3. Impulsivity / inhibition problems with ADHD

Author: Ulrich Brennecke
Review: Dipl.-Psych. Waldemar Zdero

Impulsivity is a complex construct and includes risky behavior in relation to rewards, inappropriate and premature reactions and an impairment of response inhibition.¹ Excessive impulsivity is also referred to as a disorder of impulse control (inhibition). Impulsivity has advantages in certain life situations where quick focus and quick decisions are required² or when gathering resources³ and appears to be primarily dopaminergic⁴, but also noradrenergic¹ controlled.

Impulsivity problems in ADHD affect ADHD-HI and ADHD-C in particular, and ADHD-I to a lesser extent.
Impulsivity is divided into action impulsivity and decision impulsivity (choice impulsivity).⁵
Action impulsivity is characterized by spontaneous, immediate action without forethought and a lack of inhibition of reactions. Symptoms include excessive talking, blurting out, not being able to wait and interrupting.
Choice impulsivity (Temporal Reward Discounting) involves the devaluation of distant rewards and the preference for small, immediate rewards as well as the inability to postpone reinforcement and reward. This form of impulsivity occurs not only in ADHD but also in other disorders and correlates with problems in decision making and delay aversion.

In children, impulse control problems or inhibition problems are manifested by interrupting, bursting out and difficulties waiting. In adults, they manifest themselves through spontaneous decisions, recklessness in dangerous situations or excessive cell phone use. Impulsivity is one of the main symptoms of ADHD, but is not conclusive evidence of ADHD and can also occur in other disorders. The symptoms are not culturally dependent. Even if children were culturally expected to be more subordinate and subordinate, the same problems were seen in action impulsivity and choice impulsivity when waiting⁶

Impulsivity is a symptom that also occurs with other mental health problems⁷
Impulse control problems are also symptoms of stress and manifest themselves in impulsivity, riskier decisions and problems with decision making. People with ADHD often exhibit increased risk-taking behaviors, especially those with externalizing symptoms. This can be seen in a preference for risky sports.
Increased risk-taking is both an ADHD symptom and a stress symptom. It correlates with impulsivity and hyperactivity, but not with anxiety. The increased willingness to take risks usually ends again after a stressful situation.

Novelty seeking and sensation seeking are similar psychological constructs that describe the search for new and exciting experiences.
Novelty Seeking is associated with Harm Avoidance and Reward Dependence, Sensation Seeking consists of the sub-constructs Thrill and adventure seeking, Experience seeking, Disinhibition seeking and Boredom susceptibility.
Both correlate with ADHD-HI and ADHD-C and are associated with stress, depression and other mental disorders.
Novelty seeking may be associated with low arousal and the DRD4-7R gene variant. People with Novelty Seeking may need more intense stimuli to feel interest and motivation. Risky behavior, such as drug use or promiscuous behavior, may be an expression of sensation seeking. The response to reward delays may be impaired in people with Novelty Seeking.

• 3.1. Types of impulsivity / inhibition problems
  • 3.1.1. Action impulsivity (AI)
  • 3.1.2. Choice impulsivity: devaluation of distant rewards (delay aversion, reward discounting, choice impulsivity, CI)
• 3.2. Impulse control problems / inhibition problems as ADHD symptoms
  • 3.2.1. Manifestations of inhibition problems in children
  • 3.2.2. Manifestations of inhibition problems in adults
  • 3.2.3. Impulse control disorder as an extreme form
• 3.3. Impulse control problems as symptoms of stress
• 3.4. Increased willingness to take risks
  • 3.4.1. Riskier decisions as an ADHD symptom
  • 3.4.2. Increased risk behavior as an ADHD symptom
  • 3.4.3. Increased willingness to take risks as a symptom of stress
• 3.5. Novelty Seeking / Sensation Seeking
• 3.6. Devaluation of later rewards (delay discounting / reward discounting)
  • 3.6.1. Devaluation of later rewards as an ADHD symptom
  • 3.6.2. Devaluation of later rewards as a stress symptom
• 3.7. Delay aversion
  • 3.7.1. Delay aversion in ADHD
    • 3.7.1.1. Impatience; waiting is perceived as unpleasant
    • 3.7.1.2. Correlation of delay aversion with other symptoms
  • 3.7.2. Delay aversion as a stress symptom

