Memory impairment is common and an area of unmet need after stroke. The mechanisms of impairment, and subsequent improvement or decline, are not well understood. Lesion location predicts verbal memory early after stroke, with lesions in the left posterior cerebral artery territory (PCA) or left thalamus predicting impaired verbal recall. Memory recovery by recruitment of intact medial temporal white matter pathways should depend on both lesion location and pre-existing status of white matter tracts. From a cohort of 187 patients with recent, ischaemic stroke, 85 underwent 1-year follow-up evaluation of memory. A subgroup (n=30) also underwent high angular resolution diffusion MRI with tractography-based reconstruction of temporal association tracts. Lesion location remained important at 1 year: verbal memory remained poor in patients with left PCA territory lesions but improved in those with lesions in other locations (F(8,29) = 2.49, p < .05). Baseline severity of impairment was also a predictor of performance at 1 year. In the imaging subgroup, there was a significant interaction between lesion location, baseline severity and microstructure of the fornix – a key tract for memory in the healthy brain – on recovery of verbal recall performance over one year (F(3,19) = 6.38, p < .01). These results suggest that recovery of memory after stroke depends on both the pattern of initial injury and the status of undamaged tracts, which can be recruited to support residual memory performance. Long-term recovery of post-stroke cognitive impairment relies on the status of intact medial temporal white matter pathways.

PREDICTORS OF EPISODIC MEMORY RECOVERY ONE YEAR AFTER STROKE