C
linically relevant aggression and oppositionality are common treatment targets in child and adolescent psychiatry (Pappadopulos et al.
2003; Schur et al.
2003; Olfson et al.
2006; Pappadopulos et al.
2006; Jensen et al.
2007). Disruptive behavior disorders that are frequently associated with relevant aggression and oppositionality occur in approximately 7–11% of the pediatric population (Loeber et al.
2000; Nock et al.
2007), with an estimated 75% referral rate to psychiatric care among children with these diagnoses (Arcelus and Vostanis
2003). Children suffering from these disorders and symptoms have problems functioning in families, in school, and with their peers. They are also at risk for long-term interpersonal and academic difficulty, legal problems, substance abuse or dependence, and frequent use of social and mental health services (Loeber et al.
2000; Ezpeleta et al.
2001; Nock et al.
2007).
Although they are still somewhat controversial regarding the appropriate timing and sequencing with nonpharmacologic management strategies, pharmacologic treatments, and, in particular, antipsychotics have shown to be efficacious for the symptoms of aggression and externalizing disorders (Pappadopulos et al.
2003; Schur et al.
2003; Pappadopulos et al.
2006; Jensen et al.
2007). There is evidence that antipsychotics can facilitate short-term reduction in symptoms of maladaptive aggression, and risperidone has been shown to be more efficacious than placebo in double-blind, controlled studies (Jensen et al.
2007), with greater effect sizes than for other medication classes, such as mood stabilizers, stimulants, antidepressants and α2 agonists (Pappadopulos et al.
2006).
However, treatment with antipsychotics, and especially with second-generation antipsychotics (SGAs), is complicated by adverse effects, which commonly include weight gain and sedation (Correll et al.
2006; Correll and Carlson
2006; Correll
2008a), two critical issues for children's health and academic and social functioning (Jensen et al.
2007). In addition, SGA treatment has also been associated with varying degrees of metabolic abnormalities (Correll and Carslon
2006; Correll
2008b), prolactin abnormalities (Correll and Carlson
2006; Correll
2008a), and extrapyramidal symptoms (though less so than with first-generation drugs) (Correll et al.
2006). Some of these adverse effects may be particularly problematic early in treatment and then abate (Findling et al.
2003; Haas et al.
2008), but age-inappropriate weight gain and related increases in lipid and glucose parameters are of concern even if they plateau, because they are continuous risk factors that have a close relationship to future cardiovascular morbidity and mortality (Correll
2008a; Correll
2008c).
There are surprisingly few studies investigating interactions between antipsychotics and stimulants in youth, although such a combination is commonly used due to the relatively high prevalence of attention-deficit/hyperactivity disorder (ADHD) in disorders that are frequently treated with antipsychotic medications. This situation is most prevalent in disruptive behavior disorders with significant and impairing levels of aggression (August et al.
1996; The MTA Cooperative Group
1999). Some of the few studies reporting stimulant–antipsychotic co-treatment effects did not find that stimulants reduced side effects when combined with antipsychotics. One such study pooled data from two placebo-controlled, 8-week trials (Aman et al.
2002; Snyder et al.
2002) of risperidone in 155 children aged 5–12 years with disruptive behaviors and subaverage intelligence, and compared, in a
post hoc analysis, those children who had risperidone added to ongoing stimulant treatment (47.1%) to children taking risperidone alone (52.9%) (Aman et al.
2004). In this study, 91% of patients in the stimulant co-treated group, as well as in the nonstimulant group, reported at least one side effect. Moreover, there were no significant between-group differences in weight gain (2.2

kg vs. 2.1

kg,
p
=

0.42) or body mass index (BMI) change (1.2 vs. 1.1,
p
=

not significant [N.S.]), although there was a significant increase in body weight and BMI with risperidone compared to baseline (
p
<

0.001). Furthermore, although fewer patients on stimulants reported somnolence (37.1% vs. 51.2%,
p
=

