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Biomedical subjects

M V Solanto

Publications and source records attributed to M V Solanto.

At least 19 recordsLinked to original sources
PubMed2001

The ecological validity of delay aversion and response inhibition as measures of impulsivity in AD/HD: a supplement to the NIMH multimodal treatment study of AD/HD.

Impulsivity is a primary symptom of the combined type of Attention Deficit/Hyperactivity Disorder (AD/HD). The Stop Signal Paradigm is premised upon a primary deficit in inhibitory control in AD/HD, whereas the Delay Aversion Hypothesis, by contrast, conceptualizes impulsivity in AD/HD, not as an inability to inhibit a response, but rather as a choice to avoid delay. This study compared the ecological validity of the Stop Signal Task (SST) and Choice-Delay Task (C-DT) measure of delay aversion, with respect to their relative utility in discriminating AD/HD children from normal control participants, and their correlations with classroom observations and with ratings of impulsivity and other core AD/HD symptoms on the Conners and SNAP-IV checklists. The tasks exhibited modest discriminant validity when used individually and excellent discriminant validity when used in combination. The C-DT correlated with teacher ratings of impulsivity, hyperactivity, and conduct problems, and with observations of gross motor activity, physical aggression, and an AD/HD composite score. The SST correlated with the observations only. These results suggest that delay aversion is associated with a broad range of AD/HD characteristics whereas inhibitory failure seems to tap a more discrete dimension of executive control.

Analysis of Variance↗
PubMed2000

Clinical psychopharmacology of AD/HD: implications for animal models.

A working knowledge of the clinical psychopharmacology of the psychostimulants in AD/HD is essential to the development of valid animal models of the disorder. The clinical pharmacokinetics and pharmacodynamics of D-amphetamine (D-AMP) and methylphenidate (MPH) have been well-studied. The plasma half-life of these compounds in children is approximately 5 h, with an onset of therapeutic action within a half-hour, and peak action at 1-3 h. The effective dose range for D-AMP in children is 0.2-0.5 mg/kg, and for MPH 0.3-1.0 mg/kg. In humans, psychostimulants bring about reductions in activity level and impulsivity, and improvement in attention span. Enhancement of executive processes mediated in the pre-frontal cortex in humans (especially tolerance for delay) is believed to mediate these therapeutic effects. There are no long-term remedial effects of the drug on behavior-i.e. symptoms return when the drugs are withdrawn. When used in the therapeutic dose range, there is no evidence of the development of significant tolerance or sensitization. These and other clinical findings to be discussed must guide and constrain the development of animal models of stimulant drug effects in AD/HD.

Attention Deficit Disorder with Hyperactivity↗
PubMed1998

Neuropsychopharmacological mechanisms of stimulant drug action in attention-deficit hyperactivity disorder: a review and integration.

The psychostimulants, D-amphetamine (D-AMP) and methylphenidate (MPH), are widely used to treat attention-deficit hyperactivity disorder (ADHD) in both children and adults. The purpose of this paper is to integrate results of basic and clinical research with stimulants in order to enhance understanding of the neuropharmacological mechanisms of therapeutic action of these drugs. Neurochemical, neurophysiological and neuroimaging studies in animals reveal that the facilitative effects of stimulants on locomotor activity, reinforcement processes, and rate-dependency are mediated by dopaminergic effects at the nucleus accumbens, whereas effects on delayed responding and working memory are mediated by noradrenergic afferents from the locus coeruleus (LC) to prefrontal cortex (PFC). Enhancing effects of the stimulants on attention and stimulus control of behavior are mediated by both dopaminergic and noradrenergic systems. In humans, stimulants appear to exert rate-dependent effects on activity levels, and primarily enhance the motor output, rather than stimulus evaluation stages of information-processing. Similarity of response of individuals with and without ADHD suggests that the stimulants do not target a specific neurobiological deficit in ADHD, but rather exert compensatory effects. Integration of evidence from pre-clinical and clinical research suggests that these effects may involve stimulation of pre-synaptic inhibitory autoreceptors, resulting in reduced activity in dopaminergic and noradrenergic pathways. The implications of these and other hypotheses for further pre-clinical and clinical research are discussed.

