The purpose of this study is to determine whether pain treatment can reduce symptoms of depression in patients suffering from dementia and depression. Depression is commonly diagnosed in patients with dementia. If the investigators find a reduction in depressive symptoms when pain treatment is applied, this will support the hypothesis that undiagnosed pain may present itself as depression in patients with dementia.

Inclusion Criteria:

• Patients residing in long term nursing home units for at least 4 weeks prior to study
• Diagnosed with probable or possible dementia according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), FAST score > 4
• Diagnosed with depression ≥ 4 week duration as measured by CSDD ≥ 8
• Written, informed consent provided by the participant (if they have capacity) or assent (if they do not have capacity) and a written proxy informed consent from a legally authorized representative empowered to make health-related decisions for the potential study participant

Exclusion Criteria:

• The patient is contra-indicated to study drugs of pain treatment, in another trial, or had no carer.
• Participants are ineligible if they are clinical critical (e.g. suicide risk)
• Clinician responsible for care, or study clinician considers that the patient suffers from any physical condition, which would make participation in the trial distressing or likely to increase suffering
• Advanced severe medical disease/disorder with expected survival less than 6 months or that could interfere with participation
• Psychosis or other severe mental disorder prior to dementia diagnosis
• Severe aggression (≥8) on item 3 of the NPI subscale, with aggression as the predominant symptom
• Schizophrenia, schizoaffective disorder and bipolar disorder
• Uncontrolled epilepsy
• Severe liver impairment
• Renal failure
• Severe injury or anaemia (Hb < 8.5 mmol/l), comatose state, current enrolment in another experimental protocol
• Known allergy or adverse reaction to paracetamol or buprenorphine transdermal patch
• Advanced severe medical disease with expected survival of less than six months, severe psychiatric or neurological disorder.
• Patients with diseases that make it impossible to follow the research schedule are excluded