We have already spoken on several occasions of the possible cognitive difficulties in multiple sclerosis which may concern the the memory and executive functions. We have also seen how these deficits, when present, also tend to associate difficulties in everyday life, as well as to driving skills and maintenance of employment; we have also seen how the presence of such cognitive problems can predict disease progress and conversion from relapsing remitting to progressive.
With a research published in 2019, Pitteri and collaborators they sought to shed light on the relationship between memory and executive functions in the context of multiple sclerosis. In their study, the researchers set two goals:
- Investigate the role of executive functions in verbal learning deficits that frequently occur in people with multiple sclerosis
- Understand this relationship in the light of brain changes (cortical thickness in regions related to memory and regions related to executive functions).
To achieve the goals just described, a group of patients underwent verbal memory tests extracted from Short and Repeatable Battery of Neuropsychological Tests Rao's Selective Reminding Test, a test similar to Buschke-Fuld's Verbal Supra-Span Learning (here a short description).
The same people have also been subjected to and test for executive functions: the Stroop Test, the Alternate Fluence Test and the Modified Five Point Test (all tests are described here).
In addition, for each patient, through magnetic resonance imaging, they were look for brain changes both gray matter and white matter believed to be linked to memory and executive function deficits.
Compared to executive functions, the Alternate Fluidity Test was significantly correlated to the scores in the memory test, going so far as to explain a share of variance between 38% and 42% of verbal mnemonic tests.
With respect to cortical thickness, the alterations of the right medial frontal cortex, of the upper right frontal gyrus, of the right and left hippocampus, of the right and left orbital-frontal cortex and of the right frontal pole explained a share of variance between 45% and 52% of performance in verbal memory tasks.
Verbal learning skills therefore seem associated with deficits in executive functions and frontal and temporal brain alterations.
The data emerged in this research suggest the possibility that executive functions, in particular cognitive flexibility, influence mnesic abilities, finding additional data to support this hypothesis in the association between cerebral alterations in the front-temporal zone and verbal learning deficit.
It is important to underline that the data coming from this research are exclusively correlational and do not allow to reach conclusions about the cause-effect links. However, if the conclusions reached by the authors (perhaps too quickly) were confirmed by other research, it would make sense to assume that, in the presence of mnemonic deficits, rehabilitation should not be based exclusively on the memory itself but perhaps it would be appropriate to integrate it with a work also aimed at executive functions.
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