Efficacy of Pain Treatment on 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, cu…