Adult↗
PubMed1997

Resumption of menses in anorexia nervosa.

OBJECTIVE: To determine factors associated with resumption of menses (ROM) in adolescents with anorexia nervosa. DESIGN: Cohort study with 2-year follow-up. SETTING: Tertiary care referral center. PATIENTS: Consecutive sample of 100 adolescent girls with anorexia nervosa. INTERVENTIONS: Body weight, percent body fat, and luteinizing hormone, follicle-stimulating hormone, and estradiol levels were measured at baseline and every 3 months until ROM (defined as 2 or more consecutive spontaneous menstrual cycles). Treatment consisted of a combination of medical, nutritional, and psychiatric intervention aimed at weight gain and resolution of psychological conflicts. MAIN OUTCOME MEASURES: Body weight, body composition, and hormonal status at ROM. RESULTS: Menses resumed at a mean (+/-SD) of 9.4 +/- 8.2 months after patients were initially seen and required a weight of 2.05 kg more than the weight at which menses were lost. Mean (+/-SD) percent of standard body weight at ROM was 91.6% +/- 9.1%, and 86% of patients resumed menses within 6 months of achieving this weight. At 1-year follow-up, 47 (68%) of 69 patients had resumed menses and 22 (32%) remained amenorrheic. No significant differences were seen in body weight, body mass index, or percent body fat at follow-up in those who resumed menses by 1 year compared with those who had not. Subjects who remained amenorrheic at 1 year had lower levels of luteinizing hormone (P < .001) and follicle-stimulating hormone (P < .05) at baseline and lower levels of luteinizing hormone (P < .01) and estradiol (P < .001) at follow-up. At follow-up, a serum estradiol level of more than 110 pmol/L (30 pg/mL) was associated with ROM (relative risk, 4.6; 95% confidence interval, 1.9-11.2). CONCLUSIONS: A weight approximately 90% of standard body weight was the average weight at which ROM occurred and is a reasonable treatment goal weight, because 86% of patients who achieved this goal resumed menses within 6 months. Resumption of menses required restoration of hypothalamic-pituitary-ovarian function, which did not depend on the amount of body fat. Serum estradiol levels at follow-up best assess ROM.

Adipose Tissue↗
PubMed1997

Effects of methylphenidate and behavioral contingencies on sustained attention in attention-deficit hyperactivity disorder: a test of the reward dysfunction hypothesis.

Psychostimulants and behavior therapy have been postulated to be effective in treating attention-deficit hyperactivity disorder (ADHD) by compensating for a pathologically elevated reward threshold, but no studies have compared reinforcement to psychostimulants in maintaining task performance. The separate and combined effects of methylphenidate (MPH, 0.6 mg/kg) and a behavioral intervention (reward plus response cost) were assessed on a continuous performance test (CPT, a measure of sustained attention) modified to deliver auditory feedback contingent upon the subject's responses. Each of 22 children (6-10 years old) with ADHD were tested under four treatment conditions: placebo + feedback, placebo + behavioral contingencies, MPH + feedback, and MPH + contingencies. CPT performance, indexed by d' (ability to discriminate between target and false targets), was significantly better with MPH than with placebo, showing reduced deterioration over time. Contingency treatment improved mean d' compared to placebo + feedback but, in contrast, had no effect on the slope of performance deterioration. Addition of contingencies to MPH did not yield further improvement. The results indicate that MPH improved sustained attention on a laboratory task (and reduced task-irrelevant and other disinhibited behaviors), whereas behavioral contingencies did not. These findings suggest that, although both interventions improved stimulus discrimination processes, only MPH enhanced processes that mediate the regulation of effort over time. In addition, the disjunction between the effects of reward and of MPH provides evidence that psychostimulant effects on attention are only partially explained by the stimulation of brain centers associated with reward.

