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Research paper
The neural correlates of road sign knowledge and route learning in semantic dementia and Alzheimer's disease
  1. S Luzzi1,
  2. V Cafazzo1,
  3. A Damora1,
  4. K Fabi1,
  5. F M Fringuelli2,
  6. G Ascoli2,
  7. M Silvestrini1,
  8. L Provinciali1,
  9. C Reverberi3,4
  1. 1Department of Experimental and Clinical Medicine, Marche Polytechnic University, Ancona, Italy
  2. 2Nuclear Medicine Department, Ospedali Riuniti di Ancona, Ancona, Italy
  3. 3Department of Psychology, Università Milano, Bicocca, Milano, Italy
  4. 4NeuroMi, Milan Center for Neuroscience, Milano, Italy
  1. Correspondence to Dr Simona Luzzi, Department of Experimental and Clinical Medicine, Neurologic Clinic, Marche Polytechnic University, Via Conca, 1, Torrette di Ancona, Ancona, 60126 Italy; s.luzzi{at}


Background Although there is a growing body of research on driving and Alzheimer's disease (AD), focal dementias have been understudied. Moreover, driving has never been explored in semantic dementia (SD).

Methods An experimental battery exploring road sign knowledge and route learning was applied to patients with SD and AD selected in the early-moderate stage of disease and to a group of healthy participants. Neuropsychological data were correlated to cerebral hypometabolism distribution, investigated by means of positron emission tomography.

Results The two dementias showed opposite profiles. Patients with SD showed poor road sign knowledge and normal performance in route learning. By contrast, patients with AD showed low performance in route learning test with preservation of semantic knowledge of road signs. In SD, there was a correlation of semantic knowledge impairment with hypometabolism in the left temporolateral cortex. No correlation between the AD region of interests (ROIs) and the relevant behavioural indices was found, while in the whole-brain analysis there was a significant correlation between route learning and the superior frontal gyrus.

Discussion and conclusions For the first time, driving skills were explored in SD, and it is showed a differential profile from the one detected in AD. We demonstrate that the left anterior temporal cortex is implicated in road sign knowledge, while a distributed cortical network, including the frontal cortex, is likely to process route learning.


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