Abstract T P364: Longitudinal Evaluation of Functional Magnetic Resonance Imaging on Working Memory in Patients after Transient Ischemic Attack

Abstract

OBJECTIVE: Transient ischemic attack (TIA) can increase the risk of cognitive decline, especially in attention-executive-psychomotor functioning. However, whether TIA patients have altered patterns of brain activation during this function, and whether there is a dynamic change on cerebral activity patterns, have not been examined to date. This study is designed to using functional magnetic resonance imaging (fMRI) to investigate longitudinal changes in brain activation during a verbal working memory (VWM) task in patients with TIA. METHODS: The current study included 25 patients with first-ever TIA in right hemisphere and 25 healthy volunteers. N-Back VWM task-related fMRI were conducted one week and three months after TIA onset. The brain activity evoked by n-back task in the patients was assessed and compared with that of the controls. Significant changes in cerebral activation over time were also observed in TIA patients. RESULTS: The groups did not differ on any demographic, cognitive and task performance variables. Compared with healthy subjects, patients at one week after TIA demonstrated increased activity in bilateral inferior frontal gyrus (IFG), right dorsolateral prefrontal cortex (DLPFC), insula, inferior parietal lobe (IPL) and cerebellum during the task. However, at 3-month follow-up, the task-related brain activity in patients was clearly less recruited, and only right IFG still exhibited increased activity. Moreover, a direct comparison of fMRI data between one week and three months after TIA showed that there was increased activation in bilateral middle temporal gyrus (MTG), right DLPFC, IPL, cerebellum and left IFG in patients at one week after TIA. CONCLUSIONS: These findings support the hypotheses that the patterns of brain activity during VWM performance may change for a period of time post-TIA despite the cessation of clinical symptoms. They also provide evidence of a progressive normalization of the VWM activation pattern after transient episodes of ischemia in patients with first-ever TIA.