Background: Neuropsychiatric symptoms (NPS) have a major impact in persons with dementia (PwD). The interaction between the caregiver and the person with dementia may be related to the emergence of NPS. The concept of expressed emotion (EE) is used to capture this dyadic interaction. Objectives: The aim of the present study is to examine longitudinally the association between EE in caregivers and NPS in PwD living at home. Design: A longitudinal cohort study with 2 years of follow-up. Setting: PwD and their informal caregivers living at home in the south of the Netherlands. Participants: 112 dyads of PwD and their caregivers from the MAAstricht Study of BEhavior in Dementia. Main outcome measures: EE was measured at baseline with the Five-Minute Speech Sample and was used to classify caregivers in a low-EE or high-EE group. Associations between EE and neuropsychiatric subsyndromes (hyperactivity, mood and psychosis) measured with the Neuropsychiatric Inventory (NPI) were analysed over time. Results: Seventy-six (67.9%) caregivers were classified in the low-EE group and 36 (32.1%) in the high-EE group. There was no difference between the EE groups in mean NPI scores over time. In the high-EE group, hyperactivity occurred more frequently than in the low-EE group at baseline (p=0.013) and at the other time points, but the mean difference was not always significant. There were no differences for the mood and psychosis subsyndromes. PwD with caregivers scoring high on the EE subcategory critical comments had an increased risk of institutionalisation (OR 6.07 (95% CI 1.14 to 32.14, p=0.034)) in comparison with caregivers scoring low on critical comments. Conclusions: High EE in informal caregivers is associated with hyperactivity symptoms in PwD. This association is likely to be bidirectional. Future studies investigating this association and possible interventions to reduce EE are needed.