Correlation Between Cognition and Neuroimaging in TIA Patients

Context:

Cognitive impairment is common after a stroke. Out of 100 patients who have suffered a stroke, 50 will develop cognitive impairment. For 16 of them, they will be responsible for an impact on autonomy (major cognitive disorder). They are conventionally attributed either to the location of the lesions or to their general volume. However, recent literature emphasizes the presence of cognitive impairment after a transient ischemic attack (TIA), when by definition the symptoms are transient and imaging without recent ischemic injury. The mechanisms of cognitive impairment in TIA are therefore poorly understood at present. There is evidence in animal models and humans for persistent brain toxicity from ischemia even in the absence of established necrosis. However, to what extent this toxicity may explain the cognitive impairment seen in TIA is not known. Indeed, the latter could just as much have the effect of vascular risk factors which significantly increase cognitive risk even in the absence of an acute event.

Objective:

The objective of the Cog-TIA program is therefore to identify whether the transient ischemic attack may be responsible for long-term structural changes in neuroimaging in the ischemic territory and whether these changes are correlated with changes in cognitive efficiency.

Material and methods:

The project is based on the Normandy-Stroke population cohort which includes patients from Caen and the surrounding area who have had a stroke or TIA. The protocol provides for neuropsychological tests evaluating the main cognitive domains at 1 year and 3 years after the initial event. The Cog-TIA project is designed as an ancillary study to the Normandy-Stroke project with the objective of including 50 patients from this cohort who presented with a transient ischemic attack. Each patient will receive a structural MRI at the same time as the neuropsychological assessments scheduled for the Normandy-Stroke study. Analyzes will be performed from T1 sequences, Proton density with centered on the hippocampus and diffusion tensors. For the T1 and proton density sequences, the analyzes will compare the volumes of the different structures longitudinally (in particular: the total hippocampal volume and of the subfields, lobar, thalamic and pallidal volumes). For the diffusion tensor analyzes, the anisotropy maps will be compared longitudinally. For each structure showing significant variation during follow-up, correlations will be made with the decline in performance on neuropsychological tests calculated using composite scores. Cognitive decline may be partly attributed to TIA if it is correlated with abnormalities in the affected hemisphere.