Objective: To investigate alterations in the attention network in Parkinson’s disease patients with mild cognitive impairment (PD-MCI).

Background: MCI is a risk factor for dementia in PD.  Impairments in cognitive domains such as attention and executive processing are commonly observed in PD-MCI; however, neural mechanisms underpinning these deficits are poorly studied in PD. The present study aims to use task dependent fMRI to identify neural basis for deficits in attention and executive function in PD-MCI. This will assist with establishing neuroimaging markers for PD with dementia 

Methods: Seventeen PD patients and 7 age and gender-matched healthy controls participated. PD was further subdivided to the presence of MCI using a comprehensive cognitive battery according to the recommended diagnostic criteria (Litvan et al. 2012). Participants were scanned (3T Siemens PRISMA) using event-related fMRI to measure differences in attention network test between groups. Three different attention components of alerting, orienting, and executive control were calculated. (Fan et al. 2005). Behavioural reaction time and accuracy were analysed. fMRI data was analysed using SPM12 and whole brain analysis. Significance was determined as p<0.001 uncorrected, with cluster level FWE correction (p<0.05). 

Results: Ten PD patients were diagnosed with MCI with 1.5SD below norms. In alerting, PD-MCI showed increased activation in the medial cingulate cortex, inferior frontal gyrus and prefrontal and temporal thalamus compared to PD-nMCI. PD-nMCI showed increased activation in right occipital regions including calcarine gyrus and precuneus; bilateral hippocampus and cerebellar vermis. In executive control, PD-MCI also showed increased activation left posterior-medial prefrontal cortex, left insular, bilateral inferior frontal gyrus and right prefrontal thalamus.

Conclusions: Increased activation posterior and frontal regions found in the PD group may indicate impaired deactivation of default mode network in PD particularly in PD-MCI compared to controls.  Whilst, thalamus plays a major role in alerting and executive function, excessive activation observed particularly in PD-MCI may relate to compensatory activation in order to complete the task. This abstract is also submitted to OHBM 2017 Conference. 

References: Litvan, I., J. G. Goldman, A. I. Tröster, B. A. Schmand, D. Weintraub, R. C. Petersen, B. Mollenhauer, C. H. Adler, K. Marder, C. H. Williams‐Gray, D. Aarsland, J. Kulisevsky, M. C. Rodriguez‐Oroz, D. J. Burn, R. A. Barker and M. Emre (2012). ‘Diagnostic criteria for mild cognitive impairment in Parkinson’s disease: Movement Disorder Society Task Force guidelines.’ Movement Disorders, vol. 27, no. 3, pp. 349-356.

Fan, J., B. D. McCandliss, J. Fossella, J. I. Flombaum and M. I. Posner (2005). ‘The activation of attentional networks.’ Neuroimage, vol. 26, no. 2, pp. 471-479. Litvan, I., J. G. Goldman, A. I. Tröster, B. A. Schmand, D. Weintraub, R. C. Petersen, B. Mollenhauer, C. H. Adler, K. Marder, C. H. Williams‐Gray, D. Aarsland, J. Kulisevsky, M. C.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/altered-attentional-brain-network-in-parkinsons-disease-with-mild-cognitive-impairment/