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.
In previous studies, transcutaneous electrical nerve stimulation (TENS) R ecent reviews indicate that the clinical hallmark of patients with mild cognitive impairment (MCI) is impaired memory in combination with a preservation of general cognition and activities of daily life.1,2 This type of MCI has also been called "amnestic" MCI 2 or "singledomain" MCI 3 and is probably caused by degeneration of various structures of the medial temporal lobe such as the hippocampus, the parahippo-campus, the entorhinal cor-tex, and the perirhinal cortex. 4 As opposed to single-domain MCI, patients with MCI may also show additional impairments in other cognitive functions, for example, orientation. 5,6 Patients with this type of MCI-called "multi-domain" MCI-have an even higher risk of developing probable Alzheimer's disease (AD) than those with single-domain MCI. Support for multi-domain MCI emerges from the finding that following the involvement of the medial temporal lobe, 4 the prefrontal cortex is also involved in MCI. [7][8][9] Indeed, an increased choline acetyltransferase (ChaT) activity has been observed in both the hippocampus and the frontal cortex of patients with MCI.10 This finding suggests a compensatory upregulation of the cholinergic system. The prefrontal cortex has been associated with executive functions such as planning, taking initiatives, and purposeful action/goal-directed behavior.11 In view of the nature of executive functions, it is logical that they are related to an individual's independent functioning. Specifically, executive functions appear to be a strong predictor for performance of (instrumental) activities of daily living. 12,13 In addition to a frontal lobe dysfunction as observed in MCI associated with decline in independent functioning, the institutional environment of a residential home for the elderly might augment an elderly resident's decline in independent functioning, irrespective of cognitive impairment. Richardson et al. 14 observed that a 1-year institutionalization caused an increase in functional limitations and a decrease in activities of daily living in about one third of the residents. Indeed, instrumental daily activities such as shopping, preparing meals, and cleaning the room are not required anymore in a residential home for the
SUMMAR Y 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 Ôuse it or lose itÕ hypothesis of Swaab [Neurobiol Aging 1991, 12: 317-324] stimulation of the SCN may prevent agerelated 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 ¼ 31) received peripheral electrical nerve stimulation and the placebo group (n ¼ 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.
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.
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