Young-onset dementia — assessment and management (MEQ)

(i) Definition and differential

Young-onset dementia (YOD) is dementia with symptom onset before age 65 — an operational age cut-off that reweights causes rather than defining a single proteinopathy.[1][2] Global meta-analysis places age-standardised prevalence near 119 per 100,000 aged 30–64, underscoring service relevance.[2]

Differential (map by group): early-onset Alzheimer disease (EOAD); frontotemporal dementia (bvFTD/PPA); vascular cognitive impairment (including CADASIL teaching); DLB/PDD; alcohol-related brain injury; rapidly progressive mimics (CJD, autoimmune, infection, metabolic); and genetic-metabolic rarities (e.g. Wilson at younger ages). In under-65 series, AD, vascular disease, and FTD dominate many clinic mixes, with alcohol and mixed pathology important in some catchments.[1][10][12]

This stem (amnestic-dysexecutive/navigation/language, progressive, strong paternal early dementia) prioritises familial EOAD while still keeping FTD and other causes open until imaging/biomarkers clarify.[3][10]

(ii) Assessment and investigations

History: age at first symptom; tempo; domain of onset; work complexity; finances; driving; alcohol; head injury; three-generation pedigree (ages at onset, ALS, young stroke).[1][10]

Exam: MSE; MoCA/ACE-style cognition; full neurologic exam for dementia-plus signs (myoclonus, MND, parkinsonism, eye movements).[1][11]

Investigations: dementia bloods (FBC, U&E, LFT, glucose, B12, folate, TSH ± HIV/syphilis as indicated); MRI brain; consider CSF AD biomarkers if EOAD vs non-AD uncertain; genetics with counselling given early onset and first-degree early dementia (APP, PSEN1, PSEN2 panel teaching).[3][4][5][10][11]

(iii) Risk, capacity, employment, driving

Assess driving safety, occupational risk, financial exploitation, and home safety. Capacity is decision-specific (understand, appreciate, reason, communicate a choice — Appelbaum).[8] Document discussions about ceasing driving if unsafe; involve social work for income protection and workplace medical retirement pathways; plan enduring powers while residual capacity may allow participation.[8][11]

(iv) Management

If AD pathway is supported, trial a cholinesterase inhibitor: e.g. donepezil 5 mg orally daily, increase to 10 mg daily after 4 weeks if tolerated; monitor GI effects, sleep disturbance, bradycardia/syncope risk.[6] Non-drug care: OT, structured routine, carer support, age-appropriate YOD services (not aged-care-only templates).[1][11] Antipsychotics only for severe risk behaviours after non-drug measures; counsel increased mortality signal; lowest dose, shortest duration.[7] Do not automatically use AChEI for pure bvFTD if that becomes the diagnosis instead.[9]

(v) Genetic counselling

Paternal early dementia raises autosomal-dominant EOAD possibility (PSEN1 most frequent among the classic triad; also APP, PSEN2).[4][5] Offer pre- and post-test counselling; discuss implications for children; do not coerce predictive testing of asymptomatic relatives without formal genetics pathways.[10]