Study links MS to greater long-term memory loss over time
Earlier detection may enable interventions targeting symptom progression
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Increased memory loss over longer periods is greater in people with multiple sclerosis than in healthy adults, according to a study. (Image from iStock)
- People with multiple sclerosis experience accelerated long-term forgetting.
- This long-term memory decline correlates with subjective memory complaints.
- Implementing extended-delay memory testing may improve early detection.
Increased memory loss over longer periods, known as accelerated long-term forgetting (ALF), is greater in people with multiple sclerosis (MS) than in healthy adults, a study found.
Although people with MS performed similarly to healthy controls on short-term memory tests, they remembered significantly less information seven days later, suggesting that longer-term memory testing may uncover difficulties missed by routine assessments.
“ALF measures may offer an approach for earlier detection and enable interventions that may positively influence symptom progression,” researchers wrote.
The study, “Accelerated long-term forgetting as an objective marker of subjective memory impairment in multiple sclerosis,” was published in Neurological Research and Practice.
Memory problems common in MS patients
MS is characterized by the immune system mistakenly attacking and damaging the myelin sheath, a protective layer around nerve fibers that helps them communicate more efficiently. This leads to symptoms such as movement problems, fatigue, and cognitive changes.
Memory problems are common in people with MS, including ALF, when people initially learn and recall information normally but experience greater memory loss over longer periods. In the context of ALF, verbal memory (learning, retaining, and retrieving words or storylines) may be particularly affected in MS.
To learn more about ALF in a diverse group of MS patients and whether it is associated with patient-reported outcomes, researchers in Germany conducted a study in 62 people with MS and 65 healthy controls. Participants had a mean age of 37 years, and about three-quarters were women.
MS patients remembered significantly less after 7 days
On average, 56 participants with MS experienced their last relapse about three years before enrolling in the study. Their last MRI, available for 49 patients, had been performed close to 20 months prior. The number of patients with a low MS lesion burden (less than 10 lesions) was similar to those with a high burden (at least 20 lesions).
Verbal memory was assessed using two standard tests. The Rey Auditory Verbal Learning Test (RAVLT) consists of learning 15 words and recalling them after an interfering task. The Logical Memory test from the Wechsler Memory Scale-IV (WMS-IV) requires participants to recall details from two short stories. For both tests, memory was assessed immediately, after 30 minutes, and after seven days.
Participants with MS showed significantly more ALF than healthy controls on both tests. Although the two groups performed similarly immediately after learning and after 30 minutes, people with MS remembered significantly less after seven days. These effects remained significant after adjusting for patients’ performance after 30 minutes.
“The long-delay recall extensions of the RAVLT and the WMS-IV Logical Memory subtest appear suitable for identifying memory impairments that remain undetected in short-delay recall assessments,” the scientists wrote.
In contrast, objective measures of cognition and information-processing speed, assessed using the Montreal Cognitive Assessment and the Symbol Digit Modalities Test, respectively, did not differ significantly between the groups.
[Establishing sensitive methods to detect ALF] may provide access to therapeutic interventions for memory impairment at an early stage, thereby positively influencing the course of the disease.
People with MS also reported significantly more fatigue, poorer sleep quality, and more memory difficulties than healthy controls.
Further analysis demonstrated that among people with MS, more severe fatigue was associated with poorer performance on the RALVT test. Greater difficulty remembering stories was also associated with more severe fatigue, sleep problems, subjective memory complaints, greater disability, and older age. No similar associations were found among the controls.
The researchers also assessed whether the combined ALF score, calculated as the mean of the RAVLT and the WMS scores, could help identify people with MS who reported memory problems, which was measured by asking the participants whether they had recently perceived themselves as more forgetful. The test showed moderate accuracy, with an area under the curve (AUC) of 0.735. AUC measures how well a test distinguishes between people with and without a particular condition, with 1 representing perfect discrimination.
At a cutoff of 0.71, the combined ALF score correctly identified 72.7% of people with subjective memory impairment and correctly ruled it out in about 72.5% of those without it.
According to the researchers, “ALF testing may provide an objective complement to subjective memory complaints and fatigue-related difficulties.” They also noted that establishing sensitive methods to detect ALF “may provide access to therapeutic interventions for memory impairment at an early stage, thereby positively influencing the course of the disease.”
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