The neural correlates of road sign knowledge and route learning in semantic dementia and Alzheimer's disease.

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.

Complementary role of whole body scan and serum thyroglobulin determination in the follow-up of differentiated thyroid carcinoma.

In 233 patients with differentiated thyroid carcinoma previously treated by total thyroidectomy supplemented, when necessary, with a therapeutic dose of 131I, serum thyroglobulin determinations and whole body scans were simultaneously performed. 82 of the 233 showed local or distant metastases: they were detected by both tests only in 36 cases. In 43 patients thyroglobulin was positive but without pathological concentrations of 131I at whole body scan were observed. The remaining 3 cases were detected on the basis of the positive whole body scan only, without increase in the circulating thyroglobulin. These results suggest that caution should be taken when considering thyroglobulin determination as possible substitutive test of whole body scan in the follow-up of differentiated thyroid carcinoma. However, for optimal sensitivity and reliability the complementary role of the two tests is stressed.