Keep calm and manage impulsivity: Mood as a modulator of impulsive behaviour

This study investigated how different mood states affect distinct subtypes of impulsivity: motor impulsivity [measured with the Stop Signal (SST) and the 5-Choice Serial Reaction Time Task (5-CSRTT)], reflection impulsivity [assessed with the Information Sampling Task (IST)], and temporal impulsivity (the Delay Discounting Questionnaire). Eighty healthy volunteers completed two experimental sessions. During session 1, which served as a baseline measure, participants underwent a neutral mood induction procedure. In Session 2, they were randomly allocated to one of the mood-induction groups (Neutral, Positive, Sad, and Anxiety). Mood state ratings included bipolar visual analogue scales on mood (positive/negative), tension/relaxation and arousal (tired/active). No group effect was found on any of the impulsivity measures.24 Correlational analyses between mood changes (following the mood manipulation procedures) and behaviour in the tasks revealed that increased relaxation was related to increased information sampling in the IST (decreased reflection impulsivity). In addition, the more active subjects reported to be, the more likely they were to choose a delayed reward over the immediate one (decreased temporal impulsivity). These results indicate that subjective changes in mood state are associated with behavioural impulsivity levels. Importantly, distinct facets of impulsivity (reflection, motor and temporal) are differently affected by changes in mood state.

Impulsivity in humans: neurobiology and pathology

Impulsivity refers to premature behaviours and rash, poorly considered decisions which are made in spite of negative consequences. It is not a singular entity, consisting of a number of sub-categories under the two broad headings of motor and decisional impulsivity. The subtypes of motor impulsivity are laid out first, discussing waiting impulsivity, also known as premature responding, which can be a predictor of addiction, and response inhibition impulsivity, which is the capacity to inhibit pre-potent response. The chapter then explores the forms of decisional impulsivity, such as delay discounting and reflection impulsivity, along with their relation to attention-deficit/hyperactivity disorder. Finally, the prevalence of impulsivity across disorders as wide-ranging as obsessive–compulsive disorder and Huntington’s disease is discussed, and a case study of Parkinson’s-related impulsivity is presented.

Disentangling the effects of cannabis and cigarette smoking on impulsivity

Background: Cannabis smoking and cigarette smoking often co-occur, yet limited research has investigated the potentially different role impulsivity may play when these behaviours occur in isolation, compared with in combination. Aims: This study examined trait and behavioural impulsivity as a function of both cigarette and cannabis smoking. Methods: Trait impulsivity (BIS-11) was compared between 44 non-smokers, 76 cigarette only, 47 cannabis only and 58 cannabis plus cigarette smokers. The effects of cigarette and cannabis smoking on behavioural impulsivity (stop-signal and information sampling tasks) were then assessed in 87 of these participants during a laboratory session. Results: Trait impulsivity was significantly higher in cigarette smokers than non-smokers, irrespective of cannabis use, except for motor impulsivity, where cigarette smoking was only associated with elevated trait impulsivity in non-smokers of cannabis. Dimensions of trait impulsivity were significantly positively related to cigarette smoking frequency and nicotine dependence, but not to cannabis smoking frequency or dependence. Smoking cigarettes or cannabis was associated with significantly impaired reflection impulsivity relative to not smoking either substance. However, no additional increases in reflection impulsivity were observed in those who smoked both cigarettes and cannabis. No group differences in response inhibition were detected. Conclusions: Heightened trait impulsivity appears to be uniquely related to cigarette smoking, whilst the smoking of cigarettes or cannabis is associated with impairments in reflection impulsivity. Improved outcomes for treating cannabis dependence may result from encouraging concomitant cigarette smokers to cease using both drugs simultaneously in order to reduce heightened impulsivity and risk of relapse.

Short-term fasting selectively influences impulsivity in healthy individuals

Previous research has shown that short-term fasting in healthy individuals (HIs) is associated with changes in risky decision-making. The current experiment was designed to examine the influence of short-term fasting in HIs on four types of impulsivity: reflection impulsivity, risky decision-making, delay aversion, and action inhibition. HIs were tested twice, once when fasted for 20 hours, and once when satiated. Participants demonstrated impaired action inhibition when fasted; committing significantly more errors of commission during a food-related Affective Shifting Task. Participants also displayed decreased reflection impulsivity when fasted, opening significantly more boxes during the Information Sampling Task (IST). There were no significant differences in performance between fasted and satiated sessions for risky decision-making or delay aversion. These findings may have implications for understanding eating disorders such as Bulimia Nervosa (BN). Although BN has been characterised as a disorder of poor impulse control, inconsistent findings when comparing individuals with BN and HIs on behavioural measures of impulsivity question this characterisation. Since individuals with BN undergo periods of short-term fasting, the inconsistent findings could be due to differences in the levels of satiation of participants. The current results indicate that fasting can selectively influence performance on the IST, a measure of impulsivity previously studied in BN. However, the results from the IST were contrary to the original hypothesis and should be replicated before specific conclusions can be made.

Impulsivity and decision-making in obsessive-compulsive disorder after effective deep brain stimulation or treatment as usual

ObjectiveImpulsivity and impaired decision-making have been proposed as obsessive-compulsive disorder (OCD) endophenotypes, running in OCD and their healthy relatives independently of symptom severity and medication status. Deep brain stimulation (DBS) targeting the ventral limb of the internal capsule (vALIC) and the nucleus accumbens (Nacc) is an effective treatment strategy for treatment-refractory OCD. The effectiveness of vALIC-DBS for OCD has been linked to its effects on a frontostriatal network that is also implicated in reward, impulse control, and decision-making. While vALIC-DBS has been shown to restore reward dysfunction in OCD patients, little is known about the effects of vALIC-DBS on impulsivity and decision-making. The aim of the study was to compare cognitive impulsivity and decision-making between OCD patients undergoing effective vALIC-DBS or treatment as usual (TAU), and healthy controls.MethodsWe used decision-making performances under ambiguity on the Iowa Gambling Task and reflection impulsivity on the Beads Task to compare 20 OCD patients effectively treated with vALIC-DBS, 40 matched OCD patients undergoing effective TAU (medication and/or cognitive behavioural therapy), and 40 healthy subjects. Effective treatment was defined as at least 35% improvement of OCD symptoms.ResultsOCD patients, irrespective of treatment modality (DBS or TAU), showed increased reflection impulsivity and impaired decision-making compared to healthy controls. No differences were observed between OCD patients treated with DBS or TAU.ConclusionOCD patients effectively treated with vALIC-DBS or TAU display increased reflection impulsivity and impaired decision-making independent of the type of treatment.