ObjectivesDetection of dementia is essential for improving the lives of patients but the extent of underdetection worldwide and its causes are not known. This study aimed to quantify the prevalence of undetected dementia and to examine its correlates.Methods/setting/participantsA systematic search was conducted until October 2016 for studies reporting the proportion of undetected dementia and/or its determinants in either the community or in residential care settings worldwide. Random-effects models calculated the pooled rate of undetected dementia and subgroup analyses were conducted to identify determinants of the variation.Primary and secondary outcome measuresThe outcome measures of interest were the prevalence and determinants of undetected dementia.Results23 studies were eligible for inclusion in this review. The pooled rate of undetected dementia was 61.7% (95% CI 55.0% to 68.0%). The rate of underdetection was higher in China and India (vs Europe and North America), in the community setting (vs residential/nursing care), age of <70 years, male gender and diagnosis by general practitioner. However, it was lower in the studies using Mini-Mental State Examination (MMSE) diagnosis criteria.ConclusionsThe prevalence of undetected dementia is high globally. Wide variations in detecting dementia need to be urgently examined, particularly in populations with low socioeconomic status. Efforts are required to reduce diagnostic inequality and to improve early diagnosis in the community.

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The long term effects of maternal smoking during pregnancy on the cognitive development of the child are not well understood due to conflicting findings in past research. The aim of this paper was to provide an up to date, critical review of the literature to determine whether there is evidence of a relationship between tobacco smoke exposure in utero and cognitive functioning. We systematically reviewed observational studies (dated 2000-2011) that examined associations between tobacco smoke exposure in utero due to maternal smoking and performance on cognitive, intelligence, neurodevelopmental and academic tests. Eligible studies were identified through searches of Web of Knowledge, Medline, Science Direct, Google Scholar, CINAHL, EMBASE, Zetoc and Clinicaltrials.gov databases. The review found evidence of a relationship between tobacco smoke exposure in utero and reduced academic achievement and cognitive abilities independent of other variables. Maternal smoking during pregnancy may therefore be a modifiable risk factor for reduced cognitive abilities later in the life of the child. Giving up smoking during pregnancy should be initiated as early as possible to reduce the impact on the child's cognitive development.

Recommendations should be made to the public to avoid sources of SHS and future research should investigate interactions between SHS exposure and other risk factors for delayed neurodevelopment and poor cognitive performance.

IMPORTANCE Both nonsuicidal self-injury (NSSI), defined as the direct, deliberate damage of one's body tissue without suicidal intent, and internet addiction among adolescents are public health concerns. However, the possible association of NSSI with internet addiction is not well understood. OBJECTIVE To examine the occurrence of internet addiction with NSSI and any sex differences among Chinese adolescents. DESIGN, SETTING, AND PARTICIPANTS A multicenter, cross-sectional, survey study was conducted from February 18 to October 15, 2015, among adolescents aged 11 to 20 years from 343 classes in 45 public high schools across 5 provinces of China. Data analysis was performed from