Diedrichs, V.A., Jewell, C., & Harnish, S.M. (2022). A scoping review of the relationship between nonlinguistic cognitive factors and aphasia treatment response. Topics in Language Disorders, 42(3), 212–235.

The purpose of this article was to explore the extent to which nonlinguistic cognitive factors demonstrate a relationship with aphasia treatment outcomes. To that end, we conducted a scoping review to broadly characterize the state of the literature related to this topic. Reporting guidelines from the PRISMA extension for scoping reviews were used to conduct our study, which queried two common databases used in the health science literature, PubMed and Web of Science. Search terms and eligibility criteria are provided. Results are organized by the four nonlinguistic domains of cognition explored across the included studies (i.e., attention, memory, executive functioning, and visuospatial skills). Of 949 unique articles identified from our database searches, 17 articles with 18 distinct studies were included in the final scoping review. Notably, most studies included in the scoping review targeted impairment-based aphasia treatments. Most studies also examined multiple domains of nonlinguistic cognition. A relationship between cognition and poststroke aphasia therapy outcomes was identified in nine of 15 studies addressing executive functioning, four of nine studies examining memory, four of eight studies examining visuospatial skills, and two of five studies exploring attention. The results among included studies were mixed, with few discernible patterns within each of the four cognitive domains, though it appears that the influence of nonlinguistic cognition may depend on the timing (i.e., immediate vs. delayed post-treatment) and type (i.e., trained vs. untrained, generalized) of aphasia therapy outcomes. Future study designs should address maintenance, by including outcome measures at follow-up, and generalization, by including measures of performance on either untrained stimuli or trained stimuli in untrained contexts. Future work should also strive for larger sample sizes, perhaps through collaborations, or prioritize replicability to produce more reliable conclusions.

Diedrichs, V.A., Lundine, J.P., Schwen Blackett, D., Zezinka Durfee, A., Pan, X.J., & Harnish, S.M. (2023). A randomized crossover single-case series comparing blocked versus random treatment for anomia. Neuropsychological Rehabilitation, 33(5), 821-848.

The motor learning literature has demonstrated that blocked practice facilitates better acquisition of motor skills, whereas random practice facilitates retention and transfer. The verbal learning and memory literature offers similar evidence. The purpose of this study was to investigate effects of blocked versus random practice in treatment for anomia. The study used a single site, randomized crossover design, with two replicated experimental phases (two blocked and two random) for each of 10 individuals with anomia. Each phase consisted of a cued picture-naming treatment. Individual treatment and maintenance effects, as well as weighted averages and group effects, were calculated using Tau-U based on the proportion of correctly named probes. Nine of 10 participants demonstrated treatment effects during each of the four phases. Acquisition was comparable for blocked and random practice. Maintenance effects were observed following seven blocked phases of treatment and 12 random phases of treatment across participants. For four of 10 participants the random schedule resulted in better maintenance of trained items. Although further research is needed, the present data suggest that for word retrieval treatment with multiple repetitions of the same items, a random presentation may benefit maintenance of treatment gains.

Harnish, S.M., Diedrichs, V.A., & Bartlett, C. (2023). Early considerations of genetics in aphasia rehabilitation: A narrative review. Aphasiology, 37(6), 835-853.

Background: Early investigations linking language and genetics were focused on the evolution of human communication in populations with developmental speech and language disorders. Recently, studies suggest that genes may also modulate recovery from post-stroke aphasia. Aims: Our goal is to review current literature related to the influence of genetics on post-stroke recovery, and the implications for aphasia rehabilitation. We describe candidate genes implicated by empirical findings and address additional clinical considerations. Main Contribution: We describe existing evidence and mechanisms supporting future investigations into how genetic factors may modulate aphasia recovery and propose that two candidate genes, brain derived neurotrophic factor (BDNF) and apolipoprotein E (APOE), may be important considerations for future research assessing response to aphasia treatment. Evidence suggests that BDNF is important for learning, memory, and neuroplasticity. APOE influences cognitive functioning and memory in older individuals and has also been implicated in neural repair. Moreover, recent data suggest an interaction between specific alleles of the BDNF and APOE genes in influencing episodic memory. Conclusions: Genetic influences on recovery from aphasia have been largely unexplored in the literature despite evidence that genetic factors influence behaviour and recovery from brain injury. As researchers continue to explore prognostic factors that may influence response to aphasia treatment, it is time for genetic factors to be considered as a source of variability. As the field moves in the direction of personalized medicine, eventually allied health professionals may utilize genetic profiles to inform treatment decisions and education for patients and care partners.