Susan T. Schwartz

Developmental analysis of three aspects of information processing: Sustained attention, selective attention, and response organization

The development of cognitive abilities associated with Lunas (1973) three functional units of the brain was investigated in a sample of 62 children, ages 7 to 11 years, and 16 adults, ages 21 to 48 years. Selective attention, associated primarily with Lurias sensory‐input unit, showed no demonstrable development within the age ranges studied. However, sustained attention, presumably mediated through Lurias arousal unit and its ascending fibers to the cortex, as well as response organization, associated with Lunas organization‐and‐ planning unit, did reflect differential development Capacity for sustained attention showed no appreciable development between 7 and 11 years of age, but there was significant growth in this ability between age 11 and adulthood. Response organization, on the other hand, was found to develop most rapidly between 7 and 11 years of age. These findings are partially consistent with Lurias model of neurodevelopment as well as with research investigating the functional and physio...

Age-related changes in the association between serotonergic function and aggression in boys with ADHD.

The results of several studies have indicated an inverse relationship between central serotonergic (5-HT) mechanisms and aggression in animals and adults, but studies in children have yielded conflicting results. This study assessed 5-HT function, using a fenfluramine (FEN) challenge procedure, in an attempt to replicate a previously reported enhancement of the prolactin (PRL) response to FEN in aggressive relative to nonaggressive ADHD boys. The study failed to replicate the previous finding. Samples from both studies were then examined to reconcile the discrepant findings. The samples differed significantly in age. The entire group (n = 50) was then divided into older and younger subgroups and reanalyzed using a two-way (age-group x aggression) analysis of covariance (ANCOVA) controlling for plasma medication level. The ANCOVA generated a significant age-group x aggression interaction. Young aggressive boys had a significantly greater PRL response to FEN than young nonaggressive boys, but no such difference existed in the older age-group. These findings raise the possibility of different developmental trajectories in 5-HT function between aggressive and nonaggressive boys.

Discriminant Validity of Attention-Deficit Hyperactivity Disorder

OBJECTIVE The primary purpose of this study was to assess the discriminant validity of attention-deficit hyperactivity disorder (ADHD) relative to well-defined groups of children with other psychiatric disorders. METHOD Clinic-referred patients diagnosed as having ADHD without any other comorbid diagnosis (N = 13), were compared with patients with only anxiety disorders (N = 20), disruptive disorders other than ADHD (N = 15), and nonreferred controls (N = 18) on measures of cognitive and academic functioning, as well as on objective measures of attention, impulse control, and activity level. RESULTS All three patient groups were found to have cognitive and academic achievement difficulties relative to controls. However, the ADHD group was found to be inattentive and impulsive relative to the other patient groups and the nonreferred controls. Objective measurement of activity level distinguished the ADHD group from controls but not from the other two patient groups. CONCLUSIONS These data support the diagnostic validity of a small subgroup of ADHD children (i.e., those without comorbid diagnoses) and demonstrates, that as a group, these children can be distinguished from patients with anxiety as well as other disruptive disorders on objective test measures.

Serotonin, Aggression, and Parental Psychopathology in Children With Attention-Deficit Hyperactivity Disorder

OBJECTIVE To explore the relationship between central serotonergic (5-HT) function and history of parental aggression in aggressive and nonaggressive boys with attention-deficit hyperactivity disorder (ADHD). METHOD History of psychiatric symptoms was assessed in the biological parents of 41 boys with ADHD. The relationship between 5-HT function in aggressive and nonaggressive probands, as assessed via the prolactin response to fenfluramine (FEN) challenge, and parental history of aggression was examined. RESULTS Aggressive boys with a parental history of aggressive behavior had a significantly lower prolactin response to FEN challenge than aggressive boys without a parental history of aggression. Nonaggressive boys had a prolactin response midway between those of the two aggressive subgroups, and their prolactin response did not vary as a function of parental aggression. Children subdivided on the basis of parental history of other psychiatric symptoms did not differ in their response to the FEN challenge. CONCLUSIONS These data indicate an association between parent aggressive behavior and lower 5-HT function in aggressive boys with ADHD but do not indicate the extent to which this association is environmentally and/or genetically transmitted. There may be different neurochemical mechanisms in familial and nonfamilial aggressive children, which have clinical implications for pharmacological interventions.

