By the time a normally developing child reaches the age of 2 years, his or her has reached half of his or her adult height potential. Especially important, however, is the astounding maturation that occurs in the central nervous system (CNS). This development allows children to acquire several paramount skills, including the development of motor abilities, the maturation of perceptual abilities and pathways, and the acquisition of language.

Children younger than 7 years of age have limited capacities to verbally recount their feelings or interpersonal interactions. For these younger children as well as a number of older ones, play is a useful adjunct to direct questioning and discussion and is often a less challenging mode for children. Some children find it easier to communicate in displacement; thus, imaginative play with puppets, small figures, or dolls can provide the interviewer with useful inferential material about the child’s concerns, perceptions, and characteristic modes of regulating affects and impulses.

The skilled interviewer will facilitate the child’s engagement in play without prematurely introducing speculations or reactions that might distort or cut short the presentation of certain types of material. During the course of play, the clinician follows the sequences of play content, noting themes that emerge, points at which a child backs away from a story or shifts to a new activity, and situations in which the child gets “stuck” or falls into a repetitive loop. To facilitate the play components of an interview, the interview room should have a supply of human and animal figures or dolls and appropriate props. These should be relatively simple because elaborate toys can serve as distractions rather than as vehicles for expression. Stock characters (e.g., Barbie or Disney figures) may impose their own specific story lines and thus limit access to the child’s own concerns.

The content of the child’s play provides important details of the mental status examination. During imaginative play, the clinician observes the child’s coordination and motor skills, speech and language development, attention, ability to relate, capacity for complex thought, and affective state. Absence of imaginative play or limited, concrete, non-interactive play may indicate a pervasive developmental disorder.

More complex games such as chess should be avoided given their demand for concentration, which precludes conversation. Video games likewise tend to serve as an impediment to meaningful interaction.

In children with a first and second language, the language centers appear in the same cortical region, but when a second language is acquired in adult life, the new language center is not represented in the same cortical region as the first language.

A variety of instruments exist for the structured assessment of infants and young children, and each has somewhat different goals, theoretical orientation, and psychometric properties. These instruments do not yield diagnoses but rather detail the child’s developmental progress in various areas relative to a normative population. For example, the Denver Developmental Screening Test (Denver II) is suitable for screening use by pediatricians and trained paraprofessionals to help identify children with significant motor, social, or language delays requiring more complete evaluation. Population-specific norms are also available for assessing children from families of various ethnic or educational backgrounds. The Bayley Scales of Infant Development II, which are administered by a trained assessor, can be used to evaluate children 1 to 42 months of age and include a mental scale (assessing information processing, habituation, memory, language, social skills, and cognitive strategies), a motor scale (assessing gross and fine motor skills), and a Behavior Rating Scale for assessing qualitative aspects of the child’s behavior during the assessment. This well-standardized instrument yields standard scores for a Mental Development Index and Psychomotor Development index.

Although these kinds of tests show good (not fair) reliability and validity, their ability to predict later performance on IQ assessment or later adaptive functioning is highly variable. Among the reasons for this weakness of prediction are the intervening effects of social and family environment and the heavy emphasis infant tests place on perceptual and motor skills that may have relatively little to do with information-processing abilities.

The mental status examination of infants and young children may be organized using a schema such as that shown in Table 36.1.

The clinical utility and cost effectiveness of routine laboratory and imaging studies of children presenting with psychiatric symptoms has not been thoroughly studied. Most guidelines for performing these tests for children derive from data from adult studies. Adult studies generally suggest that routine laboratory tests such as thyroid function tests are not clinically useful in settings such as outpatient psychiatry clinics or most inpatient units. Diagnostic tests are of greater utility in certain psychiatric settings where patients are at higher risk for medical illness, such as emergency departments, substance abuse treatment settings, AIDS clinics, and geriatric clinics.

Additionally, these tests are considered to be worthwhile in patients with first-onset psychosis, depression, mania, or dementia. Furthermore, routine laboratory screening is more likely to yield clinically useful information when signs or symptoms of physical illness are present.

More specialized diagnostic evaluations (CT, MRI, electroencephalography) also appear to provide low yield of clinically useful information. In a study of 200 consecutive child psychiatric inpatients, these evaluations were done only when “clinically indicated.” However, despite their judicious use, the tests provided clinically relevant information in only seven of 200 patients (3.5 percent). In the same sample population, chromosomal analysis proved to be the most informative test, yielding new medical diagnoses in five of 32 children on whom these analyses were performed (15.6 percent). More specialized neuroimaging techniques, such as PET, single photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI), currently have no routine clinical or diagnostic utility in child and adolescent psychiatric populations.