Switching attention deficits in post-stroke individuals with different aphasia types

Abstract

Background: Previous studies have shown that individuals with aphasia have impairments in switching attention compared to healthy controls. However, there is insufficient information about the characteristics of switching attention within one task and whether attention deficits vary depending on aphasia type and lesion location. We aimed to address these knowledge gaps by investigating characteristics of switching attention within one type of task in participants with different types of aphasia and distinct lesion sites.

Method: Forty individuals with post-stroke aphasia (20 with non-fluent aphasia and frontal lobe damage, and 20 with fluent aphasia and temporal lobe damage) and 20 neurologically healthy age-matched individuals performed an attention switching task. They listened to sequences of high-pitched and low-pitched tones that were presented to them one by one, tallied them separately, and, at the end of each sequence, had to say how many high- and low-pitched tones they had heard.

Results: Participants with aphasia performed significantly worse on the task compared to healthy controls, and the performance of two aphasia groups also differed. Specifically, individuals with both aphasia types made more errors than healthy individuals, and the participants with non-fluent aphasia responded more slowly than controls, while reaction times of the participants with fluent aphasia did not differ significantly from those of controls. Also, the two groups of participants with aphasia differed significantly in accuracy, with individuals in the non-fluent group making more errors.

Conclusions: The data demonstrated that people with different types of aphasia have distinct impairments in switching attention. Since cognitive deficits impact language performance, this information is important for differentially addressing their language problems and selecting more specific and optimal rehabilitation programs that target different underlying mechanisms.

Keywords: Aphasia; Fluent aphasia; attention; non-fluent aphasia; switching attention.

Figure 1.

Schematic representation of the experimental switching attention task.

Figure 2.

Boxplots for correct responses and reaction times. The box represents the interquartile range, with the central line marking the median, and the cross representing mean. The whiskers denote the largest/smallest values within 1.5 times the interquartile range above/below the 75th/25th percentile. Values falling outside of that range are shown as points. The asterisk marks significant differences between groups according to the Mann–Whitney U-test with controlled familywise error. Reaction times are measured in milliseconds, and accuracy is the number of correct responses.

Figure 3.

Confidence Interval analysis for accuracy and reaction times. The gray bar represents a 95% Confidence Interval around the mean of the control group, with the red central line marking the mean. The red dots represent participants with non-fluent aphasia and blue dots represent participants with fluent aphasia. Accordingly, dots to the left of the confidence interval (gray bar) represent performance below the mean of the control group (less accurate and slower). Note, that the x-axis is reversed for the reaction times.