Inattentive and noninattentive ADHD children: do they constitute a unitary group?

Teacher-rated ADHD and normal control children were administered a continuous performance test (CPT), and were then further subdivided based upon the presence or absence of objectively assessed attentional deficits. In addition, children were assessed using several measures of cognitive and behavioral functioning. Attentional deficits were signficantly more prevalent among the ADHD group, but about half of the ADHD children showed no evidence of objectively assessed attentional dysfunction. Further group analyses indicated that ADHD children with objectively assessed attentional dysfunction appeared cognitively impaired, while ADHD children without objective evidence of attentional dysfunction had more conduct problems. CPT inattention was not related to the presence of cognitive impairments or conduct problems in the control group. These data must be considered preliminary because teacher ratings were the only source of diagnosis and a single measure of inattention was used. However, they suggest that two subtypes of ADHD children can be identified, one characterized by inattention and learning problems, and the other by conduct problems.

Parent and teacher ratings of attention-deficit hyperactivity disorder symptoms: implications for case identification

This study was designed to evaluate the relationship between the DSM-III criteria for attention-deficit disorder with hyperactivity (ADDH) and the DSM-III-R criteria for attention-deficit hyperactivity disorder (ADHD). Seventy-two children from an inner-city elementary school were evaluated using parent and teacher ratings on a scale consisting of the symptoms of DSM-III-R ADHD and oppositional-defiant disorder and DSM-III ADDH. Each child was also assessed using a psychometric test battery designed to examine cognitive function, attention, and activity level. Teacher ratings identified more children as DSM-III-R ADHD than DSM-III ADDH. Among these ADHD children, those who also met the ADDH criteria missed more targets on a continuous performance test (CPT) and were rated more overactive than controls. They also had a greater likelihood of being rated ADHD by parents. Children rated as meeting criteria for DSM-III-R ADHD, but not DSM-III ADDH, were not substantially different from controls on teacher ratings of overactivity, CPT performance, or parent ratings of ADHD, which raises questions regarding the nature and severity of the pathology in this group. J Dev Behav Pediatr 15:86–91, 1994. Index terms: diagnosis, DSM-III-R, attention-deficit disorder.

A longitudinal study of neurobiological mechanisms in boys with attention-deficit hyperactivity disorder: preliminary findings

BACKGROUND The stability and developmental variation of several neurobiological measures in boys with attention-deficit hyperactivity disorder (ADHD) were examined. METHODS The prolactin (PRL) response to fenfluramine (FEN) challenge was used to assess central serotonergic (5-HT) functioning in 10 8-11-year-old boys with ADHD. In addition, platelet 5-HT, as well as plasma levels of the catecholamine metabolites 3-methoxy-4-hydroxyphenylglycol (MHPG) and homovanillic acid were ascertained. These neurobiological variables were reassessed in the same children 2-3 years later using the identical procedures. RESULTS The PRL response to FEN challenge was the only measure found to be stable across the evaluations (r = .58), although the magnitude of the response decreased significantly with age. Plasma MHPG level significantly increased with age. CONCLUSIONS Central 5-HT function, as measured by the PRL response to FEN, may represent a stable trait. The importance of considering developmental factors when interpreting neurobiological data is discussed.

Changes in plasma prolactin and catecholamine metabolite levels following acute needle stick in children

Changes in plasma levels of prolactin (PRL), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) following insertion of an indwelling catheter into a forearm vein were assessed in 11 boys with attention-deficit hyperactivity disorder. Results indicated decreases in plasma PRL and HVA, but not MHPG, from the time of needle stick until 105 min post-insertion. These data indicate a significant increase in plasma PRL and HVA in children following needle stick which gradually decreases over a 1.5-2-h period. These stress-induced changes indicate that values obtained immediately after needle insertion cannot be assumed to accurately reflect baseline levels.