Analysis of causal relationships by structural equation modeling to determine the factors influencing cognitive function in elderly people in Japan.

The purpose of this study is to identify a potentiality factor that is a preventive factor for decline in cognitive function. Additionally, this study pursues to clarify the causal relationship between the each potential factor and its influence on cognitive function. Subjects were 366 elderly community residents (mean age 73.7 ± 6.4, male 51, female 315) who participated in the Taketoyo Project from 2007 to 2011. Factor analysis was conducted to identify groupings within mental, social, life, physical and cognitive functions. In order to detect clusters of 14 variables, the item scores were subjected to confirmatory factor analysis. We performed Structural Equation Modeling analysis to calculate the standardization coefficient and correlation coefficient for every factor. The cause and effect hypothesis model was used to gather two intervention theory hypotheses for dementia prevention (direct effect, indirect effect) in one system. Finally, we performed another Structural Equation Modeling analysis to calculate the standardization of the cause and effect hypothesis model. Social participation was found to be activated by the improvement of four factors, and in turn, activated "Social participation" acted on cognitive function.

Horizontal visual search in a large field by patients with unilateral spatial neglect.

In this study, we investigated the horizontal visual search ability and pattern of horizontal visual search in a large space performed by patients with unilateral spatial neglect (USN). Subjects included nine patients with right hemisphere damage caused by cerebrovascular disease showing left USN, nine patients with right hemisphere damage but no USN, and six healthy individuals with no history of brain damage who were age-matched to the groups with brain right hemisphere damage. The number of visual search tasks accomplished was recorded in the first experiment. Neck rotation angle was continuously measured during the task and quantitative data of the measurements were collected. There was a strong correlation between the number of visual search tasks accomplished and the total Behavioral Inattention Test Conventional Subtest (BITC) score in subjects with right hemisphere damage. In both USN and control groups, the head position during the visual search task showed a balanced bell-shaped distribution from the central point on the field to the left and right sides. Our results indicate that compensatory strategies, including cervical rotation, may improve visual search capability and achieve balance on the neglected side.

Identification of three factors influencing trail making test performance using multichannel near-infrared spectroscopy.

Recent advances in medical care have facilitated the survival of patients with stroke or traffic-related injuries. However, such patients may suffer from higher brain dysfunction; i.e., an impaired ability to plan and perform behaviors based on prior knowledge. The Trail Making Test (TMT) is a cognitive task that is used to evaluate higher brain dysfunction caused by frontal lobe injury. TMT consists of two tasks; TMT-A involves connecting consecutive numbers, and TMT-B involves connecting numbers and letters alternately. In this study, using near-infrared spectroscopy (NIRS) and the achievement value (TMT score), we investigated the effects of three factors on TMT performance: knowledge of the TMT, the order of TMT-A and TMT-B performance, and gender. The subjects were 48 healthy adults, consisting of college graduates and undergraduates (age: 22.8 ± 2.5 years, education: 16.0 ± 1.2 years, 24 males and 24 females). We measured the changes in oxygenated hemoglobin (oxy-Hb) levels using NIRS, showing that the increase in oxy-Hb was higher in subjects who had no knowledge of the TMT than those who had prior knowledge. In both TMT-A and TMT-B, the subjects who performed their first task displayed higher oxy-Hb levels. Moreover, the oxy-Hb level in males was higher than that in females. In contrast, only the order of TMT performance showed noticeable effect on the TMT score. In the present study, using NIRS we have shown that either knowledge of the TMT, the order of the TMT, or gender affects TMT performance, providing invaluable information for interpreting TMT results.