Climate Change and Alzheimer’s Disease: An Emerging Neurological Crisis Mediated by Sleep Disruption

Abstract

Climate change has reached unprecedented levels and, according to the Intergovernmental Panel on Climate Change (IPCC), represents long-term shifts in climate patterns driven mainly by human-induced greenhouse gas emissions, resulting in a 1.1°C rise in global surface temperature between 1850-1900 and 2011-2020 [1].The year 2024 was the warmest on record, with an average global temperature of 15.10°C, 0.12°C higher than 2023 and 1.6°C above pre-industrial levels, marking the first year to surpass the 1.5°C threshold [2].Beyond environmental consequences, this accelerating warming trend poses a growing neurological health threat that could reshape global Alzheimer' s disease prevalence.Alzheimer' s, the most common form of dementia, is defined by amyloid plaques and neurofibrillary tangles, with amyloid beta accumulation beginning up to two decades before cognitive decline.The link between climate warming and Alzheimer's appears to operate through sleep disruption and its neurobiological consequences [3].A large-scale study analyzing over 23 million sleep nights found that for every 10°C increase in ambient temperature, deep sleep decreased by nearly 3 minutes and total sleep by about 10 minutes [4].Another study using wearable sleep trackers confirmed that elevated nighttime temperatures disrupt sleep globally, disproportionately affecting older adults and individuals in low-income countries [5].Yet, current epidemiological models have not accounted for the compounding effects of climate-induced sleep disruption on Alzheimer's pathogenesis during the decades preceding symptom onset.In older adults, sleep efficiency declines by 5%-10% when bedroom temperatures rise from 25°C to 30°C [6].Under current emission scenarios, global sleep insufficiency could increase by 10.5% by century's end, an annual loss of 33 hours of sleep per person [4].Over 1 billion people now experience at least 2 extra weeks per year with nights above 20°C, and 2.4 billion endure nights exceeding 25°C due to human-caused climate change [7].Such prolonged nighttime heat disrupts critical sleep stages essential for brain restoration.Multiple neurobiological pathways link thermal stress to Alzheimer's pathology, notably through dysfunction of the glymphatic system, a sleep-activated clearance network that removes neurotoxic proteins such as tau and beta-amyloid [8].Glymphatic activity peaks during deep non-rapid eye movement sleep, and its impairment precedes amyloid buildup, suggesting that decades of poor sleep may prime the brain for decline [9].Evidence is compelling: even one night of deprivation raises beta-amyloid levels [10], while chronic loss drives amyloid deposition and tau hyperphosphorylation [11].Short-term sleep deficiency increases insoluble tau by over 50% [12], and a 6-month study in adults aged 62-87 years found that deprivation correlated with posterior cingulate and hippocampal atrophy and reduced brain volume [13].The convergence of accelerating climate warming with Alzheimer's long latency period represents a silent but escalating public health threat.Current epidemiological models consider established dementia risk factors such as education and cardiovascular health, but overlook widespread sleep disruption caused by accelerating climate change.Today's middle-aged adults have experienced persistent nighttime