Background: Brain areas that are involved in cognition and mood also play a role in pain processing. Objective: The goal of the present study was to examine the relationship between chronic pain and cognition [executive functions (EF) and memory], while controlling for mood, in cognitively intact older persons and in patients with Alzheimer’s disease (AD). Methods: Two groups of subjects participated: 20 older persons without dementia and 19 patients in an early stage of probable AD who suffered from arthrosis/arthritis. Pain intensity and pain affect were assessed by the Colored Analogue Scale for Pain Intensity and for Pain Affect, the Faces Pain Scale (FPS) and the Number of Words Chosen-Affective (NWC-A). Level of depression and anxiety were evaluated by questionnaires. EF and memory were assessed by neuropsychological tests. Results: The results show that significant correlations between specific cognitive functions, pain intensity and pain affect were lacking in the cognitively intact older persons. Cognition, in particular memory, appeared to be related to depressive symptoms. In contrast, a significant positive correlation was observed between EF, pain intensity and pain affect measured by the FPS in the AD group. Conclusions: Although older persons with depression were excluded, in studies on pain and cognition one should control for the presence of depressive symptoms in older persons with and without dementia.

In patients with dementia, undertreatment of pain, irrespective of its aetiology, is widely recognized; the risk for undertreatment increases with the severity of dementia. We argue, however, that central neuropathic pain is by far the most undertreated type of pain in patients with dementia. Central pain is a type of neuropathic pain that is known to occur in stroke patients and is caused by white matter lesions. Although white matter lesions are also a neuropathological hallmark of dementia, central neuropathic pain has hardly been described in dementia. Therefore, the goal of this review was to address assessment and management of pain, with particular emphasis on central neuropathic pain, in moderate to severe dementia. Concerning pain assessment, the findings of this review suggest that self-report pain rating scales, in particular the Verbal Rating Scale, the Horizontal Visual Analogue Scale and the Faces Pain Scale can be administered to patients in a more advanced stage of dementia. For those who are no longer able to communicate pain, pain observation scales are most appropriate. Self-report and pain observation should be combined, if possible. For an overview of assessment tools to measure pain with older people unable to verbally communicate, we refer readers to the City of Hope Pain and Palliative Care Resource Center ( http://prc.coh.org/PAIN-NOA.htm ). The review further highlights that behavioural disturbances, e.g. agitation and physical inactivity, as well as autonomic responses, e.g. an increase in blood pressure and heart rate, may contribute to a more reliable assessment of pain. With respect to central neuropathic pain in particular, assessment of sensory abilities (touch, pinprick, temperature and vibration), mood (e.g. anxiety) and determination of the presence of a Babinsky reflex, accelerated tendon reflexes, and spasticity may contribute to reliable assessment. Management of pain, not of a central origin, starts with paracetamol (acetaminophen), which, together with opioids, is the most frequently prescribed analgesic drug in dementia. Non-steroidal anti-inflammatory drugs are hardly prescribed in a residential setting. Some authors advise starting treatment with a low dose of opioids. Antidepressants and antiepileptic drugs appear to have a positive effect on central neuropathic pain. In the review, advantages and disadvantages of amitriptyline, carbamazepine, lamotrigine, gabapentin and pregabalin are discussed; a negative effect of these drugs on liver and kidney functions, as well as on cognitive functions in patients who already suffer from cognitive impairment is highlighted. Next to pharmacotherapy, non-pharmacological treatment strategies such as transcutaneous electrical nerve stimulation may be effective as long as afferent pathways transmitting the electrical stimulus are still intact.

Undertreatment of pain in dementia seems to be independent of global cognitive functioning. The use of observational scales, to increase the awareness of other signs of pain, e.g. physical inactivity and behavioural disturbances, is recommended. Even if there is no obvious cause for behavioural disturbances, treatment with relatively mild pain medication should be considered.

As VaD patients may experience greater pain than controls, it is essential for prescribers to be aware of the presence of this neuropathology if these patients are to receive adequate treatment.