A comprehensive global analysis spanning 31 years found that while dementia prevalence and incidence declined in most regions, the concurrent burden of mental health disorders with dementia varies dramatically by geography. In the Middle East and North Africa, dementia showed greater comorbidity with neurodevelopmental disorders like ADHD and intellectual disability. Conversely, in high-income Western regions including Europe and North America, dementia correlated more strongly with anxiety, eating disorders, and schizophrenia. The research identified neurodevelopmental disorders as highly comorbid with both early- and late-onset dementia across all regions. These geographic patterns suggest that genetic, environmental, or healthcare system factors may influence how dementia manifests alongside other neuropsychiatric conditions. The findings could reshape prevention strategies, as different regions may need tailored approaches targeting their specific comorbidity profiles. For individuals in high-income countries, addressing anxiety and metabolic factors early may be crucial, while those in middle-income regions might benefit from neurodevelopmental screening. However, this preprint awaits peer review, and the methodology for establishing these correlations requires scrutiny. If validated, this represents a paradigm-shifting understanding that dementia prevention must be regionally customized rather than universally applied.