Apathy, defined as a lack of motivation in behaviour, cognition and affect, is common in neurodegenerative diseases. Specific scales are available for the evaluation of apathy but it lacks objective evaluation methods.

The aim of this study is to evaluate the changes in reaction time task according to the presence or absence of reward stimulation and to assess the relation between these performances and apathy scales.

MATERIAL: 13 patients with Mild Cognitive Impairment (MCI), 15 patients with Alzheimer's disease (AD) and 91 elderly healthy subjects were enrolled. A computerized test using the experiment software E-prime® was designed to assess reaction times (in ms) in different experimental conditions after a training trial (neutral, stimulation, stress, stimulation after stress, extinction) and relation between the performances to the test and the Apathy Inventory (AI) scores (lack of initiative, lack of interest, emotional blunting) were observed.

METHOD: Using a computerized test, each patient is asked to press a button (mouse of the computer) each time the screen of the computer becomes completely white. After pressing the button, a randomized colorized geometric figure appears on the screen, and disappears automatically after a few seconds, replaced by a new white screen. Reaction time (in ms) between a white screen and a press of the button is analysed. After a training trial, reaction times are analysed in different experimental conditions: neutral - stimulation1 (patient gets points when pressing the button) - stress (alarm) - stimulation2 (patient gets points when pressing, after the stress trial) - extinction (similar to neutral condition).

Inclusion Criteria:

• Elderly patients with diagnosis of Alzheimer's Disease according to DSM-IV criteria
• MMSE >20

Exclusion Criteria:

• None
• Motor or psychiatric disorders