Physiological and psychological characterisation of young onset dementia: a case control study

Purpose: Young Onset Dementia (YOD) makes up around 5% of dementia cases and is linked to variousaetiologies and risk factors. Exercise is proposed to improve fitness and reduce cognitive decline, buttargeted interventions require understanding which physiological systems benefit.Aim: To compare physiological and psychological outcomes between YOD individuals and age/sexmatchedcontrols. It was hypothesised people with YOD would score lesser across all parameters.Methods: This study assessed body composition, blood pressure, dexterity, cognitive function, vascularfunction, muscle architecture, lung function, estimated maximal oxygen uptake (V̇ O 2max), functionalcapacity, physical activity, and mental wellbeing in YOD individuals (n=16) compared to controls(n=17).Results: YOD individuals showed significantly poorer outcomes in dexterity (left p = 0.013, d = 1.0;large effect, right p = 0.008, d = 1.0; large effect, both p <0.001, d = 1.40; large effect, Left + right +both p <0.001, d = 1.30; large effect, assembly p <0.001, d = 1.60; large effect), cognitive function (p<0.001, d = 3.60; large effect), muscle architecture (fascicle length: p=0.028, d=0.81; large effect),physical activity (Sedentary Time: p = 0.029, d = 0.54; moderate effect, Moderate-Vigorous PhysicalActivity (MVPA): p = 0.014, d=0.97; large effect), and mental wellbeing (Self Assessed Health RelatedQuality of Life - EQ-5D-3L analog score: p=0.007, d=1.10; large effect; General Self Efficacy Scale -GSE: p<0.001, d=1.29; large effect). No differences were found in estimated V̇ O2max, vascular function,muscle architecture (thickness, pennation angle and USI), lung function, functional capacity, and somemental wellbeing measures (Generalised Anxiety Disorder Assessment - GAD-7, Patient HealthQuestionnaire - PHQ-9, EQ-5D-3L index score, Pittsburgh Sleep Quality Index - PSQI).Conclusions: The study highlights significant physical, cognitive, and psychological differences inYOD individuals, underscoring the need for tailored, multicomponent exercise interventions. Thesefindings support future research to develop specific protocols to improve outcomes for YODindividuals, which should target dexterity, muscle architecture, estimated V̇ O 2max, and mentalwellbeing.