Time to Diagnosis in Dementia: A Systematic Review With Meta-Analysis.

Timely dementia diagnosis is a global priority, reflected in most national and regional policies and plans. Nevertheless, there are currently no robust estimates of the average time to diagnosis (TTD) and factors influencing diagnostic intervals. This article presents the first systematic review of quantitative studies on TTD in dementia and the factors associated with its duration. We systematically searched EMBASE, Psych INFO, MEDLINE, and CINAHL databases for relevant studies published up to December 2024. We defined TTD as the interval between symptom onset (rated by family carers or patients using interviews or medical records) to final diagnosis. Risk of bias was assessed using the Reporting studies on time to diagnosis tool. We included 13 studies reporting data on 30,257 participants, with age at onset ranging between 54 and 93 years. Meta-analysis pooling 10 studies showed that average mean TTD across all types of dementia was 3.5 years [confidence interval (CI): 2.7-4.3; moderate quality evidence]. Analyses of six studies showed that TTD in young onset dementia was 4.1 years (CI: 3.4-4.9; moderate quality evidence). Although the factors influencing TTD were inconsistent, a younger age at onset and having frontotemporal dementia were consistently associated with a longer interval to diagnosis. TTD in dementia remains long, and specific healthcare strategies are urgently needed to improve it. Increasing the evidence base and developing interventions to reduce TTD should be a future research priority. Specialist services are likely to be key in improving TTD in young-onset dementia.