Sleep disturbance and neuropsychological function in young children with ADHD

Sleep disturbance, common among children with ADHD, can contribute to cognitive and behavioral dysfunction. It is therefore challenging to determine whether neurobehavioral dysfunction should be attributed to ADHD symptoms, sleep disturbance, or both. The present study examined parent-reported sleep problems (Children’s Sleep Habits Questionnaire) and their relationship to neuropsychological function in 64 children, aged 4–7 years, with and without ADHD. Compared to typically developing controls, children with ADHD were reported by parents to have significantly greater sleep disturbance—including sleep onset delay, sleep anxiety, night awakenings, and daytime sleepiness—(all p ≤ .01), and significantly poorer performance on tasks of attention, executive control, processing speed, and working memory (all p < .01). Within the ADHD group, total parent-reported sleep disturbance was significantly associated with deficits in attention and executive control skills (all p ≤ .01); however, significant group differences (relative to controls) on these measures remained (p < .01) even after controlling for total sleep disturbance. While sleep problems are common among young children with ADHD, these findings suggest that inattention and executive dysfunction appear to be attributable to symptoms of ADHD rather than to sleep disturbance. The relationships among sleep, ADHD symptoms, and neurobehavioral function in older children may show different patterns as a function of the chronicity of disordered sleep.     

Possible participation of D3 and D4 dopaminergic receptors on genital reflexes induced by cocaine in paradoxical sleep deprived male rats

Previous studies have demonstrated that paradoxical sleep deprivation (PSD) potentiates cocaine-induced genital reflexes in male rats and both D1 and D2 receptors may play a role in those effects, and to examine the possibility that such might involve other dopaminergic receptors, we investigated the effects of D3 and D4 receptor subtype antagonists on cocaine-induced reflexes in sleep-deprived rats. Separate groups of PSD rats received saline, D3 (U9919A; 0.75, 1.5 and 3 mg/kg) or D4 (L745870; 0.75, 1.5 and 3 mg/kg) antagonists prior to acute cocaine challenge. Results demonstrated that U9919A induced significant reduction in the number of animals that displayed erection and the frequency of erection at two smaller doses, while no significant difference was reported for the D4 receptor antagonist. Although our studies indicate that there is a relevant participation of D3 receptors in male sexual function, D4 receptors seem not to exert an essential role in this model.     

The impact of post-learning sleep vs. wakefulness on recognition memory for faces with different facial expressions

A beneficial effect of sleep after learning, compared to wakefulness, on memory formation has been shown in many studies using a variety of tasks. However, none of these studies has specifically addressed recognition memory for faces so far. The recognition of familiar faces, together with the extraction of emotional information from facial expression, is a fundamental cognitive skill in human everyday life, for which specific neural systems and mechanisms of processing have been developed. Here, we investigated the role of post-learning sleep for later recognition memory for neutral, happy, and angry faces. Twelve healthy subjects, after judging the emotional valence of the faces in the evening (learning phase), either slept normally in the subsequent night, with sleep recorded polysomnographically (sleep condition), or remained awake (wake condition) according to a cross-over design. Recognition testing took place in the second evening after learning, i.e. after a further night of regular sleep spent at home. Sleep after learning, compared to wakefulness, enhanced memory accuracy in recognition memory. This effect was independent of the emotional valence of facial expression. The response criterion at recognition testing did not differ between sleep and wake conditions. The amount of non rapid eye movement (NonREM) sleep during post-learning sleep correlated positively with memory accuracy at recognition testing, while time in REM sleep was associated with a speeded responding to the learned faces. Results suggest that face recognition, despite its dependence on specialized brain systems, nevertheless relies on the general neural mechanisms of sleep-associated memory consolidation.     

