Table 1.
Predictors of aphasia recovery
| Predictor | Evidence | Reference | ||
|---|---|---|---|---|
| Biographical predictors | ||||
| Age | Younger age is associated with greater treated recovery. | Lendrem et al. [46] (1988), Marshall et al. [47] (1982), van de Sandt-Koenderman et al. [50] (2008), Pickersgill et al. [49] (1983), Nakagawa et al. [48] (2019), Johnson et al. [51] (forthcoming) | ||
| Failed to find a relationship between age and treated recovery. | Code et al. [52] (2010), Persad et al. [54] (2013), Seniów et al. [55] (2009), Nardo et al. [53] (2017) | |||
| Sex | Observed better spontaneous recovery of language function in females. | Basso et al. [59] (1992), Pizzamiglio et al. [60] (1985), Ali et al. [29] (2021) | ||
| Observed better spontaneous recovery of language function in males. | Holland et al. [32] (1989) | |||
| Failed to find a sex-dependent difference in spontaneous recovery. | Godefroy et al. [61] (2002), Inatomi et al. [36] (2008), Lazar et al. [37] (2008), Lendrem et al. [38] (1985), Pedersen et al. [39] (1995), Seniów et al. [55] (2009) | |||
| Handedness | No evidence for the notion that left-handed individuals have greater capacity for spontaneous language recovery. | Lazar et al. [37] (2008), Pedersen et al. [39] (1995) | ||
| Education | Associated with cross-sectional aphasia severity; not spontaneous recovery. | Smith [68] (1971), Lazar et al. [37] (2008), Hillis et al. [65] (2014), Hillis et al. [31] (2018), Ramsey et al. [67] (2017) | ||
| Time post-onset | TPS does not seem to be related to therapy response. | Holland et al. [72] (2017), Nardo et al. [53] (2017), Persad et al. [54] (2013) | ||
| Psychosocial factors | Psychosocial factors may contribute to the likelihood of positive outcomes following therapy, although further research is necessary. | Biel et al. [77] (2017), Worrall et al. [76] (2017), Hilari et al. [74] (2012), Berthier [82] (2021), Mohr et al. [83] (2017) | ||
| Aphasia type | Broca’s aphasia may predict favorable therapy response. | Bakheit et al. [85] (2007) | ||
| Fluent aphasia subtypes predict favorable therapy response. | Jung et al. [86] (2011), Kristinsson et al. [8] (2021) | |||
| Neuropsychological predictors | ||||
| Aphasia severity | Pre-therapy aphasia severity strongly predicts therapy response. | Basso [59] (1992), Nakagawa et al. [48] (2019), Code et al. [52] (2010), Efstratiadou et al. [88] (2018), Persad et al. [54] (2013) | ||
| Stroke severity | Stroke severity predicts therapy response. | Breitenstein et al. [6] (2017) | ||
| Anomia severity | Pre-therapy anomia severity strongly predicts therapy response. | Lambon Ralph et al. [12] (2010), Seniów et al. [55] (2009), Wisenburn et al. [89] (2009), Efstratiadou et al. [88] (2018) | ||
| Cognitive processing | Various baseline cognitive factors are associated with therapy response. | Seniów et al. [55] (2009), Lambon Ralph et al. [12] (2010), Dignam et al. [97] (2017), Fillingham et al. [98] (2006) | ||
| Intelligence | Not related to spontaneous recovery. | David et al. [100] (1984), Ferro et al. [101] (1999) | ||
| Neurobiological predictors | ||||
| Lesion size | Inversely related to spontaneous recovery and frequently treated as a covariate in therapy studies. | Kertesz et al. [108] (1979), Goldenberg et al. [107] (1994), Hope et al. [106] (2013), Maas et al. [109] (2012), Fridriksson[119] (2010), Bonilha et al. [118] (2016), Varkanitsa et al. [121] (2020), Meier et al. [120] (2019) | ||
