Drug addiction is a chronic disorder resulted from complex interaction of genetic, environmental, and developmental factors. Epigenetic mechanisms play an important role in the development and maintenance of addiction and also memory formation in the brain. We have examined passive avoidance memory and morphine conditioned place preference (CPP) in the offspring of male and/or female rats with a history of adulthood morphine consumption. Adult male and female animals received chronic oral morphine for 21days and then were maintained drug free for 10days. After that, they were let to mate with either an abstinent or control rat. Male offspring's memory was evaluated by step through test. Besides, rewarding effects of morphine were checked with CCP paradigm. Offspring of abstinent animals showed significant memory impairment compared to the control group which was more prominent in the offspring of abstinent females. Conditioning results showed that administration of a high dose of morphine (10mg/kg) that could significantly induce CPP in control rats, was not able to induce similar results in the offspring of morphine abstinent parents; and CPP was much more prominent when it was induced in the offspring of morphine exposed females compared to the progeny of morphine exposed males. It is concluded that parental morphine consumption in adulthood even before mating has destructive effects on memory state of the male offspring and also leads to tolerance to the rewarding effects of morphine. These effects are greater when the morphine consumer parent is the female one.

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Context: Patients with mild cognitive impairment (MCI) and Alzheimer’s disease (AD) are more likely to suffer from cognitive dysfunction due to dementia. Transcranial direct current stimulation (tDCS) as a non-invasive treatment strategy has been used as an efficient strategy to improve cognitive function. Evidence Acquisition: Several studies investigating tDCS over the dorsolateral prefrontal cortex (dlPFC) were reviewed. Results: Most of these studies have targeted the left dlPFC, indicating that tDCS over the dlPFC can improve cognitive function, such as memory, visual recognition, attention, decision-making, and cognitive decline. However, there are still many unanswered questions about the effect of tDCS over the dlPFC on the connectivity of this brain region as a key node for cognitive function. Meanwhile, further research should be conducted to elucidate the effects of tDCS over the dlPFC on brain connectivity and AD biomarkers. In addition, more investigations should be conducted to identify the exact mechanisms affecting dlPFC stimulation on cognitive dysfunction in AD patients. Conclusions: Based on the results, tDCS over the DlPFC could improve cognitive function in AD patients.