When distraction is not distracting: a behavioral and ERP study on distraction in ADHD.

OBJECTIVE: Although an increased distractibility is one of the behavioral criteria of Attention Deficit Hyperactivity Disorder (ADHD), there is little empirical evidence that children with ADHD are in fact more distractible than their normal peers. METHODS: We recorded event-related potentials (ERPs) to distracting novel sounds (novels) and standard sounds, (standards) while children performed a visual two-choice reaction time task. Twenty-five children with ADHD were compared with eighteen normal controls (aged 8-12 years). RESULTS: Children with ADHD showed a larger early P3a (150-250 ms), both in response to the standard and in response to the novel. The late phase of the P3a had a larger amplitude in the ADHD group in the 250-300 ms window compared to the control group, which was only present in response to the novel. Interestingly, the novel reduced the errors of omission in the ADHD group to a greater extent than in the normal control group. CONCLUSIONS: Although children with ADHD show an increased orienting response to novels, this distracting information can enhance their performance temporarily, possibly by increasing their arousal to an optimal level, as indicated by the reduced omission rate. SIGNIFICANCE: These data indicate that distraction is not always distracting in children with ADHD and that distraction can also have beneficial effects.

Peripheral electrical nerve stimulation and rest-activity rhythm in Alzheimer's disease.

Rest-activity rhythm disruption is a prominent clinical feature of Alzheimer's disease (AD). The origin of the altered rest-activity rhythm is believed to be degeneration of the suprachiasmatic nucleus (SCN). In accordance with the 'use it or lose it' hypothesis of Swaab [Neurobiol Aging 1991, 12: 317-324] stimulation of the SCN may prevent age-related loss of neurons and might reactivate nerve cells that are inactive but not lost. Previous studies with relatively small sample sizes have demonstrated positive effects of peripheral electrical nerve stimulation on the rest-activity rhythm in AD patients. The present randomized, placebo-controlled, parallel-group study was meant to replicate prior findings of electrical stimulation in AD in a substantially larger group of AD patients. The experimental group (n = 31) received peripheral electrical nerve stimulation and the placebo group (n = 31) received sham stimulation. Effects of the intervention on the rest-activity rhythm were assessed by using wrist-worn actigraphs. Near-significant findings on the rest-activity rhythm partially support the hypothesis that neuronal stimulation enhances the rest-activity rhythm in AD patients. Interestingly, post-hoc analyses revealed significant treatment effects in a group of patients who were not using acetylcholinesterase inhibitors concomitantly. We conclude that more research is needed before firm general conclusions about the effectiveness of electrical stimulation as a symptomatic treatment in AD can be drawn. In addition, the present post-hoc findings indicate that future studies on non-pharmacological interventions should take medication use into account.

Peripheral electrical stimulation in Alzheimer's disease.

In a number of studies, peripheral electrical nerve stimulation has been applied to Alzheimer's disease (AD) patients who lived in a nursing home. Improvements were observed in memory, verbal fluency, affective behavior, activities of daily living and on the rest-activity rhythm and pupillary light reflex. The aim of the present, randomized, placebo-controlled, parallel-group clinical trial was to examine the effects of electrical stimulation on cognition and behavior in AD patients who still live at home. Repeated measures analyses of variance revealed no effects of the intervention in the verum group (n = 32) compared with the placebo group (n = 30) on any of the cognitive and behavioral outcome measures. However, the majority of the patients and the caregivers evaluated the treatment procedure positively, and applying the daily treatment at home caused minimal burden. The lack of treatment effects calls for reconsideration of electrical stimulation as a symptomatic treatment in AD.

Effects of transcutaneous electrical nerve stimulation (TENS) on memory in elderly with mild cognitive impairment.

In previous studies, transcutaneous electrical nerve stimulation (TENS) was shown to have a positive effect on memory in Alzheimer's disease (AD) patients. Moreover, the reported effects appeared to be more beneficial in early stages of Alzheimer's disease compared to later stage intervention. Based on this stage-dependency, the present study examined the effects of TENS on memory in a preclinical stage of AD, i.e. in subjects with mild cognitive impairment (MCI). Our results suggest that TENS did not improve memory in a MCI population. Mechanisms that might underlie the absence of positive effects of the TENS treatment in a MCI population are discussed.

Effects of transcutaneous electrical nerve stimulation (TENS) on cognition, behavior, and the rest-activity rhythm in children with attention deficit hyperactivity disorder, combined type.

