Abstract / Summary
Background: Dementia and mental disorders are leading causes of disease burden in middle-aged and older adults. Existing evidence suggests close clinical and epidemiological associations between dementia and mental disorders. We aimed to characterize the concurrent features of dementia and eight mental disorders at both the individual level and the population level (temporal and spatial patterns of global burden of disease co-existence and co-occurrence). Methods: The study utilized data from the UK Biobank (UKB, N=502461, 2006-2021) and Global Burden of Disease (GBD, 204 countries, 1990-2021). In UKB, Cox models were used to explore associations between mental disorders and dementia and shared risk factors between the two conditions. In GBD, multi-state Markov models were constructed to quantify the expected time of concurrent burden. Results: There was a substantial concurrence between dementia and mental disorders, along with causal associations and shared risk factors at the individual level. At the country level, although a trend of decreased prevalence and incidence of dementia was observed in most regions over the past 31 years, dementia demonstrated greater co-existence burden of neurodevelopmental disorders (especially attention-deficit/hyperactivity disorder and idiopathic developmental intellectual disability) in Middle East and North Africa. In high- socio-demographic index areas such as Western Europe, and high-income north America countries, it was more linked to mental disorders including anxiety disorders, eating disorders, and schizophrenia. There was a high co-existence burden of neurodevelopmental disorders demonstrated with both early- and late-onset of dementia. Conclusions: Our findings underscore the urgent need for proactive, integrated, and life-course health management strategies to achieve precision prevention and control of dementia, mental disorders and their concurrence.