The Tree Drawing Test in Evolution: An Explorative Longitudinal Study in Alzheimer's Disease

Objective To study the evolution of the Tree Drawing Test (TDT) in a group of Alzheimer's disease (AD) patients. Methods A total of 33 AD patients were consecutively evaluated by Mini Mental State Evaluation (MMSE) and TDT. The evolution of the TDT parameters, trunk-to-crown (TC) and space occupation (SO) index, were analyzed. Results The median age at first visit was 79 years. Globally, trees drawn by patients showed an evolution characterized by a progressive reduction of the crown compared to the trunk. TC index showed a significant linear growth change (2.52 points per year) while SO index did not significantly increase. No significant associations were found examining the relations between MMSE and TC and SO index. Conclusions TDT could represent a complementary technique to the main neuropsychological screening tests for orienting cognitive impairment diagnosis and an aid in following the evolution of cognitive impairment over time in AD patients.