White matter hyperintensities as a predictor of aphasia recovery

OBJECTIVE:To examine the relationship between baseline white matter hyperintensities (WMH) and change in naming, content production, and efficiency following treatment in subacute aphasia. We hypothesized that more severe baseline WMH would result in less improvement with treatment. DESIGN:Retrospective analysis of a cohort from a double-blind randomized controlled trial (RCT). SETTING:Outpatient clinical setting or participant home. PARTICIPANTS:We retrospectively reviewed imaging and behavioral data for 52 participants with subacute aphasia due to left-hemisphere ischemic stroke enrolled in the RCT. RCT inclusion criteria: English proficiency, normal/corrected-to-normal hearing/vision, and no history of neurological conditions other than the stroke resulting aphasia. One participant with a chronic right-hemisphere lesion was retained as she presented with no residual deficits on neurological examination. Individuals with scalp sensitivities or on medications that lower seizure threshold or any N-methyl-D-aspartate (NMDA) antagonists were excluded. Of the 52 participants, for this analysis, two were excluded for not having an MRI, and seven were excluded for not participating in treatment or pre/post assessment for at least one outcome, resulting in final sample of 43 participants (20 female sex, M[SD] age=64.4[11.9] and M[SD] education=14.9[3.1] years). INTERVENTIONS:Participants received 15 sessions (2-3 times/week) of computerized lexical-semantic (i.e., verification) treatment with [sham/active] transcranial direct current stimulation (tDCS). Sessions were approximately 45 minutes each (tDCS for first 20 minutes). MAIN OUTCOME MEASURES:Naming accuracy, content units (CUs, a measure of semantically accurate production), and efficiency (i.e., syllables/CU) on a picture description task. RESULTS:Periventricular WMH severity was independently associated with recovery in picture naming for the active tDCS group. Deep WMH severity was associated with recovery for content unit production for the sham tDCS group. CONCLUSION:Baseline periventricular and deep WMH, among other factors, may be an important consideration for prognosis and treatment planning, especially when considered in conjunction with tDCS treatment.