Objective <p>Mental disorders impose a substantial economic burden, making updated cost estimates essential for informed policymaking. This study provides recent cost-ofillness estimates for mental disorders in the general population and examines trends over a 12-year period.</p> Method <p>The Netherlands Mental Health Survey and Incidence Study (NEMESIS) is a cohort representative for the Dutch population in which common DSM-IV/DSM-5 mental disorders (mood disorders, anxiety disorders, substance use disorders and attention-deficit/hyperactivity disorder) were diagnosed using the Composite International Diagnostic Interview 3.0. In baseline data of NEMESIS-3 (2019-2022, N=6,194, age 47.9±16.4 years, 50.4% women) we estimated healthcare, productivity, travel costs associated with mental disorders through weighted regression models and compared these estimates with baseline data from NEMESIS-2 (2007-2009; N=6,506, age 44.3±12.5 years, 55.2% women), assuming identical unit prices.</p> Results <p>Total annual per capita costs of any mental disorder were €5,630. Productivity costs comprised the largest share of total costs (61%-85%). In all conditions, except substance use disorder, both total annual costs and productivity costs were lower in 2019-2022 compared to 2007-2009. Healthcare costs were substantially lower for mood and substance use disorders in 2019- 2022, even though primary healthcare utilization was increased in 2019-2022.</p> Discussion <p>Productivity costs are the primary cost driver of mental disorders. While primary care utilization has increased– possibly due to the introduction of general practice mental health professionals– healthcare resource use has decreased over time. This may indicate a shift in service provision toward primary care from specialized mental healthcare, potentially contributing to more cost-effective mental healthcare delivery.</p>