Prevalence and incidence of young onset dementia and associations with comorbidities: A study of data from the French national health data system

Abstract

Background Dementia onset in those aged <65 years (young onset dementia, YOD) has dramatic individual and societal consequences. In the context of population aging, data on YOD are of major importance to anticipate needs for planning and allocation of health and social resources. Few studies have provided precise frequency estimates of YOD. The aim of this study is to provide YOD prevalence and incidence estimates in France and to study the contribution of comorbidities to YOD incidence. Methods and findings Using data from the French national health data system (Système National des Données de Santé, SNDS) for 76% of the French population aged 40 to 64 years in 2016 (n = 16,665,795), we identified all persons with dementia based on at least 1 of 3 criteria: anti-Alzheimer drugs claims, hospitalization with the International Classification of Diseases-10th Revision (ICD-10) dementia code (F00 to F03, G30, G31.0, G31.1, or F05.1), or registration for free healthcare for dementia. We estimated prevalence rate (PR) and incidence rate (IR) and estimated the association of comorbidities with incident YOD. Sex differences were investigated. We identified 18,466 (PRstandardized = 109.7/100,000) and 4,074 incident (IRstandardized = 24.4/100,000 person-years) persons with prevalent and incident YOD, respectively. PR and IR sharply increased with age. Age-adjusted PR and IR were 33% (95% confidence interval (CI) = 29 to 37) and 39% (95% CI = 31 to 48) higher in men than women (p < 0.001 both for PR and IR). Cardio- and cerebrovascular, neurological, psychiatric diseases, and traumatic brain injury prevalence were associated with incident YOD (age- and sex-adjusted p-values <0.001 for all comorbidities examined, except p = 0.109 for antihypertensive drug therapy). Adjustment for all comorbidities explained more than 55% of the sex difference in YOD incidence. The lack of information regarding dementia subtypes is the main limitation of this study. Conclusions We estimated that there were approximately 24,000 and approximately 5,300 persons with prevalent and incident YOD, respectively, in France in 2016. The higher YOD frequency in men may be partly explained by higher prevalence of cardiovascular and neurovascular diseases, substance abuse disorders, and traumatic brain injury and warrants further investigation.

Global incidence of young‐onset dementia: A systematic review and meta‐analysis

“…Of these, 61 articles reported on the incidence of YOD and were included in this systematic review (eFigure A). 9,10,18–76 …”

Prevalence and trend of central nervous system–active medication polypharmacy among US commercially insured adults with vs without early-onset dementia: a multi-year cross-sectional study

“…The higher prevalence of CNS-active medication polypharmacy among patients with EOD (vs with LOD) is likely because the former group had a higher prevalence of seizures [ 6 ] and neuropsychiatric symptoms [ 7 ], leading to increased use of anticonvulsants and antidepressants, two commonly prescribed therapeutic classes of CNS-active medications observed in the study sample with EOD. Also, patients with EOD tended to have substance abuse and traumatic brain injury [ 8 ], risk factors associated with the use of multiple CNS-active medications observed in the present and previous studies [ 30 ]. The present study also observed a high percentage (43.5%) of patients with EOD who had a comorbid chronic pain diagnosis, a condition that strongly predicts the use of multiple CNS-active medications [ 18 ].…”

“…Compared with patients with LOD, those with EOD were more likely to develop seizures [ 6 ] and neuropsychiatric symptoms, such as depression (41% vs 26%), and anxiety (28% vs 14%) [ 7 ]. Also, patients with EOD have a high prevalence of substance abuse disorder (e.g., alcohol dependence; 14.6%) and traumatic brain injury (6.4%) [ 8 ], strong predictors of persistent opioid use [ 9 , 10 ]. Those conditions may predispose patients with EOD to the risk of using multiple CNS-active medications, or CNS medication polypharmacy.…”

Association Between Young-Onset Dementia and Risk of Hospitalization for Motor Vehicle Crash Injury in Taiwan

“…The 2 groups were frequency matched in a 1:1 ratio by age (within a 5-year span), sex, and index year, as implemented in other studies, 33 , 34 because these characteristics have been recognized as confounders for associations between traffic injuries and dementia. 18 , 21 , 35 For the group without dementia, the index date was January 1 of each year between 2006 and 2012.…”

“…For the group without dementia (reference group), we randomly selected individuals with no dementia diagnosis throughout the study period; the exclusion criteria for this cohort were the same as those used for the group with dementia. The 2 groups were frequency matched in a 1:1 ratio by age (within a 5-year span), sex, and index year, as implemented in other studies, because these characteristics have been recognized as confounders for associations between traffic injuries and dementia . For the group without dementia, the index date was January 1 of each year between 2006 and 2012.…”