Neural correlates of performance on the different scoring systems of the clock drawing test.

The aim of this study was to identify brain regions associated with performance on various measures of the clock drawing test (CDT) using magnetic resonance imaging (MRI).We recruited 48 participants (four healthy, eight with mild cognitive impairment and 36 with Alzheimer's disease). Multiple regression analyses identified relationships between each CDT scoring system (Shulman CDT, Rouleau CDT and CLOX1) and regional gray matter (GM) volume.CDT scores were positively correlated with regional GM volume in the right parietal lobe for all three CDT scoring systems. In addition, CDT scores were positively correlated with regional GM volume in the bilateral posterior temporal lobes for the Shulman CDT, in the right posterior inferior temporal lobe for the Rouleau CDT and in the right posterior superior temporal lobe for the CLOX1.Although the scoring systems share commonalities, each CDT scoring system may reflect different areas of brain damage.