3.1. Types of impulsivity / inhibition problems¶

Impulsivity is divided into:⁸

• Action impulsivity: rapid reaction impulsivity of action (AI)⁹
• Choice impulsivity: cognitive / decision impulsivity (CI)¹⁰

Inhibition problems are primarily attributed to ADHD-HI and ADHD-C.¹¹ This also applies to elective impulsivity.¹²
Impulsivity usually results from inhibition problems. Inhibition problems often manifest themselves, but not only through impulsivity problems.

3.1.1. Action impulsivity (AI)¶

Action impulsivity manifests itself as:

• Tendency to act immediately, with diminished foresight and no connection to the current demands of the environment
  • a reduced ability to inhibit prepotent reactions
  • a failure of voluntary motor inhibition or disinhibition (inhibition)
• Consequences of a problem with self-regulation and thus inhibition.¹³¹⁴ Inhibition is the ability to inhibit (suppress) or control an impulsive (automatic) reaction and instead act in a way that is adapted to the situation.

Symptoms of action impulsivity in ADHD are:¹⁵

• Excessive speaking
• Bursting out
• Can’t wait until it’s your turn
• Interrupt
• Impulse purchases¹⁶

Impulsivity is something different from an emotional outburst.
Affective outbursts are (brief) emotional outbursts, i.e. intense, uncontrolled reactions, e.g. brief outbursts of anger.

As is known from decision research, the signal to perform an action can be measured up to 10 seconds earlier than the person with ADHD is aware that they have made a decision.¹⁷ Even 200 milliseconds before execution, the person can cancel the decision that has already been made.¹⁸
The long duration between the start of the signal and the actual execution of the decision ultimately serves to ensure that the “made” decision can still be stopped for a relatively long time. Many instances are actively involved in the process of inhibition, the prevention of a decision option.
Figuratively speaking, one area of the brain puts decisions “up for discussion” and gives other areas of the brain the opportunity to assess them and then allow or disallow them.

This checking and canceling mechanism is essentially controlled by dopamine. If the dopamine control circuit is disrupted, the mechanism used to abort decisions is impaired. Disorder of inhibition can be caused by dopamine levels that are too low or too high, so that the signal transmission is too weak or noisy, resulting in the attenuating (inhibitory, inhibitory) impulse not arriving.
The known disorder of the dopamine system explains the impulse control problems in ADHD.

3.1.2. Choice impulsivity: devaluation of distant rewards (delay aversion, reward discounting, choice impulsivity, CI)¶

Elective impulsivity (Temporal Reward Discounting) is a typical ADHD symptom^{1619 20} and includes:

• Devaluation of more distant rewards, while immediate rewards remain unchanged^21221423
  • Preference for immediate (small) rewards over more distant larger ones
  • Impaired ability to postpone reinforcement and reward
  • Devaluation of more distant rewards
  • All three forms are symptoms that occur not only in ADHD, but also in other disorders such as addiction or severe depression.²⁴
  • overlaps conceptually with
    • Impairment of decision-making
    • Delay aversion (temporal discounting, delay discounting, delay aversion). Delay discounting is the phenomenon in which a delayed outcome of a choice reduces the subjective value of a reward and reflects the operative measure of decision impulsivity.²⁵²⁶

Immediate reward and delayed reward are represented by different brain systems:²⁷

• Decisions on immediately available rewards:
  • Parts of the limbic system that are connected to the dopamine system of the midbrain, including the paralimbic cortex
• intertemporal decisions independent of the delay:
  • Regions of the lateral prefrontal cortex and posterior parietal cortex
• Decisions for longer-term options:
  • correlate with relatively greater fronto-parietal activity

A devaluation of delayed rewards is not only found in ADHD, but also in²⁸

• Addictive behavior (heroin addiction, cocaine addiction, alcohol addiction, opioid addiction, nicotine addiction),
• Bipolar Disorder
• Antisocial personality disorder
• Social anxiety disorder
• Borderline personality disorder
• Major depressive disorder
• Schizophrenia
• Schizoaffective disorders
• Pathological gambling
• Lesions of the orbitofrontal cortex

