The Sleep Side of Aging and Alzheimer's Disease.

As we age, sleep patterns undergo significant modifications in micro and macrostructure, worsening cognition and quality of life. These are associated with remarkable brain changes, like deterioration in synaptic plasticity, gray and white matter, and significant modifications in hormone levels. Sleep alterations are also a core component of mild cognitive impairment (MCI) and Alzheimer's Disease (AD). AD night time is characterized by a gradual decrease in slow-wave activity and a substantial reduction of REM sleep. Sleep abnormalities can accelerate AD pathophysiology, promoting the accumulation of amyloid-ß (Aß) and phosphorylated tau. Thus, interventions that target sleep disturbances in elderly people and MCI patients have been suggested as a possible strategy to prevent or decelerate conversion to dementia. Although cognitive-behavioral therapy and pharmacological medications are still first-line treatments, despite being scarcely effective, new interventions have been proposed, such as sensory stimulation and Noninvasive Brain Stimulation (NiBS). The present review outlines the current state of the art of the relationship between sleep modifications in healthy aging and the neurobiological mechanisms underlying age-related changes. Furthermore, we provide a critical analysis showing how sleep abnormalities influence the prognosis of AD pathology by intensifying Aß and tau protein accumulation. We discuss potential therapeutic strategies to target sleep disruptions and conclude that there is an urgent need for testing new therapeutic sleep interventions.

Criteria for healthy urban environments.

Indicators derived from a taxonomy of environmental hazards to health can help in assessing the health of a city and its citizens. These criteria may also be related to a city's contribution to the health of its natural environment. The proposed indicators for the city's and the citizens' "sickness" and health are intended to form a matrix, modified by experience. This may generate a database for monitoring changes. Thereafter it could be applied to studies comparing the health of the built environment with that of its human inhabitants, and its natural environment. Ultimately such studies may be used to prevent health hazards to the city and to protect and promote city health. Once the causes of the variables of environmental and human health are determined, attention could also be given to aspects of human health not directly related to those of the city. I discuss the advantages of such a holistic approach over "salad" lists, single theory or issues, and fragmented approaches. The underlying problems of the human condition in cities are so nearly indeterminable and unaddressable that ultimately decisions on policies and their implementations must be based on intuition. However, good intuition works on the best information available.