Clinical review Recent developments in pain in dementia

Epidemiological studies show that, worldwide, the number of people aged over 65 will increase substantially in the next decades and that a considerable proportion of this population will develop dementia. Ample evidence shows that ageing is associated with a high rate of painful conditions, irrespective of cognitive status. The number of patients with dementia who will experience painful conditions is therefore likely to increase. A key question relates to whether and how patients with dementia perceive pain. Patients with dementia may express their pain in ways that are quite different from those of elderly people without dementia. Particularly in the more severe stages of dementia, therefore, the complexity and consequent (frequent) inadequacy of pain assessment leads to the undertreatment of pain. The most commonly used pain assessment instruments seem to be selected primarily according to the communicative capacity of the patient (self report pain rating scales for communicative patients and observation scales for non-communicative patients) instead of according to two main aspects of pain—the sensory-discriminative and motivational-affective aspects. In particular, the motivational-affective aspects of pain are assessed by observation scales, which should therefore be applied to every patient, irrespective of ability to communicate. Distinction between the sensory-discriminative and motivationalaffective aspects of pain is of great clinical relevance, as the motivational-affective aspects are particularly likely to reflect pain that needs treatment. Moreover, differentiating between these two aspects of pain in relation to the neuropathology of the various subtypes of dementia provides insight into the basis of the alterations in the pain experiences of elderly people with dementia. Future experimental and clinical studies should not only focus on subtypes of dementia but should go a step further and assess pain in disorders in which pain is already present at a stage without cognitive impairment and during the course of which patients become cognitively impaired.