Figure 1.

Factors regulating mitohormesis and mitophagy. Adenosine monophosphate (AMP)-dependent kinase (AMPK) signalling, mitochondrial unfolded protein response (UPRmit), Silent information regulator of transcription (Sirtuin) signalling, inhibition of mammalian target of rapamycin (mTOR), caloric restriction and physical exercise induce low levels of ROS in mitochondria. ROS, at low levels, activate stress resistance mechanisms (mitohormesis), resulting in longevity. However, increased amounts of ROS in mitochondria are responsible for ageing, which is a major risk factor for AD and is influenced by APOE status and a variety of lifestyle factors. AMPK signalling, UPRmit, Sirtuin signalling, mTOR inhibition, caloric restriction and physical exercise also induce the mitophagy process, which is defective in AD.