Impulsivity appears to result from the avoidance of negative affective states associated with delay. People with ADHD perceive a delay before (personally desired) outcomes or events as particularly aversive, which reinforces the motive to avoid this delay. Fittingly, in ADHD, the amygdala is hypersensitized to cues of delay (personally desired events).²⁹

ADHD appears to be related to suboptimal temporal decision making (as an example of inconsistency) rather than steeper delay discounting. High ADHD symptoms were not only associated with less frequent choice of the delayed option when it was better, but also with more frequent choice of the delayed option when it was not better. In addition, ADHD was associated with higher inconsistency in both cases.³⁰

The discounting of temporal rewards was more pronounced in people with ADHD-C than in ADHD-I or controls. However, the negative emotions related to waiting were equally strong. Thus, the choice of smaller but more readily available rewards was not determined by a stronger aversion to waiting, but by reduced inhibition. In other words, the choices in the person with ADHD-C were more in line with their feelings.³¹

Delay aversion and the preference for quicker and smaller rewards in ADHD is completely normalized by access to immediate visual stimuli during the waiting period.³²

Dopaminergic drugs, especially those that address DRD2 and DRD3, correlated with an increased preference for later rewards. Testosterone and cortisol led to more impulsive decisions (in the short term).²⁸

3.2. Impulse control problems / inhibition problems as ADHD symptoms¶

On the neurophysiological causes of impulsivity and inhibition problems ⇒ The neurophysiological correlates of inhibition and impulse control problems.

3.2.1. Manifestations of inhibition problems in children¶

• Often blurts out answers before the question is finished (DSM IV/5)
• Frequently interrupts and disturbs others (e.g. bursts into other people’s conversations or games) (DSM IV/5)
• Finds it difficult to wait his/her turn (DSM IV/5)
  Having difficulty waiting for one’s turn is not only seen as an impulsivity problem, but also as a problem of aversion to inactivity.

3.2.2. Manifestations of inhibition problems in adults¶

• Spontaneous, rash decisions
  This is one of the 9 most accurate symptoms of ADHD in adults, but³³ is also found in acute (hypo)manic people with ADHD or some Axis II problems.
  • Spontaneous purchases
    • Buying something without needing it
    • Buying something without reflecting on whether there is enough money for it
  • spontaneous acceptance / termination of a job
  • spontaneous beginning / spontaneous ending of a relationship
  • Unconcernedness in dangerous situations Whether this is actually an inhibition problem or rather a question of directing attention is an open question. As we understand it, in ADHD the control of attention follows the dictates of the stress maxim that there is a (survival) threatening, uncontrollable danger. This can lead to significantly different assessments of what is dangerous and what is not.
• Exuberant ideas must be communicated quickly before they are in danger of being forgotten³⁴
• Excessive cell phone use correlates with impulsivity³⁵ and affected 20.1% of the participating student test subjects.
  • Excessive cell phone use continued to correlate with higher levels of
    • Alcohol consumption
    • Sexual activity
    • PTSD/PTBS
    • Anxiety disorders
    • Depression
• Impulsivity in ADHD and increased BMI share genetic and neurophysiological correlates³⁶
• Speech is often perceived as aggressive by the environment

Impulsivity alone is not a compelling indication of ADHD. In a study of impulsive subjects with and without ADHD, people with ADHD showed a greater lack of interpersonal interaction, more indecisive decision-making, and lower motor skills than the non-ADHD subjects with and without impulsivity. Impulsivity without ADHD showed good motor skills, good 1:1 social interactions, good decision making in spatial orientation tasks, and more versatile laterality in the lower limbs.³⁷

3.2.3. Impulse control disorder as an extreme form¶

Impulse control disorder is a specific form of impulse problems. It is an independent psychiatric condition characterized by compulsive, impulsive behavior with impaired self-control.
The prevalence of impulse control disorder is 6.1%. People with ADHD have a prevalence of 19.6%, which is around 3.2 times higher.³⁸
People with ADHD are unable to resist their impulses. The decision to carry out the impulse action is made unconsciously. Impulse control disorders are typically subject to 5 phases:

