Frailtyとサルコペニア

今日はWJ Evans, et al: Frailty and muscle metabolism dysregulation in the elderly. Biogerontology DOI 10.1007/s10522-010-9297-0を紹介します。

Frailtyとは、虚弱や脆弱性と訳され、ADLや体力が低下傾向の高齢者を意味します。Linda Fried のFrailtyの定義では、体重減少、著しい疲労感の自覚、（握力等の）低下、歩行速度の低下、活動レベルの低下のうち1つ当てはまると脆弱予備状態、2つで脆弱状態あり、3つでFrailtyとなります。最近のトピックの1つです。

Frailtyの最も大きな原因はサルコペニアだと考えます。サルコペニアからFrailtyに至る図を示します。拒食、不活動、炎症、ホルモン変化（インシュリン抵抗性含め）、慢性疾患などの結果、サルコペニアを生じ、そのためにFrailtyになるという流れです。

つまり、これらへの対策が重要となります。最も有効な治療方法はレジスタンストレーニングになりますが、その効果が出る栄養状態であるか、全身状態であるか、原疾患と栄養管理は適切かなどの条件が整っていなければ意味がありません。やはりリハ栄養的なアプローチが重要と考えます。

Abstract
The frailty syndrome is increasingly recognized
by geriatricians to identify elders at an
extreme risk of adverse health outcomes. The physiological
changes that result in frailty are complex
and up to now have been extremely difficult to
characterize due to the frequent coexistence of acute
and chronic illness. Frailty is characterized by an
decline in the functional reserve with several alterations
in diverse physiological systems, including
lower energy metabolism, decreased skeletal muscle
mass and quality, altered hormonal and inflammatory
functions. This altered network leads to an extreme
vulnerability for disease, functional dependency,
hospitalization and death. One of the most important
core components of the frailty syndrome is a
decreased reserve in skeletal muscle functioning
which is clinically characterized by a loss in muscle
mass and strength (sarcopenia), in walking performance
and in endurance associated with a perception
of exhaustion and fatigue. There are a number of
physiological changes that occur in senescent muscle
tissues that have a critical effect on body metabolism.
The causes of sarcopenia are multi-factorial and can
include disuse, changing hormonal function, chronic
diseases, inflammation, insulin resistance, and nutritional
deficiencies. In this review, we will explore the
dysregulation of some biological mechanisms that
may contribute to the pathophysiology of the frailty
syndrome through age-related changes in skeletal
muscle mass and function.