The verbal, non-verbal and structural bases of functional communication abilities in aphasia

Abstract

The ability to communicate, functionally, after stroke or other types of acquired brain injury is crucial for the person involved and the people around them. Accordingly, assessment of functional communication is increasingly used in large-scale randomized controlled trials as the primary outcome measure. Despite the importance of functional communication abilities to everyday life and their centrality to the measured efficacy of aphasia interventions, there is little knowledge about how commonly-used measures of functional communication relate to each other, whether they capture and grade the full range of patients’ remaining communication skills and how these abilities relate to the patients’ verbal and nonverbal impairments as well as the underpinning lesions. Going beyond language-only factors is essential given that nonverbal abilities can play a crucial role in an individual’s ability to communicate effectively. The current study, based on a large sample of patients covering the full range and types of post-stroke aphasia, addressed these important, open questions. The investigation combined data from three established measures of functional communication with a thorough assessment of verbal and nonverbal cognition as well as structural neuroimaging. The key findings included: (a) due to floor or ceiling effects, the full range of patients’ functional communication abilities was not captured by a single assessment alone, limiting the utility of adopting individual tests as outcome measures in randomized controlled trials; (b) phonological abilities were most strongly related to all measures of functional communication; and (c) nonverbal cognition was particularly crucial when language production was relatively impaired and other modes of communication were allowed, when patients rated their own communication abilities, and when carers rated patients’ basic communication abilities. Finally, in addition to lesion load being significantly related to all measures of functional communication, lesion analyses showed partially overlapping clusters in language regions for the functional communication tests. Moreover, mirroring the findings from the regression analyses, additional regions previously associated with nonverbal cognition emerged for the Scenario Test and for the Patient Communication Outcome after Stroke rating scale. In conclusion, our findings elucidated the cognitive and neural bases of functional communication abilities, which may inform future clinical practice regarding assessments and therapy. In particular, it is necessary to use more than one measure to capture the full range and multifaceted nature of patients’ functional communication abilities and a therapeutic focus on nonverbal cognition might have positive effects on this important aspect of activity and participation.

Recovery after stroke: the severely impaired are a distinct group

“…Performance in several of these tests may even be combined to more faithfully capture the full range of individual patients’ motor abilities and decrease ceiling effects. Such a strategy was already shown to be effective in the case of aphasia,37 where some clinical tests appear to be affected by ceiling effects as well 38. Similarly, it may be beneficial to extend the granularity and dynamic range of measures by adopting dynamic staircase methodologies.…”

Estimating the cost and value of functional changes in communication ability following telepractice treatment for aphasia

“…We do not draw a clear conclusion that comprehension skills are more likely to recover than expression. In particular, recovery of functional communication depends upon their language impairment as well as disruption in cognitive processes as well as verbal and non-verbal abilities [24]. Regardless, the long-term improvements translate into improved quality of life and greater engagement and participation in society.…”

“…Second, NOMS are clinician reported measures of functional communication. Some believe the that best measures of functional communication emerge from the perspective of the individuals with the communication disorder, rather than the treatment provider [24]. Consequently, differences in how PWA and clinicians report functional communication ability should be considered.…”

Mapping language and non-language cognitive deficits in post-stroke anomic aphasia

“…This has resulted in some distinct brain-behaviour relationships for various language domains, however studies have not been able to converge on a consistent lesion correlate of higher-level executive functions (Mirman and Thye, 2018), either because non-language assessments were not included (Kummerer et al, 2013; Mirman et al, 2015) or were only included in a limited scope (Butler et al, 2014;Halai et al, 2017;Tochadse et al, 2018; though see Lacey et al, 2017). More recently, the neural correlates of non-language cognitive domains in aphasia have been explored by Schumacher et al, (2019Schumacher et al, ( , 2020 and Alyahya et al, (2020), whose findings are discussed in more detail below.…”

“…A better understanding of language processing in the context of other domain-general cognitive functions is important for clinical management and rehabilitation. In fact, a series of aphasia therapy studies emphasise that cognitive abilities, particularly executive functions and verbal short-term memory, play an important role in driving recovery outcomes (Fillingham, Sage and Lambon Ralph, 2005a, 2005b, 2006; Conroy, Sage and Lambon Ralph, 2009; Mirman et al, 2015; Lambon Ralph et al, 2010; Yeung and Law, 2010; Snell, Sage and Lambon Ralph, 2010, Sage, Snell and Lambon Ralph, 2011; Dignam et al, 2017; Lacey et al, 2017; Schumacher et al, 2020).…”