• Impulse
• Growing tension
• Trading with pleasure
• Liberation from the urge
• Feelings of guilt (not mandatory)

Examples are mentioned:³⁹

• Gambling addiction (pathological gambling)
• Trichotillomania (pathological hair plucking)
• Kleptomania (pathological stealing)
• Pyromania (pathological arson)
• Intermittent explosive disorder (pathological irascibility)
• Hypersexuality
• Compulsory purchase
• Internet addiction
• Skin Picking Disorder

3.3. Impulse control problems as symptoms of stress¶

Impulsiveness can also be seen as an urgency to make decisions¹

Typical stress symptoms are known:

• Impulsiveness⁴⁰
• Riskier decisions⁴¹
• Decision-making problems⁴⁰⁴²⁴³

3.4. Increased willingness to take risks¶

Increased risk-taking is not a form of impulsivity, but has points of contact with impulsivity.

A distinction must also be made between risk-taking behavior and risky decisions when it comes to risk affinity.
While impulsive decision making involves a preference for small, immediate rewards over larger, delayed rewards, risky decision making is a preference for decisions with a higher variability of possible outcomes (preferring large uncertain rewards over small certain rewards).⁴⁴

3.4.1. Riskier decisions as an ADHD symptom¶

ADHD is associated with riskier choices.⁴⁵⁴⁴
According to one review, every other study found evidence of riskier decisions in children with ADHD, while risky decisions decreased in adults with ADHD.⁴⁶
One group of authors found no riskier decisions in ADHD, but riskier risk-taking behavior⁴⁷⁴⁸ , which was related to suboptimal decisions rather than an affinity for risk in decision-making⁴⁹⁵⁰ .

3.4.2. Increased risk behavior as an ADHD symptom¶

Studies⁵¹⁵² such as meta-analyses⁵³⁵⁴ , (meta-analysis, k = 115)⁵⁵ report a slightly to moderately increased risk behavior of people with ADHD.
A comprehensive study of 2,434 workers in Iran found a risk distribution of:

• Very low risk behavior (65.6%)
• Low risk behavior (27.8 %)
• Moderate risk behavior (4.1 %)
• High risk behavior (2.5 %)

ADHD increased the probability of belonging to the moderate or high risk behavior group by 3.4 and 3.1 times (+240%, +210%). An anxiety disorder increased the risk behavior by 2.1 and 2 times, respectively, compared to the probability of belonging to the lowest risk group.⁵⁶

Other sources saw no firm evidence of increased risk-taking among people with ADHD.⁵⁷⁵⁸

The increased risk behaviors in adolescents with ADHD included the positive behavior of prosocial risk taking.⁵⁹

In the case of SHR, stress experience in adolescence increases risk affinity in adulthood.⁶⁰

Students with ADHD showed significantly increased sexual risk behavior. ADHD medication reduced this.⁶¹
According to another study, ADHD medication reduced the incidence of unintentional injuries but not overall risk behaviors in children with ADHD.⁶²

We see increased risk behaviors, especially in externalizing ADHD subtypes.

Some people with ADHD enjoy high-risk sports (hang-gliding, bungee jumping, motocross, mountain biking).³⁴ It is possible that the concentration required or triggered by these activities could act as a positive hyperfocus
An increased willingness to take risks appears to correlate with spontaneous and impulsive decisions. However, the above-mentioned increased willingness to take risks in people with anxiety disorders could speak against this.

Increased risk-taking in ADHD is in tension with increased anxiety that is common in ADHD. These could be different forms of presentation.
The data from the (medically unvalidated) ADxS.org symptom test showed a correlation between the answers to the question “Do you often make riskier decisions?” with impulsivity (0.35), novelty seeking (0.34) and hyperactivity (0.26) in particular, but less so with inner restlessness or attention problems (0.19 in each case), while there was no correlation at all with the symptom anxiety (0.01) (as at January 2023, n = 19,000).

