Klinische Neurophysiologie 2014; 45 - P2
DOI: 10.1055/s-0034-1371215

Localisation of attentional function in Lewy body dementia and Alzheimer's disease

X Kobeleva 1, M Firbank 2, JP Taylor 2
  • 1Medizinische Hochschule Hannover, Neurologie, Hannover, Deutschland
  • 2Newcastle General Hospital, Institute for Ageing and Health, Newcastle Upon Tyne, Großbritannien

Question: Fluctuations in cognition and attention is a core symptom of Lewy Body Dementia (LBD). Yet the aetiology of this symptom is incompletely understood but may relate to fronto-parietal network dysfunction. Therefore we examined the performance and brain activation in LBD patients applying a modified ANT (attention network task) using an event-related functional magnetic resonance (fMRI) paradigm and compared those activations with healthy controls and patients with Alzheimer's disease (AD).

Methods: 19 LBD patients, 25 AD patients and 23 age-matched healthy controls (HC) underwent an assessment of global cognitive function before performing the ANT in the scanner. Reaction times (RT) were compared between groups. Imaging data were then submitted to a GLM analysis using SPM 8 (Statistical Parametric Mapping).

Results: The LBD group was significantly slower in RT performance than the other groups. However, SPM(t) analysis revealed comparable frontoparietal network activations to the executive component of the ANT in all three groups. Comparingthe easy versus hard incongruent tasks we did not find any activation in the control group, whereas the AD, and also to a lesser extent the DLB group exhibited increased occipito-parietal activity. When we contrastedAD to DLB, significantly increased activity in the inferior parietal region could be seen in the AD group. As the reaction times were longer in the DLB group, we investigated the effect on the haemodynamic response function. DLB had broader and/or delayed responses in the occipital, parietal and precentral regions.

Conclusions: These findings suggest a spatially intact network with no evidence of topologically specific deficits in LBD. However, patients with DLB have slow responses, which are not only due to motor impairment, but are also displayed on a cognitive level. On the contrary the AD have greater activity in the parietal lobe, which might be interpreted as an compensation mechanism.