Depression, Prednisone Use Linked to Cognitive Problems in Patients

Tasks involving memory can be difficult for people with myasthenia gravis (MG) due to depression and the use of glucocorticosteroids, a study from Brazil found.

The study, “Cognitive performance in patients with Myasthenia Gravis: an association with glucocorticosteroid use and depression,” was published in the journal Dementia & Neuropsychologia.

MG patents primarily show muscular weakness, but recent studies have suggested a connection with cognitive impairments possibly due to factors such as type of treatment and mood disturbances. However, research to date remains unclear, and no study has specifically looked at the Brazilian population with MG.

Aiming to address these knowledge gaps, a team of researchers in Porto Alegre recruited 39 patients (mean age 51, range 18 to 84) with a confirmed MG diagnosis being treated at a neuromuscular disease outpatient clinic between February 2017 and December 2018.

Each was asked to undergo a series of tests designed to evaluate metrics such as demographics, quality of life, depression, daytime sleepiness, motor function, and cognitive performance. Data on MG treatments were collected from patients’ clinical records.

The team first found high prevalence of cognitive difficulties, as assessed by the Montreal Cognitive Assessment (MoCA) and the Rey Auditory Verbal Learning Test (RAVLT).

In particular, a majority of the patients showed impairments on the immediate (59%) and recent memory (56.4%) portions of the RAVLT. Two-thirds (66.7%) of them showed cognitive difficulties on the MoCA test.

The study also found that 23.1% of patients had scores suggesting excessive daytime sleepiness, as measured by the self-reported Epworth Sleepiness Scale, and 41% had scores suggesting depression, as measured by the Beck Depression Inventory. Beck scores for eight of these patients (20.5%) were within the range of moderate to severe depression, and three (7.7%) in the severe depression range.

Higher (better) cognitive test scores were significantly linked with higher levels of education among patients, the study reported.

Data also showed a correlation between age and the memory tests using RAVLT, with younger MG patients having better scores than older ones.

While quality of life measures did not associate with cognitive ability, the team found a correlation between life quality and the severity of MG motor symptoms, as measured by the Myasthenia Gravis Composite Scale (MGCS). Patients reporting a poorer quality of life were those with more severe motor impairments.

MGCS scores also linked with the short-term memory task of the RAVLT, indicating that patients with reduced motor abilities were more likely to have memory problems. Short-term memory did not associate with the presence of thymomas (thymus gland tumors).

Patients diagnosed with depression were significantly more likely to show cognitive difficulties as measured by MoCA and two other assessments, the Semantic Verbal Fluency and the Phonemic Verbal Fluency tests, the investigators found.

“In our sample, there was a significant prevalence ratio of depression in participants who showed cognitive impairment on screening tests, where verbal fluency and memory are concerned,” the researchers wrote.

The study also looked at treatments, reporting that 92.3% of patients used anticholinesterase inhibitors and 59% used glucocorticosteroids like prednisone. Most patients used two or more treatment methods.

Prednisone use was associated with a greater risk of depression, and poorer scores on the short-term memory task of the RAVLT.

“The risk of memory impairment should be considered before starting treatment with GC [glucocorticosteroids] and in monitoring patients with MG,” the scientists wrote.

According to the team, the study’s limitations included it being conducted at a specialized clinic, as its participants may have  more severe disease.