高齢者における立位バランスと認知課題処理能力の関係について : 二重課題を用いた検討

先行研究によれば,バランス障害を有する高齢者は,立位保持と計算,数字の復唱などの認知課題とを同時に行った場合,バランス障害のない高齢者と比較して,有意に重心動揺が増加するとされている.本研究では,高齢者に,立位保持課題と認知課題(ストループテスト)を同時に行わせた場合と,それらを単一に処理した場合とで,立位保持課題と認知課題それぞれの処理能力にどのような変化がみられるのかを比較,検討した.対象は,65歳以上の高齢者であり,Berg Balance Scaleの得点により,彼らをバランス良好群(14名)とバランス不良群(9名)の2群に編成した.立位保持能力と認知課題処理能力の指標として,足圧中心変位の総軌跡長(Length: LNG)とストループテストの処理時間を用いた.バランス不良群では通常立位でのLNGとストループカラーテストを処理しながらのLNGの間に有意差が認められ,また,座位におけるストループカラーテストの処理時間と,立位におけるストループカラーテストの処理時間との間にも有意差が認められた.バランス良好群では,二重課題を行なってもLNGとストループテストの処理時間のどちらも影響を受けなかった.結果から,バランスの不良な高齢者は,立位保持と比較的複雑な認知課題を同時に行なうと,双方の処理能力が低下することが示唆され,これには,立位を保持するのに注意を必要とするかしないかが関係すると考えられた.

Antecedent research indicates that elderly persons with a balance disorder have significantly moreshifts in their body center of gravity than those with no balance disorder, while they simultaneouslyperform a task to maintain a standing position and a cognitive task such as calculation and repetition ofnumbers. In this research, a comparative study was made to identify what differences can be observed withrespect to elderly persons' abilities to deal with a task to maintain a standing position and a cognitive taskrespectively, in the following two cases: (1) when an elderly person performs both a task to maintain astanding position and a cognitive task (based on a the Stroop Test) simultaneously, and (2) when theelderly person performs the above tasks individually. Subjects were elderly persons of 65 years old or overand were organized into two groups based on scores of the Berg Balance Scale: the first group wascomposed of those who had good balance (14 persons); and the second group, poor balance (9persons).As an index to measure the ability to maintain a standing position and to perform a cognitive task,total excursion length (Length: LNG) of the shift in the center of pressure and the performance time forthe Stroop Test were used. Among the group with poor balance, differences in LNG were recognizedsignificantly between the two cases: when the subjects were in an ordinary standing position, and when thesubjects were performing the Stroop Color Test. Significant differences were also found in theperformance time for the Stroop Color Test between the two cases: when the subjects were in a sittingposition and when the subjects were in a standing position. Among the group with good balance, neitherLNG nor performance time for the Stroop Test were affected by performing both tasks simultaneously.The findings suggest that when elderly persons with bad balance deal with a task to maintain a standingposition and a cognitive task with a relative complexity simultaneously, the performance ability for bothtasks decreased. Thus, it is considered that whether or not a person needs to pay attention to maintain astanding position is involved in the decreased performance ability.