The phenomenon of irritability, or an irritable mood, must be familiar to almost everyone, exposed as we are to all of the noise, niggling inconveniences, and annoyances of daily life. It is, nevertheless, a difficult symptom to interpret in the context of psychopathology. Freud used the term Reisbarkeit in a restricted sense to denote an undue sensitivity to noise—and considered it a manifestation of anxiety, but obviously, this symptom has a much broader connotation and significance. For one thing, some people are by nature irritable throughout life. Also, irritability is an almost expected reaction in overworked, overwrought individuals, who become irritable by force of circumstances. An irritable mood or feeling may be present without observed manifestations (inward irritability), or there may be an overt loss of control of temper, with irascible verbal and behavioral outbursts, provoked by trivial but frustrating events.
Irritability in the foregoing circumstances can hardly be considered a departure from normal. However, when it becomes a recurrent event in a person of normally placid temperament, it assumes greater significance, for it may then signify the onset of a frontal lobe disorder including a variety of dementias, or of an ongoing anxiety state or depression. Irritability is also a common symptom of obsessive–compulsive disorders. Here the irritability tends to be directed inward, indicating perhaps a sense of frustration with personal disability (Snaith and Taylor). Depressed patients are frequently irritable; as a corollary, this symptom should always be sought in patients suspected of being depressed. The days preceding menses and the mother’s common postnatal mood disorder are characterized by high levels of outwardly directed irritability. Short-temperedness and irritability are also common features of the manic state. The most extreme degrees of irritability, exemplified by repeated quarrelsome and assaultive behavior (irritable aggression), are rarely observed in anxiety disorders and endogenous depression but are usually the mark of sociopathy and conventional brain disease (in the past, general paresis). Such irritable aggression is also observed in some patients with Alzheimer disease and other types of dementia, particularly of the frontotemporal type, and following traumatic contusions or encephalitis of the temporal and frontal lobes.
Cause, Mechanism, and Biologic Significance of Nervousness and Anxiety
These have been the subjects of much biologic and psychologic speculation, and completely satisfactory explanations are not available. As noted above, some individuals go through life in a chronic state of low-grade anxiety, the impetus for which may or may not be apparent. Spontaneous episodes of anxiety demand another explanation. Some psychologists regard anxiety as anticipatory behavior, that is, a state of uneasiness about something that may happen in the future. William McDougall spoke of it as “an emotional state arising when a continuing strong desire seems likely to miss its goal.” The primary emotion, somewhat muted perhaps, may be one of fear, and its arousal under conditions that are not overtly threatening may be explained as a conditioned response to some recondite component of a formerly threatening stimulus. The James-Lange theory of emotion, which is dated but should not be dismissed, suggests that the dominant feature of the experience of anxiety is simply the physical experience of the associated autonomic discharge.
Infusions of lactic acid can make the symptoms of anxiety worse and, in susceptible individuals, may elicit a panic attack. The patient seems not to tolerate the work or exercise needed to build up stamina. The urinary excretion of epinephrine was found to be elevated in some patients with panic disorder; in others, there is an increased urinary excretion of norepinephrine and its metabolites. During periods of intense anxiety, aldosterone excretion is increased to 2 or 3 times normal.