What can measures of text comprehension tell us about creative text production?

Evidence is accumulating that the level of text comprehension is dependent on the situatedness and sensory richness of a child's mental representation formed during reading. This study investigated whether these factors involved in text comprehension also serve a functional role in writing a narrative. Direct influences of situatedness and sensory richness as well as indirect influences via the number of sensory and situational words on the creativity (i.e., originality/novelty) of a written narrative were examined in 165 primary school children through path analyses. Results showed that sensory richness and situatedness explained 35 % of the variance in creativity scores. Sensory richness influenced the originality/novelty of children's narrative writing directly, whereas situatedness had an indirect influence, through the number of sensory words, but both pathways influenced the outcomes to a comparable extent. Findings suggest that creative writing requires similar representational processes as reading comprehension, which may contribute to the development of instructional methods to help children in creative writing assignments.

OROS-methylphenidate efficacy on specific executive functioning deficits in adults with ADHD: a randomized, placebo-controlled cross-over study.

Attention-deficit/hyperactivity disorder (ADHD) is linked to impaired executive functioning (EF). This is the first study to objectively investigate the effects of a long-acting methylphenidate on neurocognitive test performance of adults with ADHD. Twenty-two adults with ADHD participated in a 6-weeks study examining the effect of osmotic-release oral system methylphenidate (OROS-mph) on continuous performance tests (CPTs; objective measures), and on the self-reported ADHD rating scale (subjective measure) using a randomized, double-blind, placebo-controlled cross-over design. OROS-mph significantly improved reaction time variability (RTV), commission errors (CE) and d-prime (DP) as compared to baseline (Cohen's d>.50), but did not affect hit reaction time (HRT) or omission errors (OE). Compared to placebo, OROS-mph only significantly influenced RTV on one of two CPTs (p<.050). Linear regression analyses showed predictive ability of more beneficial OROS-mph effects in ADHD patients with higher EF severity (RTV: ß=.670, t=2.097, p=.042; omission errors (OE): ß=-.098, t=-4.759, p<.001), and with more severe ADHD symptoms (RTV: F=6.363, p=.019; HRT: F=3.914, p=.061). Side effects rates were substantially but non-significantly greater for OROS-mph compared to placebo (77% vs. 46%, p=.063). OROS-mph effects indicated RTV as the most sensitive parameter for measuring both neuropsychological and behavioral deficits in adults with ADHD. These findings suggest RTV as an endophenotypic parameter for ADHD symptomatology, and propose CPTs as an objective method for monitoring methylphenidate titration.

Associations between sleep characteristics, seasonal depressive symptoms, lifestyle, and ADHD symptoms in adults.

OBJECTIVE: The authors explored associations between ADHD symptoms, seasonal depressive symptoms, lifestyle, and health. METHOD: Adult ADHD patients (n = 202) and controls (n = 189) completed the ASESA questionnaire involving lifestyle, eating pattern, and physical and psychological health, and validated measures on ADHD and sleep. ASESA is the Dutch acronym for inattention, sleep, eating pattern, mood, and general health questionnaire. RESULTS: Indication for delayed sleep phase syndrome (DSPS) was 26% in patients and 2% in controls (p < .001). Patients reported shorter sleep, longer sleep-onset latency, and later midsleep. Shorter (R (2) = .21) and later (R (2) = .27) sleep were associated with hyperactivity, male gender, younger age, and seasonal depressive symptoms. Seasonal depressive symptoms were related to hyperactivity, female gender, unemployment, and late sleep (pseudo R (2) = .28). Higher body mass index (BMI) was associated with shorter sleep in patients (ρ = -.16; p = .04) and controls (ρ = -.17; p = .02). Longer sleep showed lower odds for indication of metabolic syndrome (OR = -0.17; p = .053). CONCLUSION: DSPS is more prevalent in ADHD and needs further investigation to establish treatment to prevent chronic health issues.

Understanding planning ability measured by the Tower of London: an evaluation of its internal structure by latent variable modeling.

The Tower of London (TOL) is a widely used instrument for assessing planning ability. Inhibition and (spatial) working memory are assumed to contribute to performance on the TOL, but findings about the relationship between these cognitive processes are often inconsistent. Moreover, the influence of specific properties of TOL problems on cognitive processes and difficulty level is often not taken into account. Furthermore, it may be expected that several planning strategies can be distinguished that cannot be extracted from the total score. In this study, a factor analysis and a latent class regression analysis were performed to address these issues. The results showed that 4 strategy groups that differed with respect to preplanning time could be distinguished. The effect of problem properties also differed for the 4 groups. Additional analyses showed that the groups differed on average planning performance but that there were no significant differences between inhibition and spatial working memory performance. Finally, it seemed that multiple factors influence performance on the TOL, the most important ones being the score measurements, the problem properties, and strategy use.

