Background: Neuropsychiatric symptoms (NPS) are common in patients with mild cognitive impairment (MCI) and associated with greater functional impairment. NPS may precede the onset of cognitive decline. Thus, recognition of NPS will become increasingly important. Premorbid personality traits might be another potential risk factors of NPS in MCI patients. However, there are still restricted numbers of studies with conflicting data.
Objectives: To examine the association between premorbid personality traits and NPS in patients with MCI.
Methods: This is an observational study of adults aged 
50 years with MCI (n = 83). Data collection was performed using a personal information questionnaire, the Thai version of Mini-Mental State Examination (TMSE), Montreal Cognitive Assessment (MoCA), Neuropsychiatric Inventory Questionnaire (NPI-Q) and International Personality Item (IPIP). Demographic data were analyzed by frequency and percentage. The associated factors of NPS were analyzed using Chi-square, t - test, univariate and multivariate logistic regression.
Results: Among 83 subjects with the mean age of 72.0 
7.1, 61.4% were female. The prevalence of NPS was 67.5%. The most common symptoms were irritability (34.9%), sleep problems (31.3%) and anxiety (26.5%), respectively. Premorbid emotionally stable and agreeableness personality trait were significantly lower in MCI with NPS compared to those without NPS (P < 0.05). The low emotionally stable trait was found to be significantly associated with anxiety and sleep problems in MCI patients (P < 0.05). After adjusting for age, gender, education, duration of symptoms, MoCA score, history of psychiatric disorder, psychiatric drugs and cognitive enhancing drugs in a multivariate model, low emotionally stable trait was independently associated with NPS in MCI (OR 0.62, 95% CI 0.38 to 1.00).
Conclusions: MCI subjects with NPS differ in their premorbid personality traits compared to those without NPS. The low premorbid emotionally stable could be considered as one risk factor for NPS in MCI patients.