Memory impairment in chronic pain patients and the related neuropsychological mechanisms: a review

Objective: This study provides a comprehensive review of the literature on memory impairment and the potential effective factors in patients with chronic pain. Methods: A literature search of databases PubMed, EMBASE, SpringerLink, and PsycINFO until September 2012 was conducted using the keywords 'memory' and 'chronic pain'. The study emphasises on publications over the past 20 years. Results: Memory impairment in chronic pain patients is substantial, but the aspects of memory (e. g. working memory, long-term memory, and autobiographical memory) in chronic pain patients and the potentially related factors (e. g. age, level of education, pain conditions, emotion, neural network, and use of analgesics) are modest. Memory impairment is interpreted with the attention-narrowing hypothesis and the capacity-reduction hypothesis. Conclusions: The currently available data and theory have explained memory impairment in chronic pain patients, but many controversies remain. Future research should focus on the subclinical characteristics of chronic pain, enlarging the sample size, and emphasise on the experimental intervention method and the cognitive neuroscience method.