3.4.3. Increased willingness to take risks as a symptom of stress¶

Increased willingness to take risks can be a stress symptom of acute, short-term stress.⁶³ This increased willingness to take risks ended 40 to 80 minutes after the end of the stressful situation and then even decreased below the level of non-stressed persons.⁶⁴
This is in line with findings that chronic stress contributes to a reduction in the willingness to take risks.

An increased willingness to take risks is said to be a stress symptom in people who show a robust cortisol increase in response to an acute stressor. Young men without a clear cortisol response to a stressor did not show an increased willingness to take risks. This can be interpreted to mean that the stress response of increased risk-taking only occurs in those people who respond to stress with an increase in cortisol, or that the subjects in whom no increase in cortisol was measured in response to the TSST did not respond to it with stress.⁶⁵

3.5. Novelty Seeking / Sensation Seeking¶

Novelty seeking is not a form of impulsivity, but correlates with impulsivity⁶⁶

Novelty seeking is more common in ADHD.⁶⁷⁶⁶ Children with ADHD show increased novelty seeking.⁶⁸⁶⁹
SHR also show increased novelty seeking.⁷⁰

Novelty seeking is significantly more strongly associated with impulsivity and hyperactivity than with inattention.^76777866 Novelty seeking and hyperactivity/impulsivity have common genetic causes that explain 64% of the correlation. 12% of novelty seeking can be explained by hyperactive-impulsive behaviors.⁷⁹
According to the data from the (medically unvalidated) ADxS.org online symptom test (as of January 2023, n = 19,000), novelty seeking also correlated most strongly with impulsivity (0.27) and inner restlessness (0.25) and significantly more strongly with the externalizing ADHD subtypes (0.28) than with ADHD-I (0.04)

Novelty seeking is associated with the DRD4-7R gene variant, which is a candidate gene for ADHD.⁸⁰

3.6. Devaluation of later rewards (delay discounting / reward discounting)¶

Other names for “delay discounting” are “temporal discounting”, “intertemporal choice” or “impulsive choice” or “discounting of delayed rewards”.^8140828384

Devaluation of later rewards / delay discounting can be seen as a reversal of delay aversion (aversion to waiting, impatience). Both initially give the impression of a stress-related change in motivation. From the perspective of the functionality of stress symptoms, a devaluation of distant rewards could be translated as: Survival is now. Now is the time to defend oneself against relevant dangers, everything that is later is currently unimportant. Everything that is important must happen now. Anything that is not so important that it does not have to happen immediately can wait until the stressor is defeated.
In fact, however, delay discounting is probably a subtype of impulsivity.⁸⁵

3.6.1. Devaluation of later rewards as an ADHD symptom¶

People with ADHD often suffer from a reward deferral aversion: a smaller reward now is better than a bigger reward later.⁸⁵⁸⁶⁸⁷ This is compounded by inconsistent decision-making patterns.³⁰

For everyone, immediate rewards are intuitively more rewarding than delayed rewards. However, the decrease in the value of later, delayed rewards is significantly higher for people with ADHD than for non-affected people. While immediate rewards are rated the same by people with ADHD as by non-affected people, people with ADHD rate later rewards as significantly lower or less attractive than non-affected people.

However, the devaluation of distant rewards in ADHD is less related to motivational problems than to impulsivity. Impatience correlates very strongly with impulsivity and is therefore a phenotypic symptom of ADHD-HI and ADHD-C, but less so of ADHD-I. Impatience also correlates very strongly with impulsivity.

One study found 5 different profiles of delay aversion in ADHD:⁸⁸

• conventional: Reward discounting with normal increasing depreciation over the delay
• slightly steeper: as conventional, with slightly steeper depreciation
• steep discounting: abrupt devaluation of the reward
• flat discounting: weaker devaluation of remote reward
  • Hypoconnetivity between frontoparietal network and DMN
• Zero discounting: no devaluation over the delay period
  • Hypoconnetivity between frontoparietal network and DMN

Children with ADHD-C were subject to significantly greater discounting, while children with ADHD-I were subject to significantly weaker discounting than non-affected children:⁸⁸

	Steep	Slightly steeper	Normal	Flat	None
ADHD-C	20.1%	53.5%	26.4%	0.0%	0.0%
Not affected	20.8%	36.8%	23.6%	15.3%	3.5%
ADHD-I	16.7%	34.0%	7.6%	34.0%	7.6%

Manifestations of the preference for immediate rewards / devaluation of delayed rewards are:

• Addiction problems

• Procrastination
  The devaluation of tasks that are not immediately important is a related reaction.

