Evoked related potentials (ERP) derived from continuous electroencephalography recording while subjects perform a cognitive task have a long tradition in cognitive neuroscience research. They are specifically well placed to answer questions on timing and momentary changes in cognitive strategies while they are also subjected to a lot of data preprocessing in order to improve signal to noise ratio, which can introduce artifactual patterns in results. AX-CPT is a complex version of a continuous performance task, which puts emphasis on maintenance of contextual cues and forces subjects to use proactive or reactive cognitive strategies to different degrees to successfully maintain their attention to stimuli. It is thought that proactive and reactive cognitive styles coexist in individuals and change according to current circumstances of cognitive processing, while their overall balance shifts due to different reasons, ageing being one of the most researched. In present study we sought to differentiate healthy young subject sample from healthy old subjects and patients with mild cognitive impairment, Parkinson’s disease and mild cognitive impairment related to Parkinson’s disease based on their responses to different parts of the AX-CPT trial: processing and maintaining the cue over short and long delay, inhibiting or activating response to target. Results will be presented and the possibility for the inclusion of this specific ERP in multimodal integrative markers of disease related cognitive decline will be discussed.