February 2007, Vol. XXIV, No. 2
As a consequence of its premorbid impairments, insidious onset, and relative treatment resistance, childhood-onset schizophrenia (COS) presents clinicians with a number of diagnostic dilemmas and treatment challenges. COS occurs in fewer than 1 in 10,000 children1 and fewer than 1% of patients with schizophrenia receive this diagnosis in childhood.2 The ages and rates at onset are similar in boys and girls.3
Characterized by the onset of psychosis before the age of 13 years, COS is typically preceded by behavioral and cognitive symptoms that overlap with features of autism spectrum disorders, affective and disruptive behavior disorders, and speech and language disorders.1,3 Premorbid and comorbid psychiatric disorders make the diagnosis of COS a challenge and its treatment complicated. Persons with COS appear to have the poorest outcome among those in whom schizophrenia is diagnosed,4,5 so early detection of and intervention for COS may be important to maximize the impact of treatment for children and their families.
Children in whom schizophrenia develops commonly show aberrant social and cognitive development in the very early stages, before the onset of psychosis. Precursors of COS include high rates of soft neurologic signs (minor neurologic abnormalities that are not associated with a specific neurologic disorder), significant delays in language and motor development, and social withdrawal.2Table 1 identifies behavioral precursors of COS and common premorbid childhood psychiatric disorders.
The lack of a well-defined period of normal development in children with COS may obscure the delineation of illness onset, making accurate diagnosis more difficult. Compared with adolescent- and adult-onset schizophrenia, the rates of insidious onset in COS are considerably higher, 71%6 compared with about 61% in adolescent and adult cases.7
Clinical assessment and differential diagnosis
COS is 50 times less likely to occur than adolescent-onset schizophrenia.2 The diagnosis of COS requires the presence of persistent hallucinations or delusions, disorganized speech and behavior (positive symptoms), and/or lack of developmentally appropriate affect and goal-directed behaviors (negative symptoms) for at least 1 month, and enduring impairment for at least 6 months. The current criteria in DSM-IV-TR for the diagnosis of COS are identical to those for a diagnosis of schizophrenia in adults with only one modification, namely, a child's failure to achieve an expected level of interpersonal, academic, or occupational achievement, which may replace a deterioration in function. There is no minimum age requirement for COS, and therefore, it can be diagnosed in very young children who meet the above criteria. However, it is rarely diagnosed before preschool age.
Optimal strategies for assessing and diagnosing COS include a structured or semistructured interview with the child and parent, in addition to a clinical interview and observation. A well-accepted semistructured interview is the Schedule for Affective Disorders and Schizophrenia–Present and Lifetime Versions.8
Because of the frequent preexisting thought and language dysfunction, COS is often more challenging to diagnose than schizophrenia in adolescents. For example, delusions or hallucinations may not be easily distinguished from the odd and idiosyncratic thinking in developmental disorders. In addition, a child's report of auditory hallucinations is frequently not pathognomonic of schizophrenia, since most children who report hallucinations do not have schizophrenia and many do not have psychotic disorders9—these hallucinations may simply be hypnagogic or hypnopompic.
Delusions in childhood exceed exaggerated magic beliefs, and these “fixed false beliefs” are often frightening and may drive a child to take an irrational action in an attempt to counteract them. For example, a child with a delusion that a sibling has AIDS and is trying to infect him or her might seek to “protect” himself or herself by wearing boots in the shower and hiding from the sibling at home. Similar counteractive protective behaviors may be observed in children with obsessive-compulsive disorder; however, delusions are often more bizarre than obsessions, and in general, delusional children do not believe that the danger diminishes as a result of their own responses (ie, compulsive rituals do not neutralize the fears).
True psychotic symptoms must be differentiated from children's reports of psychotic-like phenomena surrounding the idiosyncratic thinking and perceptions associated with pervasive developmental disorders (PDD), psychotic-like symptoms that may arise in children with posttraumatic stress syndrome, or anxiety-related transient “phobic” hallucinations. Psychotic symptoms in adolescents, compared with those of young children, are often more clearly described because of the increased developmental abilities of teens to articulate their inner experiences, which helps make the diagnosis of schizophrenia more clear-cut.
The comorbidity and overlap between PDD and COS sometimes makes these 2 disorders difficult to distinguish. Children with PDD may have more idiosyncratic, poorly formulated, peculiar thoughts that may shift or evolve over time. Like children with COS, children with PDD may also have odd beliefs—for example, that they are able to communicate with valued inanimate objects. Phobic hallucinations usually occur in the context of anxiety, such as a child “seeing” a frightening face in the window when it is dark, but which may not trouble the child during the day when the anxiety is muted.
Children with COS often fail to acquire the necessary social skills to fit in with same-age peers and frequently end up isolated. Significant rejection from peers, isolation from sports and other social activities, and generalized confusion and fear may emerge and permeate daily life.