水頭症と認知症

Hydrocephalus and Dementia

Point

・特発性正常圧水頭症（iNPH）は可逆性認知症の代表的疾患であり，前頭葉機能障害を中心に認知機能障害を呈する．

・iNPHでは，静的な行動・心理症状（アパシー，抑うつなど）が多く，アルツハイマー病とは異なる臨床像を示す．

・シャント術後には注意力・遂行機能が改善するが，記憶障害の改善は限定的である．

　Idiopathic normal pressure hydrocephalus (iNPH), also known as Hakim's disease, is a major cause of reversible dementia in adults. iNPH primarily affects frontal lobe-related cognitive functions, including attention, executive function, and working memory, even in early stages. Although memory impairment is also present, recognition memory is often preserved, distinguishing iNPH from Alzheimer's disease (AD). Behavioral and psychological symptoms of dementia (BPSD), especially apathy, depression, and anxiety, are common in iNPH and are generally less active than those seen in AD. Neuropsychological assessments reveal significant impairments in frontal lobe tests such as the Frontal Assessment Battery and Trail Making Test-B. Shunt surgery leads to substantial improvement in attention and executive function, reflecting the reversible nature of iNPH. However, memory functions, particularly delayed recall, show limited recovery, indicating possible overlap with neurodegenerative mechanisms. Early surgical intervention is associated with better outcomes, while delayed treatment or advanced brain atrophy may reduce effectiveness. Comprehensive cognitive evaluation is essential for assessing treatment response, planning rehabilitation, and providing appropriate patient and family guidance.