A particular effect of sleep, but not pain or depression, on the blood-oxygen-level dependent response during working memory tasks in patients with chronic pain

Abstract

BackgroundPatients with chronic pain (CP) are often reported to have deficits in working memory. Pain impairs working memory, but so do depression and sleep problems, which are also common in CP. Depression has been linked to changes in brain activity in CP during working memory tasks, but the effect of sleep problems on working memory performance and brain activity remains to be investigated.MethodsFifteen CP patients and 17 age-, sex-, and education-matched controls underwent blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging at 3T while performing block design 0-back, 2-back, and paced visual serial addition test paradigms. Subjects also reported their level of pain (Brief Pain Inventory), depression (Beck Depression Inventory II), and sleep problems (Pittsburgh Sleep Quality Index) and were tested outside the scanner with neuropsychological tests of working memory.ResultsThe CP group reported significantly higher levels of pain, depression, and sleep problems. No significant performance difference was found on the neuropsychological tests in or outside the scanner between the two groups. There were no correlations between level of pain, depression, and sleep problems or between these and the neuropsychological test scores. CP patients exhibited significantly less brain activation and deactivation than controls in parietal and frontal lobes, which are the brain areas that normally show activation and deactivation during working memory tasks. Sleep problems independently and significantly modulated the BOLD response to the complex working memory tasks and were associated with decreased brain activation in task-positive regions and decreased deactivation in the default mode network in the CP group compared to the control group. The pain and depression scores covaried with working memory activation.DiscussionSleep problems in CP patients had a significant impact on the BOLD response during working memory tasks, independent of pain level and depression, even when performance was shown not to be significantly affected.

The Effect of Insomnia on Neuropsychological Functioning in Patients with Comorbid Symptoms of Pain, Fatigue, and Mood Disorders

“…A recent study, using fMRI, found that although there were no differences in WM performance between the groups, insomniacs showed abnormalities in neural function, both in terms of reduced activation of task-related regions and the reduced ability to adjust activation with increasing task difficulty ( Drummond et al, 2013 ). A similar pattern has also been found among chronic pain patients, where sleep disturbances had a stronger effect than both pain and depression on the modulation of neural activity ( Elvemo et al, 2015 ). Such findings might suggest that cognitive deficiencies in insomnia are related to alterations in neural activity, rather than just being an epiphenomena of excessive sleepiness.…”

“…Studies in this field of research are also characterized by small sample sizes ( N ≤ 25) ( Drummond et al, 2013 ; Elvemo et al, 2015 ; for a meta-analysis see Fortier-Brochu et al, 2012 ). This means that only very large effects would be statistical significant ( Button et al, 2013 ).The studies that find impairments in working memory report subtle, mild, or moderate effects ( Altena, Van Der Verf, Strijers, & Van Someren, 2008 ; Fortier-Brochu & Morin, 2014 ; Shekleton et al, 2010 ).…”

“…Research examining the effect of insomnia on neuropsychological functioning has often used healthy control groups. The findings have been somewhat inconsistent ( Drummond et al, 2013 ; Elvemo, Landrø, Borchgrevink, & Håberg, 2015 ; Fang, Huang, Yang, & Tsai, 2008 ; Fernandez-Mendoza et al, 2010 ; Fortier-Brochu & Morin, 2014 ; Fulda & Shulz, 2001 ; Goldman-Mellor et al, 2015 ; Orff, Drummond, Nowakowski, & Perlis, 2007 ; Shekleton et al, 2014 ; Shekleton, Rogers, & Rajaratnam, 2010 ; Vignola, Lamoureux, Bastien, & Morin, 2000 ), possibly due to methodological issues related to sample size, diagnostic criteria, the extent to which they have accounted for comorbidities and medications. A recent meta-analysis did, however, find evidence of significant impairments in working memory (WM) ( Fortier-Brochu, Beaulieu-Bonneau, Ivers, & Morin, 2012 ).…”

Impaired psychomotor ability and attention in patients with persistent pain: a cross-sectional comparative study

“… 51 This is interesting because there are factors coexisting with chronic pain, such as poor sleep, depression, and anxiety which can also affect cognitive performance. Alterations in brain activation and interference with attention processes after sleep deprivation have been found in earlier studies 52 , 53 and therefore measures of disturbed sleep should be taken into account in future research.…”

Cognitive deficits associated with impaired awareness of hypoglycaemia in type 1 diabetes

“…Optimal cognitive function depends on interaction within networks of brain regions. For learning, memory, and pattern separation abilities, the most central structure for normal functioning is the hippocampus [ 25 , 26 ], while executive functions, working memory and information processing speed depend on frontal and parietal cortices and their connectivity [ 27 , 28 ]. The intention was to test cognitive abilities that depend on brain regions susceptible to damage during hypoglycaemia [ 11 , 21 ] and cognitive abilities that are recognised to be impaired in patients with type 1 diabetes [ 4 , 5 ].…”