MTHFR and ACE gene polymorphisms and risk of vascular and degenerative dementias in the elderly

Focal lacunar infarctions due to cerebral small vessel atherosclerosis or single/multiple large cortical infarcts lead to vascular dementia, and different genes and environmental factors have been implicated in causation or aggravation of the disease. Previous reports suggest that some of the risk factors may be common to both vascular as well as degenerative dementia. Among genetic factors, role of angiotensin converting enzyme (ACE) and methylene-tetrahydrofolate reductase (MTHFR) genes as putative risk factors has been examined but the outcome of these studies remain inconclusive. Present study attempted to see the importance of ACE alu insertion/deletion and MTHFR C677T polymorphisms as genetic predisposers to dementia. The study comprised of 80 vascular dementia patients, 90 degenerative dementia patients and 170 age matched controls. All were genotyped for ACE, MTHFR and APOE polymorphisms using PCR-RFLP method. Frequency of ACE D allele was seemingly high in dementia cases (26.7%) when compared to controls (11.2%). However, after adjusting for age and APOE E4^*, none of the ACE alleles showed good correlation. MTHFR genotypes or alleles also did not show any correlation. Our study suggests no true correlation of ACE or MTHR genes with dementia in elderly.     

Typologies of Alcohol Dependence. From Jellinek to Genetics and Beyond

The goal of typology research is to identify subtypes of alcohol dependent (AD) patients sharing fundamental characteristics and try to match each subtype, with the most precise treatment strategy. This review provides a comprehensive history of the literature on alcohol dependent subtypes starting from the earliest attempt made by Jellinek. The binary models identified most closely with Cloninger and Babor as well as the successively more complex classifications are discussed. Typology classification potentially useful in guiding the treatment of AD patients, especially in the case of the serotonergic medications. Contrasting data suggests that other factors could influence the response to a medication and/or that more complex typologies should be identified. In summary, typology models may assist in the ascertainment criteria for clinical trials performed in behavioral and pharmacotherapeutic interventions. Greater emphasis, however, must be made to more clearly delineate this field of research, while moving toward more standardized typologies.     

Sleep in children enhances preferentially emotional declarative but not procedural memories

Although the consolidation of several memory systems is enhanced by sleep in adults, recent studies suggest that sleep supports declarative memory but not procedural memory in children. In the current study, the influence of sleep on emotional declarative memory (recognition task) and procedural memory (mirror tracing task) in 20 healthy children (10-13 years of age) was examined. After sleep, children showed an improvement in declarative memory. Separate analysis with respect to the emotional stimulus content revealed that sleep enhances the recognition of emotional stimuli (p > .001) rather than neutral stimuli (p = .084). In the procedural task, however, no sleep-enhanced memory improvement was observed. The results indicate that sleep in children, comparable to adults, enhances predominantly emotional declarative memory; however, in contrast to adults, it has no effect on the consolidation of procedural memory.     

Does quality of sleep mediate the effect of depression on hopelessness?

The objectives of the study were to evaluate the relationship between sleep quality, depression, and hopelessness in advanced cancer patients and whether sleep quality mediated the effect of depression on hopelessness. The final sample consisted of 102 advanced cancer patients under palliative treatment. Patients completed the Greek Pittsburgh Sleep Quality Index, a sleep quality instrument, the Greek Beck Depression Inventory for measuring depression, and finally the Beck Hopelessness Scale. Patients' performance status was assessed by their overall physical functioning, as defined by the Eastern Cooperative Oncology Group. Depression was highly associated with hopelessness (r = .52, p<.001). Statistically significant associations were found between sleep quality with hopelessness (r = .37, p<.001), as well as with depression (r = .36, p<.001). Mediation analyses indicated that depression influenced hopelessness directly as well as indirectly by its effect on sleep quality. About 14.58% of the variation in hopelessness was explained by depression; 4% of the variance in hopelessness explained by depression was accounted for by the mediation pathway indicating that sleep quality mediated the relationship between depression and hopelessness. Similarly, in the reverse mediation analysis, depression mediated the relationship between sleep quality and hopelessness; 43% of the variation in hopelessness was explained by sleep quality. In conclusion, some of the effect of depression on hopelessness was mediated by sleep quality, but depression had a direct effect on hopelessness as well. Additionally, some of the effect of sleep quality on hopelessness was mediated by depression. The current findings are important because improving sleep quality by treating depression may contribute to decreased hopelessness scores and vice versa: Treating depression by improving sleep quality may also contribute to lower hopelessness scores.     

