Background: The study aimed to compare neuropsychiatric symptoms (NPS) in people with early-onset Alzheimer’s disease (EOAD) and late-onset AD (LOAD). Methods: Fifty-six participants with LOAD and 24 participants with EOAD having mild dementia were assessed for NPS for their frequency, severity, and caregiver distress as measured by Neuropsychiatry Inventory (NPI) along with assessments of cognition and functional dependence. Results: Participants with EOAD and LOAD were not significantly different for total NPI score ( P = .057). Early-onset Alzheimer disease had greater prevalence of all the NPS except apathy. Participants with EOAD were significantly worse on anxiety ( P = .03), irritability ( P = .01), and sleep ( P < .01) subscales and their carers significantly more distressed by their irritability ( P = .002) and sleeping patterns ( P = .005). Regression analysis showed that higher NPI score was associated with longer duration of illness in EOAD and higher functional dependence in LOAD. Conclusions: The NPS severity was similar between EOAD and LOAD although EOAD had higher symptom prevalence and carer distress.

Little is known about olfactory identification (OI) function in early-onset Alzheimer’s disease (EOAD) and early-onset mild cognitive impairment (eoMCI) with age of onset &lt;65 years. We aimed to study OI in EOAD compared with eoMCI and age-matched healthy controls (HC). Nineteen EOAD subjects with mild to moderate dementia, 17 with eoMCI, and 21 HC recruited as a convenience sample from memory services were assessed for cognition, behavioral symptoms, and activities for daily living. The OI was tested using the University of Pennsylvania smell identification test (UPSIT). EOAD participants performed worse compared with eoMCI and HC on cognitive tests and OI (p &lt; 0.001). Although eoMCI had poorer cognitive scores compared to HC, they were similar in their OI function. OI correlated with attention (r = 0.494, p = 0.031), executive functions (r = 0.508, p = 0.026), and praxis (r = 0.455, p = 0.05) within the EOAD group. OI impairment was significantly associated with the diagnosis of EOAD versus eoMCI, but not with eoMCI when compared with HC. OI could potentially be useful in differentiating EOAD from eoMCI. Studies with late-life MCI patients showing OI impairment relative to HC may be attributed to a different disease process. Independent replication in a larger sample is needed to validate these findings.