0.26), this difference was also not significant. Similarly, efficacy regarding behavioral and ADHD symptoms was also not different depending on stimulant co-treatment, with significant superiority of risperidone versus placebo (Aman et al.
2004).
In a related, open-label extension study, 77 completers from the two short-term studies noted above (Aman et al.
2002; Snyder et al.
2002) were followed on risperidone for up to 1 year (Turgay et al.
2002). All but 1 of those youths (98.7%) experienced at least one adverse event, with somnolence remaining the most common (51.9%), followed by headache (37.7%) and weight gain (36.4%). However, the sedation was reported not to have been significant enough to impact cognitive function or efficacy measures. In another study, Calarge et al. (
2009), studied 99 children treated with risperidone for a mean of almost 3 years, also finding no difference in BMI
z-scores measures between children treated with risperidone plus stimulant (
n
=

38) and those treated with risperidone alone (
n
=

61) after controlling for baseline BMI
z-score.
On the other hand, a second line of studies provided preliminary, albeit only indirect, evidence of a potentially attenuating effect of stimulant co-treatment on expected side effects of antipsychotics when added to stimulants. For example, in 24 adolescents, 9 weeks of open-label treatment with quetiapine added to methylphenidate (MPH) after 3 weeks of ineffective stimulant monotherapy resulted in only negligible changes in BMI and weight over the total 13-week study duration (i.e., initial decreases were offset by increases that occurred after quetiapine addition) (Kronenberger et al.
2007). By contrast, sedation increased after quetiapine was added from 17% to 50%, with 2 patients discontinuing after quetiapine addition due to excessive fatigue. Because no control group of quetiapine monotherapy was included, it is not possible to determine whether an otherwise significant weight gain effect could have been mitigated by stimulant co-treatment, but sedation rates were clinically relevant, despite stimulant co-treatment.
Likewise, in a 4-week, double-blind study of 25 children with ADHD who were taking a constant dose of stimulant medication before being randomized to augmentation with risperidone or placebo to reduce treatment-resistant aggression, no significant differences between patients treated with risperidone plus stimulant and those treated with placebo plus stimulants were noted for weight gain (0.9

kg vs. - 0.6

kg) or for sedation (16.7% vs. 23.1%) (Armenteros et al.
2007). This suggests a possible attenuation of the risperidone effect on weight and sedation by stimulant co-treatment, because neither weight gain nor sedation were greater with risperidone than with placebo. Nevertheless, similar to Kronenberger et al. (
2007), no monotherapy group of risperidone treatment without stimulant co-treatment was available for direct comparison, and sample sizes were small in both of these studies.
Furthermore, two case reports in adults describe the amelioration of clozapine-induced sedation with addition of MPH (Burke and Sebastian,
1993), although a third case resulted in worsening of a movement disorder and tolerance to the decrease in sedation initially brought on by the MPH (Miller
1996). Three other cases mentioned the successful management of neuroleptic-induced sedation with modafinil, without worsening of psychotic symptoms (Makela et al.
2003), although another study did not find a greater reduction in fatigue compared to placebo (Sevy et al.
2005).
To our knowledge, no studies are available that have assessed whether stimulant co-treatment with antipsychotics affects metabolic parameters that have been shown to worsen, or prolactin levels that have been shown to increase, with many of the commonly used antipsychotic medications (Correll and Carlson
2006). At least theoretically, potential benefits associated with stimulant co-treatment could be expected for metabolic parameters, either indirectly via attenuation of weight gain or directly via currently unknown mechanisms. Furthermore, a reduction in prolactin levels or attenuation of prolactin elevation associated with certain antipsychotics could be expected due to pro-dopaminergic effects of stimulant medications in the tuberoinfundibular pathway, as seen with full and even partial dopamine agonists when added to dopamine antagonists (Correll and Carlson
2006).
Given the paucity and contradictory nature of the available data, the increasing use of antipsychotics in youth (Olfson et al.
2006), and the clinical relevance of these antipsychotic adverse effects during development, we aimed to examine whether a combination of SGAs with stimulant treatment would result in a statistically significant attenuation of commonly occurring adverse effects of SGAs on body weight, metabolic parameters, prolactin levels, and alertness.