Editorial on the Research Topic Mood and Cognition in Old Age Depression and cognitive impairment are great challenges for the elderly population. The Research Topic “Mood and Cognition” by Frontiers in Aging Neurosciences comprises 16 articles addressing new findings and perspectives concerning mood and cognition in old age, including age-related disorders (e.g., elderly depression, mild cognitive impairment, and Alzheimer's disease). The articles presented focus on the role of the brain structure and activity in mood and cognition and explore several hypotheses regarding their association with new pathophysiological processes such as inflammation, the association with other comorbidities, as well as the impact of invasive medical procedures on cognition and delirium. Other approaches are focused on the influence of socialization, interpersonal relations, and social learning on cognitive performance and quality of life. Three articles are focused on the connection between dementia (Alzheimer's Disease-AD) and depression. Liu et al., conducted a study explaining how the hypothalamus interacts with other brain regions in AD patients with depression (D-AD), using a functional connectivity (FC) analysis. This promising study showed that D-AD patients had reduced FC in the hypothalamus, the right middle temporal gyrus and the right superior temporal gyrus compared with the FC of nD-AD patients, and suggested that the abnormal FC between the hypothalamus and the temporal lobe may play a key role in the pathophysiology of depression in AD patients. Lebedeva et al., assessed whether structural brain magnetic resonance imaging (MRI) in late-life depressed patients (LLD) could predict mild cognitive impairment or dementia 1 year prior to the diagnosis. The authors concluded that the analysis of the baseline structural MRI alone was able to accurately distinguish LLD patients developing MCI and dementia, from those remaining cognitively stable. Moreover, the authors showed that the ventral diencephalon, including the hypothalamus, might play an important role in the preservation of cognitive functions in LLD. Following the same line, Liu et al. investigated the relationship among a history of depression, depressive states, and dementia in a community-based old-old cohort in Japan. This valuable study concluded that a history of depression should be considered a risk factor for all-cause dementia and that, in the old-old population, depression was associated with a higher prevalence of dementia, lower cognitive performance, and a smaller hippocampus. The study of Hou et al. examined the implicit relationship between the disruption of interhemispheric functional coordination and cognitive impairment in late-onset depression (LOD), using functional magnetic resonance imaging (fMRI). The authors state that the altered linkage patterns of intrinsic homotopic connectivity and impaired cognitive flexibility may constitute a novel clue regarding the neural substrates underlying cognitive impairment in LOD. Zhao et al. present a hypothesis and theory article focusing on post-stroke depression (PSD), which is a common neuropsychiatric complication in patients who have suffered a stroke. The authors explored the inflammation hypothesis for PSD and point to preventive and therapeutic strategies, specifically remote ischemic conditioning (RIC). They concluded that RIC may be a novel approach to prevent PSD, with potential to be widely used in clinical practice and to be applied in other neurobehavioral disorders. Moretti and Signori conducted a very interesting review regarding the neural correlates for apathy in frontal-prefrontal and parietal cortical-subcortical circuits. In spite of the controversial definitions, with different categorizations of this nosographical entity, the present discussion may contribute to new insights about apathy in the context of several pathologies being degenerative, vascular, acute, or chronic. The authors concluded by highlighting important future directions toward goal-specific problems. In their article Gamaldo et al. examine the rates, predictors, and outcomes of sleep disturbances in older hospitalized patients. This is the first study to use a large national (USA) healthcare database, with 35,258,031 of older adults. Stating that the proportion of older adults with a sleep diagnosis has increased significantly over the last decade, this study documented an important association between increasing sleep disturbance rates and expenditures within hospital settings. Moreover, co-morbidities such as depression, cardiovascular risk factors, and neurological disorders steadily increased over time in these patients. Also from the USA, Assari and Lankarani conducted a study focused on the reciprocal and longitudinal associations between depressive symptoms and mastery, comparing black and white American older adults. They found that, among white but not black older adults, higher levels of depressive symptoms at baseline predicted a greater decline in sense of mastery over 3 years' follow-up, stating that race may alter how depression is linked to changes in evaluation of self (e.g., mastery) over time. Focusing on cognition, the article of Palaci et al. explored how parental economic socialization affects the planning for retirement (FPR) through the mediation of financial literacy, financial planning decisions, and financial management. The results show that parental economic socialization directly and indirectly influences FPR, and that parental economic behavior acts as a positive model for the development of financial literacy and skills and for decisions about FPR. Based on this, the authors point out important future lines of research. Ouanes et al. conducted a population-based study, hypothesizing that increased cortisol may be associated with poorer cognition and with certain personality traits (mainly high neuroticism),...