The device (10) disclosed herein assists in the diagnosis and classification of neurodegenerative diseases through the assessment of a subject's visuo-spatial ability. The device (10) has a touch-screen display (11) into which a user can input data utilizing a stylus (13) or the like. A position reader is provided, linked to a position data storage means and also a timer to link a time value to said position data, the time value being stored in a time data storage means. Storage means is also provided for preset-value data relating to known data on medical conditions, with the preset-value data having been produced in accordance with an evolutionary algorithm. A comparator compares the user input data with the preset-value data, and the result is output.