To act or not to act, that's the problem: primarily inhibition difficulties in adult ADHD.

Forty-nine carefully diagnosed adults with persistent attention deficit/hyperactivity disorder (ADHD), who had never been medicated for their ADHD, were compared with 49 normal control adults matched for age and gender on a large battery of tests in five domains of executive functioning (inhibition, fluency, planning, working memory, and set shifting) and several other neuropsychological functions to control for nonexecutive test demands. After stringent controls for nonexecutive function demands and IQ, adults with ADHD showed problems in inhibition and set shifting but not in any of the other executive functioning domains tested. We argue that adult ADHD may be mainly a disorder of inhibition.

Delayed circadian rhythm in adults with attention-deficit/hyperactivity disorder and chronic sleep-onset insomnia.

BACKGROUND: Previous studies suggest circadian rhythm disturbances in children with attention-deficit/hyperactivity disorder (ADHD) and sleep-onset insomnia (SOI). We investigate here sleep and rhythms in activity and melatonin in adults with ADHD. METHODS: Sleep logs and actigraphy data were collected during 1 week in 40 adults with ADHD, of whom 31 reported SOI. Salivary melatonin levels were assessed during 1 night. Sleep measures, circadian activity variables, and dim light melatonin onset were compared between groups of ADHD adults with and without SOI and with matched healthy control subjects. RESULTS: Compared with control subjects, both groups of ADHD adults had longer sleep-onset latency and lower sleep efficiency. Adults with ADHD and SOI showed a delayed start and end of their sleep period and a delayed melatonin onset compared with adults with ADHD without SOI (p = .006; p = .023; p = .02) and compared with healthy control subjects (p = .014; p = .019; p = .000). Adults with ADHD and SOI also showed an attenuated 24-hour amplitude in their rest-activity pattern, in contrast to those without SOI, who showed a higher day-to-day stability. CONCLUSIONS: These findings demonstrate diurnal rhythm deviations during everyday life in the majority of adults with ADHD that have SOI and suggest that potential benefits of rhythm-improving measures should be evaluated.

Multicenter analysis of the SLC6A3/DAT1 VNTR haplotype in persistent ADHD suggests differential involvement of the gene in childhood and persistent ADHD.

Attention deficit/hyperactivity disorder (ADHD) is one of the most common neuropsychiatric disorders with a worldwide prevalence around 4-5% in children and 1-4% in adults. Although ADHD is highly heritable and familial risk may contribute most strongly to the persistent form of the disorder, there are few studies on the genetics of ADHD in adults. In this paper, we present the first results of the International Multicentre Persistent ADHD Genetics CollaboraTion (IMpACT) that has been set up with the goal of performing research into the genetics of persistent ADHD. In this study, we carried out a combined analysis as well as a meta-analysis of the association of the SLC6A3/DAT1 gene with persistent ADHD in 1440 patients and 1769 controls from IMpACT and an earlier report. DAT1, encoding the dopamine transporter, is one of the most frequently studied genes in ADHD, though results have been inconsistent. A variable number tandem repeat polymorphism (VNTR) in the 3'-untranslated region (UTR) of the gene and, more recently, a haplotype of this VNTR with another VNTR in intron 8 have been the target of most studies. Although the 10/10 genotype of the 3'-UTR VNTR and the 10-6 haplotype of the two VNTRs are thought to be risk factors for ADHD in children, we found the 9/9 genotype and the 9-6 haplotype associated with persistent ADHD. In conclusion, a differential association of DAT1 with ADHD in children and in adults might help explain the inconsistencies observed in earlier association studies. However, the data might also imply that DAT1 has a modulatory rather than causative role in ADHD.

An exploratory study of the relationship between four candidate genes and neurocognitive performance in adult ADHD.

Since neurocognitive performance is a possible endophenotype for Attention Deficit Hyperactivity Disorder (ADHD) we explored the relationship between four genetic polymorphisms and neurocognitive performance in adults with ADHD. We genotyped a sample of 45 adults with ADHD at four candidate polymorphisms for the disorder (DRD4 48 base pair (bp) repeat, DRD4 120 bp duplicated repeat, SLC6A3 (DAT1) 40 bp variable number of tandem repeats (VNTR), and COMT Val158Met). We then sub-grouped the sample for each polymorphism by genotype or by the presence of the (putative) ADHD risk allele and compared the performance of the subgroups on a large battery of neurocognitive tests. The COMT Val158Met polymorphism was related to differences in IQ and reaction time, both of the DRD4 polymorphisms (48 bp repeat and 120 bp duplication) showed an association with verbal memory skills, and the SLC6A3 40 bp VNTR polymorphism could be linked to differences in inhibition. Interestingly, the presence of the risk alleles in DRD4 and SLC6A3 was related to better cognitive performance. Our findings contribute to an improved understanding of the functional implications of risk genes for ADHD.

