Patients’ perceptions of stress and sleep quality are both linked to their sense of cognitive difficulties and depression, and focusing on these perceptions may be a way of treating depressive symptoms in multiple sclerosis (MS), a study reports.
The research, “Perceived cognitive deficits and depressive symptoms in patients with multiple sclerosis: Perceived stress and sleep quality as mediators,” appeared in the journal Multiple Sclerosis and Related Disorders.
The prevalence of clinically significant depression is higher in MS patients than in the general population or in patients with other chronic illnesses. A combination of individual circumstances, predisposing factors and the nature of MS and its progression likely contributes to depression in these patients, scientists believe.
Cognitive deficits — including difficulties with attention and memory — are also common, and research has shown a link between these deficits and depression in MS. This is true for cognitive problems measured through objective tests, and those defined through questionnaires and other tests of patient perceptions.
“[A] stronger association exists between patient-rated perceived cognitive deficits and depression, than objective cognitive deficits,” the study notes, adding that patients with a positive appraisal of their cognitive performance show less depressive symptoms, while those with a poorer sense of cognitive abilities — including those who underestimated their abilities — exhibit greater depressive symptoms and sleep difficulties.
Negative consequences derived from stress also depend on how it is perceived. MS patients experience distress soon after disease onset due to its symptoms, its impact on daily activities and a possibility uncertain prognosis, which also increase the risk for depression.
Sleep impairments have been reported by nearly 50% of MS patients — again, a higher incidence than in the general population. Poor sleep quality has been associated with both depression and perceived cognitive deficits in these patients.
A total of 77 MS patients (mean age 51, age range 30–75), 64 of whom were women, were recruited from an outpatient, university-based MS Clinic. They had a mean education level of nearly 15 years; 74 (96.1%) were white, 2 were multiracial (2.6%), and one was black (1.3%). This patient group was comparable, in sex and age, to the U.S. national MS population, the researchers noted.
Patients completed the Perceived Deficits Questionnaire (PDQ), a self-reported 20-item measure of skills that include attention, memory and planning ability.
Sleep was assessed using the Pittsburgh Sleep Quality Index (PSQI), a self-reporting tool of sleep quality in the previous month that looks at subjective sleep qualities, sleep latency (how long it takes to fall asleep), duration, efficiency and disturbances, as well as use of medications and sense of daytime dysfunction. Stress was self-reported using the 10-item Perceived Stress Scale (PSS), and feelings of depression using the 20-item questionnaire called the Center for Epidemiological Studies Depression Scale – Revised (CESD-R).
Higher levels of perceived cognitive deficits were associated with poorer sleep quality and greater perceived stress, both of which related to higher levels of depressive symptoms.
“Our primary hypotheses, that the association between perceived cognitive deficits and depressive symptoms would be mediated by poor sleep quality and higher levels of perceived stress, were supported,” the researchers wrote.
MS patients beginning to experience cognitive difficulties, the team suggested, are likely to have heightened perception of stress and — consequently — poorer sleep or more easily disrupted sleep. All these, the researchers said, can affect mood.
“Our study has important clinical implications for identifying, intervening, and treating patients diagnosed with MS who may be at risk for depression,” they added.
“Perceived stress and sleep quality are potentially modifiable factors, perhaps serving as a target for future treatment, to buffer risk of MS patients developing depression.”