Definition of Global Hypoactivity and Apathy
Global hypoactivity consists of a severe and otherwise unexplained reduction in self-triggered activities (walking, communication, eating, self-care, etc.) and activities triggered by the environment (orienting reactions and difficulties in initiating and sustaining various activities—including tests). This overt behavioral change is usually associated with modifications in the cognitive and emotional domains. In the cognitive domain, several signs suggest impoverishment of the cognitive content; the patient frequently reports having an “empty mind” and does not actively gather new or relevant information. These aspects have been evidenced in everyday life by a lack of initiation, failure to enquire about and have consideration for events concerning close relatives, and reduced enthusiasm for previous sources of interest (leisure activities, occupations). In the emotional domain, patients and close relatives frequently report reduced motivation, flat emotion, blunted affect, disinterest, and indifference to their own concern and others. In problem-solving tasks, reduction in gathering relevant information has been evidenced by gaze analysis .
Many terms have been used to refer to this behavioral change: abulia, apathy, aspontaneity, pseudo-depressive state, lack of drive, poor motivation, inattention, indifference, anhedonia, and (in the extreme form of the disorder) akinetic mutism. Although all these terms refer to similar clinical conditions, their use differs according to the clinical context or the supposed mechanism of global hypoactivity. Abulia is defined as a reduction in movement and speech, slowed reactions, and difficulties sustaining activities [5 ] . Aspontaneity is defined as a severe reduction in self- triggered activities that is reversed by heteroactivation. Anhedonia refers to a reduction in the ability to experience pleasure and is more frequently used for patients with psychiatric conditions . Apathy derives from the Greek apathya (literally “lack of passion”), a word originally coined more than 2000 years ago by the Greek Stoic philosophers to refer to the condition of being free from emotions and passion . Apathy is defined by reduced motivation, loss of initiation, loss of interest, flat emotion, and blunted affect [8, 9]. Marin  has defined apathy as a syndrome of primary lack of motivation that is not attributable to emotional distress, intellectual impairment, or diminished consciousness.
Cummings et al.  emphasized on the loss of interest and motivation, including a lack of emotion, initiation, and/or enthusiasm. According to Sockeel et al. , apathy is a disorder of intellectual curiosity, action initiation, emotion, and self-awareness. Levy and Dubois  defined apathy as an observable behavioral syndrome consisting of a quantitative reduction in self-generated voluntary and purposeful behaviors. Robert et al.  have suggested that apathy is a motivation disorder that affects goal-directed behavior, cognitive activity, and emotions. A descriptive terminology (global hypoactivity associated with abulia, and/or apathy and/or aspontaneity) has been developed by the GREFEX study group .
Given that these terms all refer to the same clinical condition, the terms “global hypoactivity with apathy” and “apathy” will be used interchangeably in the present chapter.