Authors' Response

Abstract

We appreciate the opportunity to respond to the letter from Giannopoulos et al. concerning our work about neuropathic pain and cognitive impairment. We would like to thank the letter's authors for their contribution to this exciting topic. Our study analyzed the baseline data from a prospective study of gabapentin and, after controlling for different possible confounding factors (including symptoms of depression and anxiety, among others), found a higher prevalence of some degree of cognitive impairment (using the Mini-Mental State Examination) in comparison with the general population. Due to the possible limitations of the study, particularly the cross-sectional analysis of data, our conclusions noted that the prevalence of cognitive impairment in patients with neuropathic pain increases with age, presence of symptoms of anxiety or depression, obesity, and present pain intensity. The data also underscored the need for epidemiological studies, however, especially studies designed to characterize and quantify more accurately and with no bias the relationship between cognitive impairment and neuropathic pain, particularly as regards prevalence and incidence, which may support the findings reported in the study. Also, we concluded that it would be convenient that such research were designed in such a way as to be able to establish if the known association between general pain and cognitive impairment is changed when pain is of a neuropathic origin. Hence, we believe these conclusions are aligned with what Giannopoulos et al. comment on in their letter. It is not linking pain with cognitive impairment, but it is highlighting the need for exploring more deeply the relationship between pain and cognitive function, which should be of interest to the scientific community. On the other hand, and as mentioned, due to the study's design, we cannot know if the cognitive dysfunction identified is reversible or not. That is one of the reasons why we suggest the need for epidemiological studies. To better understand the relationship between pain (particularly neuropathic) and cognitive function, studies must control the possible confounding effects caused by anxiety, depression, poor level of pain control, drug effect itself, and even the dosage used of the analgesics. This could not be evaluated in our work as it was a cross-sectional analysis only, performed before gabapentin was administered to patients. Giannopoulos et al. comment in their letter that it would be interesting to see if similar results are noted in future studies using selective serotonin reuptake inhibitors for pain control, which have fewer side effects on cognition and may reduce the anxiety/depression associated with neuropathic pain. While we completely agree with this assertion, we also believe that the possible connection between pain and cognitive impairment should be explored independently. Cognitive Impairment in Patients with Neuropathic PainJournal of Pain and Symptom ManagementVol. 34Issue 1PreviewWe read with great interest the article by Povedano et al.1 concerning the cognitive function impairment of patients with neuropathic pain under standard conditions of care. The authors collected data in a prospective multicenter study that evaluated cognitive function by measuring Mini-Mental State Examination scores in 1,519 patients treated with gabapentin for either neuropathic or mixed neuropathic and nociceptive pain. The investigators presented data showing that the prevalence of cognitive impairment was substantially higher (almost twofold) in patients with neuropathic pain than those with mixed pain and the general population. Full-Text PDF Open Archive