Adaptation of neurostimulation therapy to age-related physiological changes

An implantable device for delivering neurostimulation therapy to a patient, the implantable device comprising:

• an electrode array comprising a plurality of electrodes;
• a pulse generator connectable to the electrode array, the pulse generator configured to generate a stimulus pulse via the electrodes to electrically excitable tissue of the patient;
• and
• a controller configured to measure a sensitivity of the patient by:
• measuring a noise level at an output of an ECAP detector of the implantable device in open-loop mode;
• measuring a noise level at the output of the ECAP detector of the implantable device in closed-loop mode;
• determining a ratio of the noise level in closed-loop mode to the noise level in open-loop mode;
• and
• determining the sensitivity from the ratio and a controller gain of the implantable device in closed-loop mode.