Response to methylphenidate in adults with ADHD is associated with a polymorphism in SLC6A3 (DAT1).

In this pharmacogenetic study in adults with ADHD (n = 42), a stratified analysis was performed of the association between response to methylphenidate (MPH), assessed under double-blind conditions, and polymorphisms in the genes encoding the dopamine transporter, SLC6A3 (DAT1), the norepinephrine transporter, SLC6A2 (NET), and the dopamine receptor D4, DRD4. The VNTR polymorphism in the 3' untranslated region of SLC6A3 was significantly associated with an increased likelihood of a response to MPH treatment (OR 3.8; 95% CI 1.0-15.2, and OR 5.4; 95% CI 1.4-21.9, depending on the definition of response) in carriers of a single 10-repeat allele compared to patients with the 10/10 genotype. The polymorphisms in DRD4 and the SLC6A2 were not associated with treatment response. This study supports a role of the SLC6A3 genotype in determining the response to MPH in the treatment of adults with ADHD.

Hyperactive night and day? Actigraphy studies in adult ADHD: a baseline comparison and the effect of methylphenidate.

STUDY OBJECTIVES: To investigate parameters of sleep, activity, and circadian rhythm, as well as the effects of methylphenidate on these variables, in adults with ADHD. DESIGN: 1) Baseline group comparison; 2) Double blind, placebo-controlled, cross-over medication trial. SETTING: Data collection took place during daily lives of participants. PARTICIPANTS: 39 normal controls and 33 adults with ADHD for baseline comparisons; 31 adults with ADHD in medication trial. INTERVENTIONS: Treatment with placebo and methylphenidate during medication trial. MEASUREMENTS AND RESULTS: Actigraphy and sleep log data were collected for 7 consecutive nights and days to obtain baseline values for ADHD and normal controls. Repeated measurements during placebo and methylphenidate treatment were conducted for the ADHD group. Actigraphic sleep estimates showed that ADHD subjects took longer to fall asleep, had lower sleep efficiency, and had shorter within-night periods of uninterrupted sleep. These findings were consistent with subjective complaints. Actigraphic measures of ADHD subjects showed continuously elevated daytime activity levels, resulting in a 24-hour pattern that was more stable and less variable than in controls. Methylphenidate led to a later bedtime, later sleep onset, and reduction in sleep duration. However, number and total duration of nocturnal awakenings decreased, while mean duration of within-night periods of uninterrupted sleep increased, indicating more consolidated sleep. CONCLUSIONS: Our data suggest that sleep problems are inherent in adults with ADHD and that methylphenidate reduced total sleep time but improved sleep quality by consolidating sleep.

Executive functioning in adult ADHD: a meta-analytic review.

BACKGROUND: Several theoretical explanations of ADHD in children have focused on executive functioning as the main explanatory neuropsychological domain for the disorder. In order to establish if these theoretical accounts are supported by research data for adults with ADHD, we compared neuropsychological executive functioning and non-executive functioning between adults with ADHD and normal controls in a meta-analytic design. METHOD: We compared 13 studies that (1) included at least one executive functioning measure, (2) compared the performance of an adult ADHD group with that of an adult normal control group, (3) provided sufficient information for calculation of effect sizes, and (4) used DSM-III-R or DSM-IV criteria to diagnose ADHD. RESULTS: We found medium effect sizes both in executive functioning areas [verbal fluency (d= 0-62), inhibition (d = 0-64 and d = 0.89), and set shifting (d = 0.65)] and in non-executive functioning domains [consistency of response (d = 0.57), word reading (d = 0.60) and color naming (d = 0.62)]. CONCLUSIONS: Neuropsychological difficulties in adult ADHD may not be confined to executive functioning. The field is in urgent need of better-designed executive functioning tests, methodological improvements, and direct comparisons with multiple clinical groups to answer questions of specificity.

Does methylphenidate improve inhibition and other cognitive abilities in adults with childhood-onset ADHD?

We examined the effect of methylphenidate (Mph) on inhibition and several other cognitive abilities in 43 adults with Attention Deficit Hyperactivity Disorder (ADHD) by use of Conners' Continuous Performance Test (CPT) and the Change Task (ChT), an extension of the Stop Signal Test (SST). In a double blind, cross-over, placebo controlled study with Mph, tests were administered during the third week of individually titrated treatment with Mph (maximum dose 1 mg / kg / day) and during the third week of treatment with placebo. We established large medication effects for commission errors, standard error of mean reaction time, and attentiveness on the CPT, as well as moderate medication effects for mean reaction time on the CPT and response re-engagement speed on the ChT. For Stop Signal Reaction Time (SSRT) on the ChT, we also established large effects of Mph, but only in a group of participants who showed slow SSRTs on placebo. Mph indeed ameliorates inhibition, which is the core problem of ADHD, and certain other cognitive abilities in adults with ADHD.