Several previous studies reported social participation may reduce the incident of dementia; therefore, the type of positions held in the organization may relate to dementia onset. However, this hypothesis remains largely unknown. The purpose of the present study was to examine the additive effect of a leadership position in the organization on dementia onset and social participation among elderly people in a local community, according to data from a Japanese older adults cohort study. Of 29,374 community-dwelling elderly, a total of 15,313 subjects responded to the baseline survey and were followed-up from November 2003 to March 2013. To evaluate the association between dementia onset and social participation as well as the role in the organization, we conducted Cox proportional hazard regression analysis with multiple imputation by age group (aged 75 years older or younger). The dependent variable was dementia onset, which was obtained from long-term care insurance data in Japan; independent variables were social participation and the role in the organization to which they belonged (head, manager, or treasurer). Covariates were sex, age, educational level, marriage status, job status, residence status, alcohol consumption, smoking status, and walking time, instrumental activities of daily living, depression, and medical history. During the follow-up period, 708 young-old elderly people (7.7%) and 1289 old-old elderly people (27.9%) developed dementia. In young-old elderly, relative to social non-participants, adjusted Hazard Ratio (HR) for dementia onset for participants (regular members + leadership positions) was 0.75 (95% confidence interval (CI), 0.64–0.88). Relative to regular members, adjusted HR for dementia onset for non-participants was 1.22 (95% CI, 1.02–1.46), for leadership positions 0.81 (95% CI, 0.65–0.99). The results for old-old elderly participants did not show that any significantly adjusted HR between dementia onset and social participation, the role in the organization. In young-old elderly people, social participation might have a positive effect on dementia onset, and holding leadership positions in organization could lead to a decrease in risk of dementia onset by almost 20% than regular members.

There have been increasing efforts to investigate the effects of neuromodulation techniques, such as transcranial direct current stimulation (tDCS), on cognitive impairment in dementia and related conditions. In this systematic review and meta-analysis, we assessed the efficacy of multisession anodal tDCS compared with sham stimulation for improving global cognition and specific cognitive domains in both Alzheimer’s disease and mild cognitive impairment. Eight articles meeting the criteria for inclusion in the meta-analysis were selected. Five studies used the Mini-Mental State Examination to examine mild cognitive impairment and dementia. In a fixed-effect model, there was a mean difference in the change score of −0.13 points. Three trials for dementia using the Alzheimer’s Disease Assessment Scale–Cognition showed a mean difference of −0.53 points. At present, there is a lack of clear evidence concerning the efficacy of multisession anodal tDCS due to the small number of studies and different measures used. This underscores the need for further investigations using larger samples and common outcome measures.

Positive symptoms of schizophrenia may be related to distortions in time perception. To examine this issue, we conducted a meta-analysis to determine whether positive symptoms are associated with deficits in time processing performance. MEDLINE and Web of Science were searched from January 1980 through March 2017, and all related articles and their references were scrutinized to find relevant studies. Studies were selected if they included participants with a diagnosis of schizophrenia, and reported data from behavioral measures of interval timing (e.g. duration discrimination and temporal order judgement). The results indicated that positive symptoms of schizophrenia are related with overestimation of interval timing (i.e., acceleration of the "internal clock"), and suggest that time perception may be associated with psychosis.