Abstract
Background: Treatment of Alzheimer as a disease that is associated with cognitive impairment has been associated with some restrictions. Recently, researchers have focused on non-pharmacological treatments, including non-invasive stimulation of the brain by transcranial electrical stimulation (tES). Four main paradigms of transcranial electrical current include transcranial direct current stimulation (tDCS), transcranial alternative current stimulation (tACS), transcranial random noise stimulation (tRNS), transcranial pulse current stimulation (tPCS). The tDCS is a possible new therapeutic option for patients with cognitive impairment, including Alzheimer disease. Materials and Methods: The study was done on Sprague-Dawley male rats weighing 250-270 g. to develop Alzheimer’s model, the cannula was implanted bilaterally into the hippocampus. Aβ 25-35 (5μg/ 2.5µl/day) was microinjected bilaterally for 4 days. Then, an electrical stimulation paradigm was applied to the animal for 6 days. Animal cognitive capacity was evaluated on day 11 and 12 by novel object recognition (NOR) test. Results: Our results showed that application of tDCS; tACS; tRNS and tPCS reversed beta-amyloid-induced impairment (P<0.05). The tRNS Group spent total exploration time around the objects compared to other groups (P<0.05). There was no significant difference between the four different paradigms in discrimination ratio and the percentage of total exploration time. Conclusion: The results of this study showed that the use of multiple sessions of different tES paradigms could improve Aβ-induced memory impairment in the NOR test. Therefore, based on evidence, it can be expected that in addition to using tDCS, other stimulatory paradigms may also be considered in the treatment of AD.
Highlights
Alzheimer disease (AD) is a progressive and irreversible neurodegenerative disorder which eventually leads to amnesia
The findings of this study revealed that repeated administration of Aβ 25-35 induced cognitive impairment in novel object recognition (NOR) test
The findings of the present study revealed that different paradigms of transcranial electrical stimulation (tES) prevented Aβ-induced cognitive impairment in the NOR test
Summary
Alzheimer disease (AD) is a progressive and irreversible neurodegenerative disorder which eventually leads to amnesia. Regarding the therapeutic constraints of AD by medication; induction of neuroplastic changes by non-invasive transcranial electrical stimulation (tES) techniques has been increasing in recent years [10] This technique is accomplished by generating direct current on the skull surface by using electrodes that are embedded in rubber coated with a sponge that is damped with saline or guiding gels [11]. One of the proposed mechanisms of tRNS is the increase of neuronal excitability via stochastic resonance, whereby weak neural signal detection in the central nervous system is enhanced when noise is added The advantages of this new technique, compared with tDCS, include the lack of sensitivity to the polarity of the electrodes and the reduction of skin sensitivity to the electrodes during stimulation [19].The tPCS is a direct current stimulation with a non-constant current in which the current is applied with a constant amplitude. Based on evidence, it can be expected that in addition to using tDCS, other stimulatory paradigms may be considered in the treatment of AD. [GMJ.2019;8:e1440] DOI:10.31661/gmj.v8i0.1440
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