| Failed to find an independent relationship with spontaneous recovery, and therapy progress | Pedersen et al. [39] (1995), Laska et al. [34] (2001), Lazar et al. [37] (2008), Marcotte et al. [122] (2012), Varkanitsa et al. [121] (2020) | |||
| Leukoaraiosis | Leukoaraiosis predicted longitudinal decline in language function in chronic aphasia. | Basilakos et al. [115] (2019) | ||
| Lesion location | ||||
| Temporo-parietooccipital junction | Lesion associated with poor spontaneous recovery. | Naeser et al. [112] (1987), Hanlon et al. [131] (1999), Goldenberg et al. [107] (1994) | ||
| Lesion to the temporal-occipital junction predicts poor therapy response. | Fridriksson [119] (2010) | |||
| Sparing of the temporoparietal junction predicts positive therapy response. | Parkinson et al. [125] (2009), Bonilha et al. [118] (2016), Fridriksson et al. [11] (2012) | |||
| pSTG | Lesion associated with poor spontaneous recovery. | Selnes et al. [114] (1983), Hillis et al. [31] (2018) | ||
| SMG | Lesion as sociated with poor spontaneous recovery. | Selnes et al. [114] (1983), Kertesz et al. [132] (1993) | ||
| AG | Lesion associated with poor spontaneous recovery. | Kertesz et al. [132] (1993) | ||
| STG | Sparing of the STG predicts positive spontaneous recovery. | Kertesz et al. [132] (1993) | ||
| MTG | Sparing of the MTG predicts positive spontaneous recovery. | Kertesz et al. [132] (1993) | ||
| SLF/AF | Lesion associated with poor spontaneous recovery. | Hillis et al. [31] (2018), Ramsey et al. [67] (2017) | ||
| pMTG | Lesion predicts poor therapy response. | Fridriksson [119] (2010) | ||
| Basal ganglia | Sparing of basal ganglia predicts positive therapy response in cases of relatively large anterior lesions. | Parkinson et al. [125] (2009) | ||
| IFG | Lesion predicts poor response to SFA therapy. | Marcotte et al. [122] (2012) | ||
| Lesion predicts positive response to SE therapy. | Fridriksson et al. [136] (2015) | |||
| MFG | Lesion predicts positive response to SE therapy. | Fridriksson et al. [136] (2015) | ||
| Domain-general ROIs | Integrity of DG regions has been suggested to mediate positive therapy response. | Barbieri et al. [171] (2019) | ||
| Functional activation | ||||
| RH recruitment | May facilitate therapy-induced recovery to a certain degree in case of large lesion. | Barbieri et al. [171] (2019), Raboyeau et al. [159] (2008), Benjamin et al. [172] (2018) | ||
| LH normalization | Normalization of functional activation in language regions is associated with favorable therapy-induced recovery. | Kiran et al. [175] (2015), Thompson et al. [169] (2013), Fridriksson et al. [11] (2012), Johnson et al. [166] (2020), Hallam et al. [165] (2018), Dietz et al. [164] (2018), Richter et al. [168] (2008), Meinzer et al. [170] (2008), Fridriksson et al. [11] (2012), Fridriksson [119] (2010) | ||
| Bilateral recruitment | Bilateral functional activation may facilitate therapy-induced recovery. | van Hees et al. [177] (2014), Fridriksson et al. [173] (2007), Kiran et al. [175] (2015), Fridriksson et al. [174] (2006), Nardo et al. [53] (2017), Thompson et al. [176] (2010), Johnsonn et al. [166] (2020), Menke et al. [180] (2009) | ||
| Domain-general ROIs | DG regions not specific to language may facilitate recovery in some individuals. | Barbieri et al. [171] (2019), Geranmayeh et al. [178] (2017), Brownsett et al. [137] (2014) | ||
| PrCG | Pre-therapy activation predicted response to SFA therapy. | Marcotte et al. [122] (2012) | ||
| Caudate nucleus | Pre-therapy activation predicted response to SFA therapy. | van Hees et al. [177] (2014) | ||
