Prevalence of Neuropsychiatric Symptoms across the Declining Memory Continuum: An Observational Study in a Memory Clinic Setting

AIMS: The study aimed to compare the frequency of neuropsychiatric symptoms (NPS) across the declining memory continuum, from normal aging, subjective cognitive impairment (SCI), and mild cognitive impairment (MCI) to Alzheimer's disease (AD), and to explore the clinical correlates of NPS. METHOD: In a memory clinic, 157 subjects (46 mild AD patients, 38 MCI individuals, 24 SCI subjects, and 49 normal controls) completed the neurobehavioral assessments with the Neuropsychiatric Inventory (NPI). The clinical significance of each NPI domain was defined as an item score ≥4. Result: Clinically significant depression was more common in the SCI than in the normal control group (p < 0.05). The frequency of NPS was significantly greater in the mild AD group compared to other groups. Clinically significant apathy and aberrant motor behavior were more common among the AD group than the MCI group (p < 0.05). The MMSE score (OR 4.84, 95% CI 1.92–12.16, p = 0.001) and apathy (OR 12.73, 95% CI 1.48–109.68, p = 0.021) significantly determined the diagnostic status as MCI or mild AD. CONCLUSION: Across the declining memory continuum, the frequency of NPS was highest among mild AD patients. Depression, apathy, and aberrant motor behavior deserve more attention. Presence of apathy might be an independent determinant for mild AD.