Attention↗
PubMed1995

Usefulness of the Rorschach inkblot test in assessment of attention deficit hyperactivity disorder.

The Rorschach inkblot test is commonly used in the psychological evaluation of children. Yet there is little information about the Rorschach performance of children with Attention Deficit Hyperactivity Disorder (ADHD). The responses of 24 children rigorously diagnosed with ADHD were scored using the Exner system and compared with normative data. Given their greater impulsivity, poor attention span, and increased responsivity to external stimuli, we predicted that, when compared to norms, the ADHD group would have more color dominant responses (CF), a lower FC:CF + C ratio, fewer human movement responses (M), lower sumM:WsumC and sumM + WsumC ratios, poorer form quality (X-%), and would have the same number of or more detail (D) responses. The results yielded support only for those hypotheses concerning M, X-%, and sumM:WsumC. Comparisons between small subgroups with and without ODD suggested differences in the frequency of Human but not Aggressive responses. Possible reasons for the discrepancies from predictions are discussed.

Aggression↗
PubMed1994

Rate of weight gain of inpatients with anorexia nervosa under two behavioral contracts.

OBJECTIVE: To ascertain the rate of weight gain of inpatients with anorexia nervosa under two behavioral contracts, differing in criterion weight gain required to earn increasing privileges. DESIGN: Follow-up comparison of cohorts receiving different interventions. SETTING: Eating disorders service, operating on a general adolescent medicine unit. PATIENTS: Patients admitted consecutively who met the following criteria: (1) weight at least 15% less than that expected for age, sex, and height; (2) female gender; (3) absence of chronic medical illness; (4) hospital stay of at least 28 days. Twenty-two patients meeting these criteria were treated between July 1987 and October 1988, when contract 1 was in effect. This cohort of patients was compared with a group of 31 patients, also meeting the these criteria, who were treated between November 1988 and December 1991, when contract 2 was in effect. INTERVENTIONS: The behavioral contract, signed by the patient on admission, specifies the minimum 4-day weight gain necessary to earn increasing ward privileges, such as use of phone, frequency of visits, etc. Contracts 1 and 2 differed only in the 4-day weight gain criterion: 0.8 lb (0.36 kg) and 1.2 lb (0.55 kg), respectively. RESULTS: The results of analysis of covariance, with admission weight as the covariate, revealed a significant interaction between contract and day, such that patients receiving contract 2 gained weight more rapidly (0.36 lb/d) than those receiving contract 1 (0.20 lb/d). There was no confounding difference between groups in the use of psychotropic medication, and no complications of refeeding in either group. CONCLUSION: Increasing the 4-day criterion weight gain from 0.8 to 1.2 lb in a behavioral contracting intervention was associated with a significant increase in the rate of weight gain, without an accompanying increase in complications of refeeding. This result simultaneously: (a) provides support for the efficacy of behavioral contracting and (b) reveals malleability in the rate of gain based on the targeted gain specified in the contract.

Adolescent↗
PubMed1991

Effects of sugar on aggressive and inattentive behavior in children with attention deficit disorder with hyperactivity and normal children.

Foods high in refined sugar are claimed to exacerbate hyperactivity and increase aggressive behavior. Controlled studies have failed to confirm any effect on hyperactivity and effects on inattention have been equivocal. Possible effect on aggressive behavior has received little study. This study assessed cognitive attention and aggressive behavior immediately following an acute ingestion of sugar compared with saccharin and aspartame-sweetened placebos in 17 subjects with attention deficit disorder with hyperactivity compared with 9 age-matched control subjects. The sugar and placebo challenges were given with a breakfast high in carbohydrate. Although the children with attention deficit disorder with hyperactivity were significantly more aggressive than the control subjects, there were no significant effects of sugar or either placebo on the aggressive behavior of either group. However, inattention, as measured by a continuous performance task, increased only in the attention deficit disorder with hyperactivity group following sugar, but not saccharin or aspartame. This result is of questionable clinical significance inasmuch as aggressive behavior was unchanged. The finding may be due to the combination of the sugar challenge with a high-carbohydrate breakfast. These findings should be replicated and any possible clinical significance should be documented before any dietary recommendations can be made.