OBJECTIVE: The aim of this study was to examine the effects of transcutaneous electrical nerve stimulation (TENS) on cognition, behavior, and the rest-activity rhythm in children with attention deficit hyperactivity disorder, combined type (ADHD-CT). METHODS: Twenty-two children diagnosed with ADHD-CT received TENS treatment during 6 weeks, 2 times 30 min a day. Neuropsychological tests were administered to assess cognition, parent/teacher behavioral rating scales were used to measure behavior, and actigraphy was used to assess the rest-activity rhythm. RESULTS: TENS appeared to have a moderate beneficial influence on cognitive functions that load particularly on executive function. There was also improvement in behavior as measured by parent/teacher behavioral rating scales. Moreover, motor restlessness during sleep and motor activity during the day decreased by TENS. CONCLUSIONS: The effects of TENS in children with ADHD are modest but encouraging and warrant further research.

Effects of transcutaneous electrical nerve stimulation (TENS) on self-efficacy and mood in elderly with mild cognitive impairment.

In previous studies, transcutaneous electrical nerve stimulation (TENS) has been applied to patients with either Alzheimer's disease (AD) or incipient dementia, resulting in an enhancement in memory and verbal fluency. Moreover, affective behavior was shown to improve. Based on the positive effects of TENS in AD, it was hypothesized that TENS would improve self-efficacy in nondemented elderly with mild cognitive impairment (MCI) who live in a residential home. Four outcome measures, that is, a Dutch translation of the General Self-Efficacy Scale (Algemene Competentie Schaal), the Groninger Activity Restriction Scale, the Philadelphia Geriatric Center Morale Scale, and the Geriatric Depression Scale, were administered. Overall, the results suggest that the experimental group showed a mild improvement in self-efficacy and mood. In contrast, the placebo group showed a considerable reduction in self-efficacy and an increase in depression. Limitations of the present study and suggestions for future research are discussed.

Non-pharmacological interventions in cognitively impaired and demented patients--a comparison with cholinesterase inhibitors.

The present paper reviews studies examining the effects of non-pharmacological stimulation, i.e. bright light, physical activity and tactile stimulation (touch), on cognition, affective behaviour, and the sleep-wake rhythm of impaired and demented elderly, both in a qualitative (narrative) and quantitative (meta-analytic) manner. An extensive search through eight bibliographic data bases (PubMed, Web of Science, ERIC, PsychINFO, Psyndex, Cinahl, Biological Abstracts and Rehabdata) was performed up to August 2002. The primary criterion for inclusion in this review was that studies provided sufficient data to calculate effect-sizes. In the qualitative analysis, all three types of stimulation appeared to improve cognitive functioning. Disturbances in behaviour react positively to bright light and tactile stimulation. Bright light was also beneficial to sleep. Tactile stimulation had, moreover, a beneficial influence on the patient-caretaker relationship. A comparison was made with several representative papers published since 1991 on the effects of acetylcholinesterase inhibitors on cognition and behaviour with representative papers on non-pharmacological stimulation interventions. Data indicated that improvements in cognition and affective behaviour by non-pharmacological interventions (d' = 0.32) and by cholinesterase inhibitors (d' = 0.31) were of similar effect-size. Possible mechanisms underlying the non-pharmacological stimulation effects are discussed and suggestions offered for future research.

Effects of transcutaneous electrical nerve stimulation (TENS) on non-pain related cognitive and behavioural functioning.

An extensive search through nine electronic bibliographic databases (PubMed, Cochrane Library, Web of Science, ERIC, PsychINFO, Psyndex, Cinahl, Biological Abstracts, Rehabdata) was performed in order to review the effects of Transcutaneous Electrical Nerve Stimulation (TENS) on non-pain related cognitive and behavioural functioning. Eight studies were identified on neglect due to stroke, six studies on Alzheimer's disease (AD), one study on aging, and two studies on coma due to traumatic brain injury. The results of the various studies revealed that TENS has a variety of effects. These consist of enhancement of somatosensory functioning, visuo-spatial abilities and postural control in neglect, improved memory, affective behaviour and rest-activity rhythm in AD and acceleration of awakening in coma. Effectiveness of TENS is discussed in relation to various stimulation parameters: duration, frequency, pulse width and intensity. It is argued that arousal may underlie the beneficial influence of TENS in various conditions. Finally, suggestions are offered for future research.