For early detection of ''potential patients with depression''. Correlation of sleep disorder with frontal lobe dysfunction and depression symptoms

In Phase I of the research field of ''mental health of workers'' among the 13 research fields for work-related injuries/illness etc. promoted by the Japan Labour Health and Welfare Organization, a statistical image analysis of cerebral blood flow single photon emission computed tomography (SPECT) (99mTc-ECD) was performed for 45 workers (a group of 25 patients with depression and a control group of 20 healthy workers) to perform objective assessment of the features of depression. In the depression and remission periods, we obtained findings regarding characteristic changes in cerebral blood flow, and local decreases in cerebral blood flow that correlated with the level of cumulative fatigue and subjective feelings of fatigue. Based on these image analysis results, it was suggested that for the prevention and early detection of depression, we should focus on the fact that patients with more severe sleep disorder(s) might show a decrease in blood flow in the dorsal frontal lobe, and that a close relationship between sleep disorder and depression was suggested in the images of cerebral function. Among 17 items of the Structured Interview Guide for the Hamilton Depression Rating Scale (SIGH-D) for the general evaluation of depression state, the patients with higher scores of sleep disorder, Insomnia Score (IS), showed a significant decrease in blood flow in the dorsal frontal lobe, suggesting a decrease in attentiveness/concentration. Focusing on the biological finding that showed a correlation between sleep disorder (IS) and frontal lobe dysfunction, we further examined the correlation between the level of sleep disorder, shown in IS, and the data related to depression (total SIGH-D score and the points of individual items; total score of the self-rating depressive scale [SDS] and points of individual items) in 108 workers (57 in the depression undergoing follow-up observation group and 51 in the healthy control group). As a result, IS in 57 subjects in the depression undergoing follow-up observation group showed a significant correlation with the level of depression (SIGH-D total score and SDS total score), feeling of fatigue, pessimistic feeling for the future, and suicidal ideation. Even in the 51 subjects in the control group, a significant correlation was confirmed between IS and the level of depression (SIGH-D total score and SDS total score). Based on these data, it was suggested that sleep-related interview items (IS) would be a useful basic interview item for prevention and early detection of depression, and prevention of suicide in the preventive medical field, including general health examination, etc., and in the field of occupational health. This research is a part of the research and development and the dissemination projects related to the 13 fields of occupational injuries and illnesses of the Japan Labor Health and Welfare Organization. (author)