Thinking may be distorted in such a way that ideas are not checked against reality. When a false belief is maintained in spite of convincing evidence to the contrary, the term delusion is used. This abnormality is common to bipolar, schizophrenic, and paranoid states, as well as the early stages of dementia. Often the story related by the patient has internal logic but is patently absurd. Psychotic patients may believe that ideas have been implanted in their minds by some outside agency, such as the internet, radio, television, or atomic energy; these thought control or “passivity feelings” are characteristic of schizophrenia, and sometimes of the psychosis of manic episodes. Also diagnostic of some forms of schizophrenia are distortions of logical thought, such as gaps in sequential thinking, intrusion of irrelevant ideas, and condensation of associations. Chapter 49 discusses these aspects of psychoses. Although mistaken notions along the lines of delusions do occur in the global confusional state, they change from moment to moment and are not firmly held, quite in contrast to the psychotic states.
Disturbances of Emotion, Mood, and Affect
The emotional life of an individual is expressed in a variety of ways. It is widely appreciated that there are marked individual differences in basic temperament. Throughout their lives some persons are cheerful, gregarious, optimistic, and free from worry, whereas others are just the opposite. The state of emotionality, and changes that are uncharacteristic to the individual lend themselves to observation and have clinical significance. Furthermore, some inherent personality traits may precede the development of overt mental disease. For example, the volatile, person is said to be liable to bipolar disease, and the suspicious, withdrawn, introverted person to schizophrenia and paranoia, but there are frequent exceptions to these statements.
Strong, persistent emotional states, such as fear and anxiety, may occur as reactions to life situations and are accompanied by numerous derangements of visceral function. If excessive, prolonged, and disproportionate to the stimulus, they are usually manifestations of an anxiety state or depression. In depression, almost all stimuli also tend to enhance the somber mood of unhappiness. Affective displays that are excessively labile and poorly controlled or uninhibited are a common manifestation of many cerebral diseases, particularly those involving the corticopontine and corticobulbar pathways. This disorder constitutes part of the syndrome of spastic bulbar (pseudobulbar) palsy, as discussed in Chaps. 22 and 24, but it may occur independently of any problem with brainstem function. Conversely, all emotional feeling and expression may be lacking, as in states of profound apathy or depression. Or excessive cheerfulness may be maintained in the face of serious, potentially fatal disease or other adversity—a pathologic euphoria. Finally, a patient’s emotional responses may be inappropriate to the stimulus, for example, a depressing or morbid thought may seem amusing and be attended by a smile, a bizarre affective state as in schizophrenia.
Temperament, mood, and other emotional experiences are evaluated by observing the patient’s behavior and appearance while questioning him about his feelings. For these purposes, it is convenient to divide emotionality into mood and affect. By mood is meant the prevailing internal emotional state of an individual. By contrast, affect (or feeling) refers to the outward emotional reactions evoked by a thought or an environmental stimulus. As such, it is the observable aspect of emotion. The patient’s language (e.g., the adjectives used), facial expression, attitude, posture, and speed of movement reflect prevailing mood. These distinctions are at times rather tenuous, but they are clinically valuable because pathologic processes may dissociate the two to an extreme degree.
Disturbances of Impulse (Conation) and Activity