ERPs studies of cognitive processing during sleep

In the last few decades, several works on cognitive processing during sleep have emerged. The study of cognitive processing with event related potentials (ERPs) during sleep is a topic of great interest, since ERPs allow the study of stimulation with passive paradigms (without conscious response or behavioural response), opening multiple research possibilities during different sleep phases. We review ERPs modulated by cognitive processes during sleep: N1, Mismatch Negativity (MMN), P2, P3, N400-like, N300-N550, among others. The review shows that there are different cognitive discriminations during sleep related to the frequency, intensity, duration, saliency, novelty, proportion of appearance, meaning, and even sentential integration of stimuli. The fascinating results of cognitive processing during sleep imply serious challenges for cognitive models. The studies of ERPs, together with techniques of neuroimaging, have demonstrated the existence of cognitive processing during sleep. A fundamental question to be considered is if these cognitive phenomena are similar to processing that occurs during wakefulness. Based on this question we discussed the existence of possible mechanisms associated with sleep, as well as the specific cognitive and neurophysiologic differences of wakefulness and sleep. Much knowledge is still required to even understand the conjunction of dramatic changes in cerebral dynamics and the occurrence of cognitive processes. We propose some insights based on ERPs research for further construction of theoretical models for integrating both cognitive processing and specific brain sleep dynamics.     

Development of adolescence‐limited,late‐onset,and persistent offenders from age 8 to age 48

This article investigates the life success at ages 32 and 48 of four categories of males: nonoffenders, adolescence‐limited offenders (convicted only at ages 10–20), late‐onset offenders (convicted only at ages 21–50), and persistent offenders (convicted at both ages 10–20 and 21–50). In the Cambridge Study in Delinquent Development, 411 South London males have been followed up from age 8 to 48 in repeated personal interviews. There was considerable continuity in offending over time. Persistent offenders had the longest criminal careers (averaging 18.4 years), and most of them had convictions for violence. Persistent offenders were leading the most unsuccessful lives at ages 32 and 48, although all categories of males became more successful with age. By age 48, the life success of adolescence‐limited offenders was similar to that of nonoffenders. The most important risk factors at ages 8–18 that predicted which offenders would persist after age 21 were heavy drinking at age 18, hyperactivity at ages 12–14, and low popularity and harsh discipline at ages 8–10. The most important risk factors that predicted which nonoffenders would onset after age 21 were poor housing and low nonverbal IQ at ages 8–10, high neuroticism at age 16, and anti‐establishment attitudes and motoring convictions at age 18. It was suggested that nervousness and neuroticism may have protected children at risk from offending in adolescence and the teenage years. Aggr. Behav. 35:150–163, 2009. © 2009 Wiley‐Liss, Inc.     

Experimental manipulation of maternal proximity during short sequences of sleep and infant calming response

This study aimed to understand how different mother-infant sleeping arrangements impact infants’ self-regulation, particularly their calming response. Thus this study investigated the effect of three prevalent mother-infant sleeping arrangements, co-sleeping (CS), sleeping beyond arm’s length from their mother (BAL), and solitary sleeping (SS), on infants’ physiological calming through self-regulation during a nap session in 24 infants (50% female, M = 1.85 months SD = 0.93 months), who were identified as either regular co-sleepers with their mothers, infants who slept in the BAL sleeping arrangement from their mother, and infants who are solitary sleepers (SS). The effect of all three sleeping conditions amongst all the three types of infants with different habitual sleeping arrangements was assessed. All infants spent 10 min (2 × 5 min sessions) in each sleeping condition (CS, BAL, SS) during which electrocardiographic recordings were collected to obtain interbeat intervals (IBI) and rMSSD, a measure of heart rate variability (HRV) an index of physiological calming, maintained by the parasympathetic pathway involved in self-regulation. Infants who regularly co-slept with their mothers had the highest IBI, indicating greater physiological calming and self-regulation across all sleeping arrangement conditions (CS, BAL, SS), followed by infants who regularly slept in the BAL sleeping arrangement from their mothers. IBI was lowest amongst regular solitary sleepers, potentially indicating physiological stress due to mother-infant separation. However, HRV indices during the sleeping arrangements (especially across regular solitary sleepers) were inconclusive as to whether the lack of change in HRV across all sleeping conditions was due to physiological stress responses or greater physiological regulation. This study is the first to investigate the effect of manipulated and habitual mother-infant sleeping arrangements on infant physiological calming.