| Functional activation×Lesion location/size | Multiple studies suggest that the association between functional activation, language impairment, and recovery is lesion-dependent. | Skipper-Kallal et al. [185,186] (2017), Griffis et al. [148] (2017), Richter et al. [168] (2008), Blank et al. [183] (2002), Leff et al. [157] (2002), Johnson et al. [166] (2020), Heiss et al. [184] (1999), Abel et al. [161] (2015) | ||
| Functional connectivity | ||||
| Network normalization | Connectivity strength across networks correlates with specific language functions; increased connectivity correlates with spontaneous recovery. | Zhu et al. [189] (2014), Geranmayeh et al. [178] (2017), Brownsett et al. [137] (2014), Siegel et al. [188] (2018), Yang et al. [192] (2016), Balaev et al. [190] (2016), Dijkhuizen et al. [191] (2014), Sandberg [187] (2017) | ||
| Successful response to therapy is characterized by normalization of functional connectivity. | Kiran et al. [175] (2015), Marcotte et al. [196] (2013), van Hees et al. [177] (2014), Sandberg et al. [197] (2015), Gili et al. [195] (2017), Santhanam et al. [198] (2018), Duncan et al. [194] (2016), Duncan et al. [200] (2018), Iorga et al. [201] (2021), Baliki et al. [199] (2018), Woodhead et al. [202] (2017) | |||
| Contralateral connectivity | Larger lesions correlate with increased contralateral connectivity, globally and regionally. | Yourganov et al. [193] (2021) | ||
| LH IFG | SFA therapy induces increased connectivity centered in the IFG. | Kiran et al. [175] (2015) | ||
| RH MTG | Pre-therapy connectivity correlated with response to phonological anomia therapy. | van Hees et al. [177] (2014) | ||
| Structural connectivity | ||||
| LH AF | Disruption of connectivity correlates with poor speech fluency. | Fridriksson et al. [209] (2013), Marchina et al. [210] (2011), Wang et al. [211] (2013), Basilakos et al. [208] (2014) | ||
| LH SLF | Disruption of connectivity correlates with poor naming ability. | Han et al. [212] (2013), Ivanova et al. [213] (2016) | ||
| Network integrity | Integrity of various white matter connections is associated with cross-sectional language function and spontaneous language recovery. | Hope et al. [217] (2016), Yourganov et al. [117] (2016), Fridriksson et al. [203] (2018), Zavanone et al. [219] (2018), Forkel et al. [207] (2018), Pustina et al. [218] (2017), Del Gaizo et al. [214] (2017) | ||
| Pre-therapy global network integrity predicts positive therapy response. | Bonilha et al. [118] (2016) | |||
| RH AF | Therapy induces structural changes and normalization of structural connectivity. | Schlaug et al. [220] (2009), Wan et al. [221] (2014), van Hees et al. [177] (2014), McKinnon et al. [222] (2017) | ||
| LH temporal lobe | Local integration (preservation) predicts positive therapy response. | Bonilha et al. [118] (2016) | ||
Note that the table does not provide an exhaustive overview of the literature on predictors of aphasia recovery, but rather includes the most commonly studied biographical, neuropsychological, and neurobiological predictors of recovery, and empirical evidence for prediction of treated recovery is emphasized as relevant.
TPS, time post-stroke; pSTG, posterior superior temporal gyrus; SMG, supramarginal gyrus; AG, angular gyrus; STG, superior temporal gyrus; MTG, middle temporal gyrus; SLF, superior longitudinal fasciculus; AF, arcuate fasciculus; pMTG, posterior middle temporal gyrus; IFG, inferior frontal gyrus; SFA, semantic feature analysis; SE, speech entrainment; MFG, middle frontal gyrus; ROI, region-of-interest; DG, domain-general; RH, right hemisphere; LH, left hemisphere; PrCG, precentral gyrus.