Alzheimer Disease: van Dijk KR

Scherder EJ, Luijpen MW, van Dijk KR. · Department of Clinical Neuropsychology, Vrije Universiteit, Van der Boechorststraat 1, 1081 BTAmsterdam, The Netherlands. · Chin J Physiol. · Pubmed #15074834 No free full text.

Abstract: In 1990 a series of studies started in which the effects of Transcutaneous Electrical Nerve Stimulation (TENS) was examined on cognition, behaviour, and the rest-activity rhythm of patients with Alzheimer's disease (AD). In these studies, TENS aimed primarily at stimulating the dorsal raphe nucleus (DRN) and the locus coeruleus (LC) by a combination of low- and high-frequency stimulation (2 Hz and 160 Hz, respectively), a pulse width of 0.1 ms, and an intensity that provokes muscular twitches. TENS was applied 30 min a day, during a six-week period. In order to make reliable comparisons between studies, identical stimulation-parameters were used in all studies thus far. TENS appeared to have a positive effect on cognition, behaviour, and the rest-activity rhythm but the effects disappeared after cessation of stimulation. In order to optimise TENS treatment in AD, the present paper is meant to reconsider the once selected stimulation-parameters by reviewing the relevant literature published since 1991. The results derived from animal experimental studies show that for an optimal stimulation of the LC and DRN, the pulse width should be more than 0.1 ms. Limitations and suggestions for future research will be discussed.

van Dijk KR, Scherder EJ, Scheltens P, Sergeant JA. · Department of Clinical Neuropsychology, Vrije Universiteit, Amsterdam, The Netherlands. · Rev Neurosci. · Pubmed #12405228 No free full text.

Abstract: 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.

van Dijk KR, Scheltens P, Luijpen MW, Sergeant JA, Scherder EJ. · Department of Clinical Neuropsychology, Vrije Universiteit, Amsterdam, The Netherlands. · Dement Geriatr Cogn Disord. · Pubmed #15802911 No free full text.

Abstract: 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.

Luijpen MW, Swaab DF, Sergeant JA, van Dijk KR, Scherder EJ. · Department of Clinical Neuropsychology, Vrije Universiteit, Van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands. · Behav Brain Res. · Pubmed #15698902 No free full text.

Abstract: 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.