To investigate the specific effect of insomnia
on neuropsychological functioning
in patients with very complex chronic pain
Individuals with insomnia
disorder or chronic pain
often experience cognitive deficits, with both conditions appearing to correlate with impairments in neuropsychological functions. As insomnia
often occurs comorbid with chronic pain
, distinguishing the differential effects of these two syndromes on an individual’s neuropsychological functioning
can be challenging. Comorbid depressive symptoms in these individuals, which may also affect cognitive function, may further obscure the associations between chronic pain
, and the neuropsychological profile.
The neuropsychological function of 22 individuals with very complex chronic pain
was assessed using specialized tests examining aspects of memory
and executive functioning. The severity of insomnia
, depression, and anxiety was measured using questionnaires, and pain levels were assessed using a visual analog scale. Pain medications were transformed to the morphine-equivalent daily dose.
severity was found to predict memory
function, accounting for 32.4% of the variance: A 1 SD increase in insomnia
severity decreased memory
function by 0.57 SD. The negative correlation between insomnia
was significant even after controlling for pain level, morphine-equivalent daily dose, and comorbid levels of anxiety and depression.
severity independently predicted memory
function in patients with very complex chronic pain
, even after controlling for other factors known to impair cognitive function. Insomnia
may possibly explain some of the cognitive impairments related to chronic pain
; thus, screening for, and treating, sleep disturbances may be a central aspect of chronic pain