Aggression↗
PubMed1990

The effects of reinforcement and response-cost on a delayed response task in children with attention deficit hyperactivity disorder: a research note.

Children with attention deficit hyperactivity disorder are more inattentive, active, and impulsive than normal children. Some researchers have postulated that these symptoms can all be explained as a result of reduced sensitivity to reinforcement. In order to evaluate this hypothesis, we tested 20 ADD-H children and 18 matched normal controls, 4 1/2-11 years of age, on a delayed response task, a measure of impulsiveness, under conditions of positive reinforcement, and punishment in the form of response-cost. The contingencies each improved performance compared to baseline but did not differ significantly from each other. Neither contingency affected the groups differentially, thus failing to provide support for the reinforcement hypothesis.

Attention Deficit Disorder with Hyperactivity↗
PubMed1989

Does methylphenidate constrict cognitive functioning?

It has been suggested that stimulants enhance attention in children with (attention deficit disorder with hyperactivity) (ADDH) by producing a generalized constriction or "over-focusing." Such a phenomenon might be expected to adversely affect performance on tasks, such as those in the Wallach-Kogan (W-K) battery, which explicitly call for cognitive flexibility or "divergent thinking." Nineteen ADDH children, 6 to 10 years of age, were tested on two modified subtests of the W-K battery at baseline, following placebo, and following three different dosages (.3, .6 and 1.0 mg/kg) of methylphenidate. Contrary to the hypothesis, methylphenidate did not decrease but rather sustained output on the tests, which contrasted with a decline in productivity seen across nondrug days. Some ADDH subjects displayed particularly large increases in output following methylphenidate and may represent an atypical subgroup of children who became overaroused on medication.

Arousal↗
PubMed1988

Prevalence of hyperactivity among newly immigrated Chinese-American children.

There has been little research on the prevalence of hyperactivity among Chinese or Chinese-American children. We administered the 28-item Conners Teacher Rating Scale (TRS) to the teachers of recently immigrated Chinese-American children in grades one through six and obtained data on 282 children. The percentages of children scoring above the criterion score for hyperactivity were 8.76% (boys) and 1.72% (girls). These percentages are less than those reported for comparable samples from all other countries, except South Africa. A factor analysis of the TRS data revealed a factor structure that was largely similar to that reported by Conners, but with notable differences between boys and girls. The relative contributions of genetic and cultural factors to the etiology of hyperactivity are considered in a discussion of the prevalence data.

Asian↗
PubMed1985

Electrodermal activity of undersocialized aggressive children: a pilot study.

Electrodermal activity of 11 children with conduct disorder (CD) and 11 normal children were compared during periods of rest, moderate tone and loud bell stimulation. The CD group was best differentiated from controls by lower reactivity to the first bell, while on tonic measures they showed normal values. The electrodermal profile of the CD children thus resembled that of adult sociopaths on phasic measures only. The possibility of using electrodermal measures for predicting outcome and for differential diagnosis is raised.

Acoustic Stimulation↗
PubMed1984

The effect of stimulant medication on academic performance, in the context of multimodal treatment, in attention deficit disorders with hyperactivity: two case reports.

Stimulant medications enhance performance on attentional, memory, and perceptual laboratory tasks and improve behavior in the majority of children with attention deficit disorder with hyperactivity. Most investigators, however, fail to find academic improvement. This report presents two cases in which stimulant medication in the context of multimodal treatment led to considerable gain in academic performance. One case was diagnosed as a combination of attention deficit disorder with hyperactivity and overanxious disorder of childhood. In the other case, disordered conduct was the complicating factor. The necessity of using a multimodal approach in children who suffer from multiple behavioral impairments is emphasized.

Achievement↗