Executive function and aphasia

Abstract

Executive and cognitive functioning was examined in 25 individuals (aged 41-80 yrs) with aphasia following stroke, 7 nonaphasic individuals (aged 39-76 yrs) with frontal lobe injury, and 25 control participants. Clinical and experimental measures were administered using nonverbal instructions. Tests included the Raven's Coloured Progressive Matrices, Tower of Hanoi (TOH), Porteus Mazes (PM), Judgment of Line Orientation, Western Aphasia Battery, and a new board test of spatial planning, the Errands Test. The aphasic group performed more poorly than the control group on some tests. Performance by all participants was submitted to a factor analysis, from which two factors emerged. The TOH measures loaded together with PM error score, while the PM test age score loaded with the efficiency, strategy, and error scores from the Errands Test. Poorer performance on the TOH-PM factor was predicted by the extent of brain injury and psychomotor slowing. Poorer performance on the Errands-PM factor was predicted by anterior location of the lesion, poorer visuospatial ability, and psychomotor slowing. The Errands-PM factor correlated with functional communication of the aphasic participants (measured by the ASHA-Functional Assessment of Communication Skills). Level of aphasia severity, auditory comprehension, and ideomotor praxis did not account for performance on the cognitive tests. The study results suggest that aphasic individuals may have additional cognitive impairments, including planning and strategy use, and that these deficits can be measured validly using nonverbal measures. Until the cognitive processes of executive functioning are better defined and assessed, batteries of tests may be necessary to predict patients' weaknesses and strengths.