thought form or speech, thought content, or behavior, or extreme negativism. A psychotic symptom, or symptom cluster, is associated with a specific disorder as defined by a certain number of symptoms occurring over a circumscribed duration of time with demonstrated impairment. Hallucinations and delusions are usually thought to establish the diagnosis of psychosis. However, neither of these symptoms are pathonomonic of psychosis, as they can occur in other organic medical or neurological conditions, such as dementias or complications of seizure disorders. Normal children with active fantasy lives can often misperceive their thoughts as actual events and can insist in a firm way that a thought or a dream actually occurred, which would seem to meet the definition of hallucination and delusion.
Schizophrenia is perhaps the best studied of the adult psychiatric disorders. Its symptoms and phenomenology are well established, and there is a comparative wealth of neuroimaging, genetic, and neurocognitive research that informs the understanding of this illness. When the criteria are applied to older adolescents, an age group when first episodes often occur, the diagnosis is often reliable. However, in the younger age group, the issues of developing language and cognition interfere with the dependability of diagnostic accuracy. The adult form of schizophrenia is not a monadic entity, but rather appears to be a collection of etiologically distinct disorders with similar clinical presentations. No consistent or gross neuropathology that identifies the illness.
These issues also apply to bipolar affective disorder (BPAD). The template of symptoms and presentation can apply easily to older adolescents as well as adults, but the situation is less clear in younger children.
Because of variability of symptom presentation, psychotic symptoms that can occur within the spectrum comprising childhood-onset schizophrenia (COS, age of onset (≤12 years), eg, schizophreniform disorder, schizotypal disorder, and schizoaffective disorder, are difficult to distinguish from psychotic and nonpsychotic symptoms related to BPAD and major depressive disorder (MDD). Psychotic symptoms in children and adolescents need to be differentiated from other, intense, repetitive, but nonpsychotic phenomena, such as obsessions related to obsessive-compulsive disorder (OCD), anticipatory anxiety related to non-OCD anxiety disorders, rumination related to depression, perseverative thoughts related to developmental disorders, simple disorganization related to attention-deficit/hyperactivity disorder (ADHD), and overvalued ideas. In addition, language deficits and cognitive deficits related to mental retardation may suggest psychosis in nonpsychotic children. Furthermore, nonspecific symptoms, such as anxiety, distractibility, and irritability, may precede a psychotic break and confuse diagnosis based on course of illness. Psychosis not otherwise specified (PNOS) is intended to classify psychotic symptoms not associated with COS, BPAD, or MDD. Accurate and reliable diagnosis of psychosis during childhood remains elusive, and is indicative of the necessity for more thoughtful study.