Neurodegenerative properties of chronic pain: cognitive decline in patients with chronic pancreatitis

Abstract

Chronic pain has been associated with impaired cognitive function. We examined cognitive performance in patients with severe chronic pancreatitis pain. We explored the following factors for their contribution to observed cognitive deficits: pain duration, comorbidity (depression, sleep disturbance), use of opioids, and premorbid alcohol abuse. The cognitive profiles of 16 patients with severe pain due to chronic pancreatitis were determined using an extensive neuropsychological test battery. Data from three cognitive domains (psychomotor performance, memory, executive functions) were compared to data from healthy controls matched for age, gender and education. Multivariate multilevel analysis of the data showed decreased test scores in patients with chronic pancreatitis pain in different cognitive domains. Psychomotor performance and executive functions showed the most prominent decline. Interestingly, pain duration appeared to be the strongest predictor for observed cognitive decline. Depressive symptoms, sleep disturbance, opioid use and history of alcohol abuse provided additional explanations for the observed cognitive decline in some of the tests, but to a lesser extent than pain duration. The negative effect of pain duration on cognitive performance is compatible with the theory of neurodegenerative properties of chronic pain. Therefore, early and effective therapeutic interventions might reduce or prevent decline in cognitive performance, thereby improving outcomes and quality of life in these patients.

Figure 1. Pain duration dependent decrease in cognitive performance.

The figure visualized the pain duration dependent decrease in cognitive performance. Test scores are depicted (ordinate) versus duration of pain in years (abscissa). Only the scores on those nine tests with p≤0.05, explaining test scores with predictors ‘pain duration’ are given (see Table 4 lower panel, model 4: ‘pain duration’). The mean of the scores of the controls (with pain duration zero) on each of the nine tests was taken as 100%. For those test where an increase in test score indicated a decrease in performance, the inverse of the raw scores was taken. The percentage of the test scores of each individual subjects was calculated. The mean and SE of all these percentages (so of all subjects on all nine tests) are shown. For each point the number of subjects is indicated. Remarkable is that the patient that had pain duration of 11 years had a mean test score on the nine tests comparable to the controls. This patient was a young patient of only 29 years old.