Impulsive Behaviour
Impulsive behaviour is a sudden action, usually aggressive in quality, carried out without any apparent forethought, planning, or discernible rational motive. It is common enough in catatonia, where a patient may suddenly strike another person, throw an object, or smash something, with no identifiable reason once the act has occurred, and no build-up that would have allowed it to be anticipated.
This has traditionally been considered difficult to classify precisely, since impulsive actions do not fit neatly into either purely goal-directed or purely non-goal-directed categories; they are best understood as sudden, unplanned actions that occur on the spur of the moment, a pattern that can occur in people without mental illness as well as being common in catatonia.
Recognition features
- A sudden action, typically aggressive, carried out without warning, planning, or forethought
- No rational or discernible motive can usually be identified after the fact
- Common in catatonia, though a tendency toward impulsive action on the spur of the moment also occurs in people without mental illness
- May include sudden wandering away from home or work, or actions carried out despite the near-certainty of being caught
Eliciting it at interview
- Ask about any history of sudden, unplanned actions, particularly aggressive ones, and explore whether the person can identify any reason or trigger after the fact
- Consider the safety implications carefully in an environment where a patient has shown impulsive aggressive behaviour, given its sudden and unpredictable nature
- Distinguish from goal-directed aggression, such as violence arising from a specific delusional belief or in response to hallucinatory command, by the absence of any identifiable underlying motive
Distinguishing features
- Differs from goal-directed aggressive behaviour, such as violence driven by a specific delusion or command hallucination, in lacking any identifiable underlying motive or rational explanation
- Differs from negativism and ambitendency, which concern resistance to or conflict about a requested action, whereas impulsive behaviour is a spontaneous, unprompted action of the patient's own
- Differs from extended suicide, which, despite superficially appearing sudden, is typically driven by a specific, sustained delusional belief system rather than arising without any identifiable motive
Common misconceptions
- That impulsive behaviour in catatonia reflects calculated or purposeful aggression; the defining feature is the absence of any rational motive that can be identified even after careful assessment
- That impulsivity is unique to psychiatric illness; occasional impulsive action on the spur of the moment occurs in people without mental illness too, though it may be more frequent or severe in catatonia
Related phenomena
Negativism · Pathological Drunkenness
Practice this
Without any warning or apparent reason, a catatonic patient suddenly strikes a fellow patient, and afterward is unable to give any explanation for why he did it. What is this? · A mother with severe, delusional depressive illness, convinced she has passed an incurable genetic curse to her children, kills her two children before attempting to take her own life, later explaining she believed she was sparing them from a lifetime of suffering. Before revealing the answer: is this impulsive behaviour? · A patient suddenly carries out a violent act. Before revealing the answer, decide what distinguishes impulsive behaviour from extended suicide. · You suspect impulsive behaviour in a patient. Before revealing the answer, decide how you would assess for this. · Explain why impulsive behaviour is described as common enough in catatonia specifically, despite also occurring in people without mental illness.
Illustration
Without any warning or apparent provocation, a patient with catatonia suddenly sweeps a stack of plates off a dining table during a quiet mealtime, and when asked afterward why he did it, he appears genuinely unable to offer any explanation, seeming almost as puzzled by the act as those who witnessed it.
References
- Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 8, 'Motor Disorders'.