公衆衛生78巻10号

2014年10月発行

特集 認知症のケア

認知症の予防

著者： 島田裕之¹

所属機関： ¹国立長寿医療研究センター老年学・社会科学研究センター生活機能賦活研究部

ページ範囲：P.698 - P.702

認知症の危険因子と保護因子

　認知症の予防へ向けた取り組みを計画するには，その危険因子と保護因子を理解し，介入対象となる住民を特定する必要がある．年代別に認知症の危険因子をみると青年期における高等教育や，それ以降の知的活動は認知的予備力の向上と関連し，この認知的予備力は加齢による認知機能の低下に大きな影響は及ぼさないが，認知症発症抑制に寄与するかもしれないと考えられている¹⁾．中年期においては生活習慣病の管理が重要であり，高血圧，脂質異常症，糖尿病は脳血管疾患の危険因子であるとともにアルツハイマー病の危険因子でもあり，服薬管理，規則正しい食生活，運動習慣の確立が保護因子となる．高齢期には老年症候群などの因子が重要な認知症の危険因子となる．

　例えば，高齢期のうつ症状は，活動性を低下させ社会的孤立を招くとともに，脳由来神経栄養因子(brain-derived neurotrophic factor;BDNF)の発現を減少させる．BDNFの低下と海馬の萎縮は関連し²⁾，これが脳の予備力低下につながる．また，転倒などによる頭部外傷は将来のアルツハイマー病発症の危険因子である^3,4)．これらの高齢期における老年症候群などの因子を回避するためには，身体，認知，社会的活動を向上し，活動的なライフスタイルをいかにして確立していくかが高齢期の認知症予防対策として重要であると考えられる(図1)．

参考文献

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