Ipsilateral hippocampal atrophy is associated with long‐term memory dysfunction after ischemic stroke in young adults

Abstract

Memory impairment after stroke in young adults is poorly understood. In elderly stroke survivors memory impairments and the concomitant loss of hippocampal volume are usually explained by coexisting neurodegenerative disease (e.g., amyloid pathology) in interaction with stroke. However, neurodegenerative disease, such as amyloid pathology, is generally absent at young age. Accumulating evidence suggests that infarction itself may cause secondary neurodegeneration in remote areas. Therefore, we investigated the relation between long-term memory performance and hippocampal volume in young patients with first-ever ischemic stroke. We studied all consecutive first-ever ischemic stroke patients, aged 18-50 years, admitted to our academic hospital center between 1980 and 2010. Episodic memory of 173 patients was assessed using the Rey Auditory Verbal Learning Test and the Rey Complex Figure and compared with 87 stroke-free controls. Hippocampal volume was determined using FSL-FIRST, with manual correction. On average 10 years after stroke, patients had smaller ipsilateral hippocampal volumes compared with controls after left-hemispheric stroke (5.4%) and right-hemispheric stroke (7.7%), with most apparent memory dysfunctioning after left-hemispheric stroke. A larger hemispheric stroke was associated with a smaller ipsilateral hippocampal volume (b=-0.003, P<0.0001). Longer follow-up duration was associated with smaller ipsilateral hippocampal volume after left-hemispheric stroke (b=-0.028 ml, P=0.002) and right-hemispheric stroke (b=-0.015 ml, P=0.03). Our results suggest that infarction is associated with remote injury to the hippocampus, which may lower or expedite the threshold for cognitive impairment or even dementia later in life.

Location, Infarct Load, and 3-Month Outcomes of Delayed Cerebral Infarction After Aneurysmal Subarachnoid Hemorrhage

“…We did not find difference in summative cognitive scores (MMSE and MoCA) between leftand right-sided DCI, in which different patterns of cognitive domain deficits were likely. 33 These different patterns of cognitive domain deficits might not be detected by summative cognitive scores. Hypodense lesions on CT at 4 to 6 weeks post treatment may not accurately detect all DCI.…”

Remote Lower White Matter Integrity Increases the Risk of Long-Term Cognitive Impairment After Ischemic Stroke in Young Adults

“…However, our previous work on longterm cognitive outcome in these young patients with ischemic stroke showed a low number of patients with aphasia. 12 Therefore, it seems unlikely that excluding these small number of patients largely influenced the generalizability of present results to young patients with ischemic stroke.…”

“…20 Intracranial volume was calculated as the sum of gray matter, white matter, and cerebrospinal fluid using VBM8. 12 Next, brain-extracted images 21 were registered, along with the lesion mask, to the Montreal Neurological Institute standard space by an affine transformation (12 degrees of freedom) using FSL-FLIRT (FMRIB Software Library -FMRIB's Linear Image Registration Tool), 21 followed by nonlinear registration using FNIRT (FMRIB's Nonlinear Image Registration Tool). 21 Next, all stroke masks were merged and averaged, which resulted in a lesion probability map.…”

“…6 Accumulating data suggest that, apart from temporary remote neurophysiological changes after stroke (ie, diaschisis), 7 a focal (ischemic) lesion could potentially affect longterm remote structural integrity (eg, of the hippocampus and thalamus) in the ipsilesional hemisphere after stroke, 3,[8][9][10][11] which has been associated with a worse poststroke memory performance. 11,12 Besides remote structural changes in the ipsilesional hemisphere, a few small neuroimaging studies (6-16 patients) in older patients with stroke (≥60 years) found loss of white matter integrity as remote as the contralesional hemisphere, 13 and this was associated with motor impairment ≤6 months after stroke 14,15 and poorer cognitive recovery 3 months after right middle cerebral artery stroke. 16 It is unknown whether lower microstructural integrity in areas remote from the initial stroke, including as remote as the contralesional hemisphere, is related to long-term (ie, years) cognitive dysfunction after stroke.…”

Asia Pacific Stroke Conference 2016. Abstracts of the Annual Conference of theAsia Pacific Stroke Organization (APSO) Combined with Stroke Society of Australasia, Brisbane, Qld., Australia, July 14-17, 2016: Abstracts

“…Background and Rationale: Smaller hippocampal volume in humans with cortical or subcortical lesions is associated with impaired cognition (Blum et al, 2012, Schaapsmeerders et al, 2015. Hippocampal neurogenesis continues throughout life.…”