3.6.2. Devaluation of later rewards as a stress symptom¶

Rewards that are immediate are valued by people with ADHD in the same way as by people without stress.
Rewards that are further away in time are seen as even less attractive than by people without stress.

Forms of expression:

• Procrastination
• Addictive tendencies
• Disorder
• Poorer ability to self-regulate
  • Self-regulation ability is an even better predictor of professional success than intelligence

Addiction problems are closely linked to the preference for immediate rewards. Mental or physical effort is not necessary to obtain the reward. The addictive substance leads to an immediate reward, e.g. relaxation. Addiction problems are typical symptoms of stress

• Drug / nicotine / alcohol abuse (addiction)⁹¹⁹²
• Smoking correlates with stress⁸²

3.7. Delay aversion¶

Delay aversion can be described as the mirror image of the devaluation of later rewards (delay discounting) and represents the opposite pole of procrastination in the sense of a regulatory disorder.
Delay aversion occurs in both children and adults with ADHD. Delay aversion is a persistent motivational deficit that can be reduced or eliminated by increasing subjective motivational incentives.⁹³

3.7.1. Delay aversion in ADHD¶

3.7.1.1. Impatience; waiting is perceived as unpleasant¶

• When others are slow to understand, it drives you crazy
• Parents get upset when their children are slow to understand homework³⁴
• Tasks are started without first listening to the instructions or reading the manual.
  This is one of the 9 most common symptoms of ADHD in adults⁹⁴
  • Operating instructions are read diagonally at best before commissioning devices
  • People don’t like to read furniture assembly instructions
• Particularly strong aversion to traffic jams, queues; up to the point that these can make them aggressive,³⁴ whereby the latter is probably less likely to affect the ADHD-I subtype
• Difficulties waiting for your turn
• Inner restlessness when you are not supposed to act yourself but accompany the actions of others
  • E.g. tendency to carry out tasks of others themselves instead of letting them do it (possibly slower / worse, because first learning)
• Tendency to interrupt others
• Answers are given before the question has been heard to the end
• Exuberant ideas must be communicated quickly before they are in danger of being forgotten³⁴
• Drive faster than others³⁴
  This is also one of the 9 most accurate symptoms of ADHD in adults.⁹⁴

The fact that boredom is perceived as extremely unpleasant is more likely to be due to dysphoria caused by inactivity

3.7.1.2. Correlation of delay aversion with other symptoms¶

According to the current data status of the ADxS symptom test (June 2020, n = 1,889), delay aversion does not appear to result solely from an inhibition problem, as is the case with impulsivity, but correlates significantly more strongly with inner restlessness and frustration intolerance than with impulsivity and than impulsivity with these. The correlation with emotional dysregulation also appears to be higher than with impulsivity
Interestingly, the correlation of procrastination aversion with procrastination appears to be significantly lower than with impulsivity and the correlation of procrastination with impulsivity is the same as with procrastination aversion.

Symptoms	Delay aversion / impatience	Impulsiveness
Inner restlessness	0.85	0.69
Frustration intolerance	0.79	0.57
Impulsiveness	0.67
Delay aversion / impatience		0.67
Reward deferral problems	0.58	0.46
Inability to recover	0.57	0.45
Inattention	0.56	0.53
Hyperactivity	0.55	0.59
increased sensitivity	0.53	0.43
Rejection sensitivity	0.53	0.41
Procrastination	0.34	0.34

As at June 2020. n = 1,889. The values given reflect the correlation of the symptoms relative to each other. This is a non-validated online self-test (screening).

3.7.2. Delay aversion as a stress symptom¶

Delay aversion is also understood as an impulsivity reaction. It correlates with impulsivity under stress and, in women, with an increasing heart rate.⁹⁵⁹⁶

Stress-reducing measures also reduce delay aversion.⁴⁰