Microstructural abnormalities in white matter (WM) are often reported in Alzheimer's disease (AD) and may reflect primary or secondary circuitry degeneration (i.e., due to cortical atrophy). The interpretation of diffusion tensor imaging (DTI) eigenvectors, known as multiple indices, may provide new insights into the main pathological models supporting primary or secondary patterns of WM disruption in AD, the retrogenesis, and Wallerian degeneration models, respectively. The aim of this review is to analyze the current literature on the contribution of DTI multiple indices to the understanding of AD neuropathology, taking the retrogenesis model as a reference for discussion. A systematic review using MEDLINE, EMBASE, and PUBMED was performed. Evidence suggests that AD evolves through distinct patterns of WM disruption, in which retrogenesis or, alternatively, the Wallerian degeneration may prevail. Distinct patterns of WM atrophy may be influenced by complex interactions which comprise disease status and progression, fiber localization, concurrent risk factors (i.e., vascular disease, gender), and cognitive reserve. The use of DTI multiple indices in addition to other standard multimodal methods in dementia research may help to determine the contribution of retrogenesis hypothesis to the understanding of neuropathological hallmarks that lead to AD.

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Major depressive disorder (MDD) is a leading cause of disability worldwide. Current first line therapies target modulation of the monoamine system. A large variety of agents are currently available that effectively alter monoamine levels; however, approximately one third of MDD patients remain treatment refractory after adequate trials of multiple monoamine based therapies. Therefore, patients with treatment-resistant depression (TRD) may require modulation of pathways outside of the classic monoamine system. The purpose of this review was thus to discuss novel targets for TRD, to describe their potential mechanisms of action, the available clinical evidence for these targets, the limitations of available evidence as well as future research directions. Several alternate pathways involved in the patho-etiology of TRD have been uncovered including the following: inflammatory pathways, the oxidative stress pathway, the hypothalamic-pituitary-adrenal (HPA) axis, the metabolic and bioenergetics system, neurotrophic pathways, the glutamate system, the opioid system and the cholinergic system. For each of these systems, several targets have been assessed in preclinical and clinical models. Preclinical models strongly implicate these pathways in the patho-etiology of MDD. Clinical trials for TRD have been conducted for several novel targets; however, most of the trials discussed are small and several are uncontrolled. Therefore, further clinical trials are required to assess the true efficacy of these targets for TRD. As well, several promising novel agents have been clinically tested in MDD populations, but have yet to be assessed specifically for TRD. Thus, their applicability to TRD remains unknown.

Background Impacts of social isolation measures imposed by COVID-19 Pandemic on mental health and quality of life of older adults living with dementia and their caregivers remain unexplored. Studies have shown that psychoeducational and psychosocial interventions can manage behavioral and psychological symptoms in dementia (BPSD) and reduce the emotional burden on family members when applied in home-setting scenarios. Method a comprehensive systematic review of useful interventions for easing the BPSD burden in patients with dementia (PwD) and their caregivers in the context of COVID-19 quarantine was performed from January 2010 to March 2020. Results From a total of 187 articles retrieved from electronic databases (MEDLINE, LILACS, Cochrane and SCOPUS), 43 studies were eligible for this review. Most of the psychosocial and psychoeducational interventions described were person-centered strategies based on the cognitive-behavioral approach or informational tools to enhance care providers’ knowledge of dementia. Most studies achieved successful results in handling BPSD and mood-anxiety symptoms of care providers, contributing to an overall improvement in dyad life quality. Conclusion Evidence from the last few years suggest that low-cost techniques, tailored to the dyad well-being, with increasing use of technology through friendly online platforms and application robots, can be an alternative to conventional assistance during COVID-19 Pandemic. Nevertheless, the world’s current experience regarding the duration of the COVID-19 Pandemic and its effects on the cognition, behavior, and life quality of PwD will demand research on preventive and protective factors of dementia and the pursue of efficient interventions in different scenarios.