{"id":32960,"date":"2026-02-05T16:27:30","date_gmt":"2026-02-05T07:27:30","guid":{"rendered":"https:\/\/sonomono.jp\/?p=32960"},"modified":"2026-08-03T17:53:41","modified_gmt":"2026-08-03T08:53:41","slug":"natto-hakase-90","status":"publish","type":"post","link":"https:\/\/sonomono.jp\/en\/natto-hakase\/natto-hakase-90\/","title":{"rendered":"Does Dehydration Affect Cognitive Function? Understanding Fluid Intake, Aging, and Dementia Risk"},"content":{"rendered":"\n

Can Reduced Fluid Intake Lead to Cognitive Decline?<\/h2>\n\n\n\n
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As humans age, declines in physical function, organ performance, and activities of daily living have been widely reported. In practice, many older adults experience reduced physical activity as well as decreased overall movement in daily life. Alongside these changes, some older individuals intentionally limit their intake of water and other beverages in an effort to reduce urinary frequency.<\/p>\n\n\n\n

At the same time, age-related cognitive decline has also been documented. In recent years, multiple medical studies have reported a potential association between reduced fluid intake and declines in cognitive function.<\/p>\n\n\n\n

Water accounts for approximately 55\u201360% of the human body and is an essential component for maintaining physiological balance. Estimated daily water requirements, including water obtained from food, are approximately 2.3\u20132.5 liters per day for individuals with low activity levels and 3.3\u20133.5 liters per day for those with higher activity levels.<\/p>\n\n\n\n

Because these estimates include water derived from food, it is generally recommended that people consume about 1.5 liters of drinking water per day to maintain adequate hydration.<\/p>\n\n\n\n

Adequate Hydration May Help Prevent Cognitive Decline<\/h2>\n\n\n\n

A research group led by Dr. Hideyuki Hoshi at Hokuto Hospital (Hokkaido, Japan) investigated the effects of fluid intake on dementia risk in 33 Japanese older adults residing in long-term care facilities.<\/p>\n\n\n\n

The study reported that when daily fluid intake was below 42 mL per kilogram of lean body mass (LBM), changes in cognitive performance\u2014measured using the MMSE-J score\u2014were observed. In addition, associations were found between fluid intake levels and cerebral hemodynamics (brain blood flow).<\/p>\n\n\n\n

The authors concluded that \u201cadequate fluid intake showed a linear association with improvements in cognitive function, and this effect may be mediated through cerebral blood flow dynamics.\u201d<\/p>\n\n\n\n

In other words, maintaining sufficient hydration may support normal cerebral blood circulation and potentially help mitigate age-related cognitive decline.<\/p>\n\n\n\n

LBM (Lean Body Mass)<\/em> refers to body weight excluding fat mass.
MMSE-J<\/em> is the Japanese version of the Mini-Mental State Examination, a widely used tool for assessing cognitive function.<\/p>\n\n\n\n

Does Green Tea Support Cognitive Health?<\/h2>\n\n\n\n
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Beyond hydration alone, attention has also focused on beverages that provide both fluids and bioactive compounds\u2014particularly green tea.<\/p>\n\n\n\n

A research team led by Dr. Shutaro Shibata from the Department of Neurology at Kanazawa University examined data from the JPSC-AD Study<\/em>, a large dementia cohort in Japan. The analysis included 8,766 individuals without dementia who had available brain MRI data. Researchers evaluated associations between coffee and green tea consumption and brain white matter lesions, hippocampal volume, and total brain volume.<\/p>\n\n\n\n

Participants were categorized into four groups based on daily intake:<\/p>\n\n\n\n