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8.1. Increased sensitivity / stimulus filter too wide open¶
In the following we speak of heightened sensitivity. High sensitivity, on the other hand, is a construct by Aron (validated only to a limited extent so far), which includes further elements beyond heightened sensitivity (in particular a certain form of perception / perception processing), which does not play a role here.
8.1.1. Increased sensitivity / too wide open stimulus filter as an ADHD symptom¶
Stimulus openness1 is a symptom of ADHD, which has sometimes also been called stimulus filter weakness. However, this name only refers to a part of ADHD.
Maladaptive reactivity to sensory input is commonly observed in neurodevelopmental disorders such as ADHD or ASD.23 ADHD sufferers suffer from overload - they perceive incoming stimuli, especially visual, acoustic and tactile stimuli, to an increased degree. Normal environmental stimuli stress them so much that they cannot filter out background noise4
ADHD is almost always associated with increased sensitivity. In our ADxS online symptom test, 87% of 200 diagnosed ADHD sufferers showed signs of increased sensitivity. This was similar to the score for attention problems, so it is very high. Increased sensitivity is increased perceptual intensity. Other studies also found a correlation of increased sensitivity with ADHD symptoms and also with lower quality of life,5 although increased sensitivity in ADHD is often associated with comorbid ODD or anxiety and exists regardless of subtype.6 A review of nearly 1900 records from the ADxS online symptom test (as of June 2020) also found that increased sensitivity correlated with ADHD-HI to the same degree as ADHD-I. Interestingly, another study found a correlation of SOR (Sensory-Over-Responsivity) in ADHD with an elevated cortisol stress response (which we believe is more common in the ADHD-I subtype), while non-SOR ADHD sufferers showed a flattened cortisol stress response (as we believe is more common in ADHD-HI). SOR was not associated with specific externalizing behaviors but was associated with sensory stimulus avoidance.7 Another study also found increased sensitivity in adult ADHD sufferers.8
ADHD shares with heightened sensitivity the too-wide-open stimulus filter, which is likely controlled by the thalamus.
Noise / sound sensitivity
Feelings of others transfer
Feel moods of others unpleasantly intense
Can easily make you cry
Do not like to watch (certain) movies because of too intense sensations
Perceive tastes / smells more intensively
This is said to correlate (independently of ADHD) with an increased sensitivity in the selection of preferred foods9
Rough fabrics are unpleasant
Special sensitivity to high or low temperatures
Want to change the temperature earlier than others
Hypoglycemia / hunger / thirst is difficult to bear
Less frequent than other characteristics
In particular, increased tactile sensitivity in ADHD was reported to correlate with increased anxiety.10 Furthermore, a correlation between SOR and anxiety was found.11
About half of all ADHD sufferers also meet the criteria of the Sensory-Over-Responsivity Test.1210 To this end, it was hypothesized that SOR might correlate with GABA deficiency
Compared to non-affected individuals, children with both ADHD and ASD showed increased stimulus sensitivity. While ASD showed higher oral stimulus processing than ADHD, ADHD was associated with higher visual stimulus processing than ASD. Stimulus sensitivity decreased with age in all groups. ADHD was found to have aberrant patterns of sensory stimulus perception and processing:13
Are more likely to search for sensory input (search patterns)
Are more aware of sensory stimuli (sensory patterns)
Are more easily disturbed by certain stimuli (avoidance patterns)
Perceive sensory stimuli more weakly (lower registration/caregiver pattern)
Children with ADHD show increased sensory sensitivity and have problems in proprioception, vision, auditory and tactile sensory processing. These sensory processing deficits are associated with functional, social, behavioral, and learning difficulties.14
8.1.2. Increased sensitivity and correlation with ADHD subtypes¶
In the analysis of almost 1900 records of the ADxS.org symptom test, increased sensitivity correlates in total with ADHD-HI as well as ADHD-I to the same extent (0.50 to 0.51). If the individual sub-areas of sensitivity are considered separately, there are indications of different correlations with the subtypes:
Correlation with ADHD-HI and ADHD-C
Correlation with ADHD-I
rough materials unpleasant
Mood of others transmits
Cannot tune out side table conversations
Can’t ignore TV in pub
Total distractibility (for comparison)
The question on temperature sensitivity was aimed at whether one was one of the first to want a change in temperature. This involves willingness of expression over and above sensation, which is likely to influence the result. This is a non-validated online self-test (screening).
8.1.3. Increased sensitivity as a symptom of stress¶
A (stress-induced) elevated norepinephrine level immediately triggers increased perceptual sensitivity.15 The noradrenaline increase is mediated by the nucleus coeruleus.16 The nucleus coeruleus is activated (among other things) by stress and in turn activates other stress systems such as the sympathetic nervous system.17 Consequently, increased sensitivity is also a possible symptom of stress.18
Empathy is the ability to empathize with other people. It consists of emotion recognition, cognitive and affective empathy. For emotion recognition, see there.
There are different concepts that describe how empathy arises. The multidimensional empathy concept distinguishes between cognitive empathy (the understanding of the emotional states of others, similar to the Theory of Mind) and emotional empathy (the emotional reaction to the state of mind of others) 22 Comorbid PTSD or intrusions may reduce cognitive empathy. 22
Emotion recognition is a subset of empathy23 and refers to the ability to recognize emotions based on speech, facial expression, or behavior.24
Children with AD(HS, ASD, or language development disorder showed a similar developmental delay with respect to emotion recognition skills.25 Boys with ADHD showed aberrant brain activity in perceiving faces of family members.26 Another study confirmed poorer recognition of emotions in faces in ADHD sufferers.27
A metastudy found in 16 of 17 studies that ADHD children and adolescents show difficulty processing emotional information conveyed by visual scenes.28
That ADHD appears to alter the perception of emotion in shown faces, even when individuals no longer receive an ADHD diagnosis in adulthood,29 may be an interesting aspect to the alteration of empathy in ADHD
Similarly, people with disorganized attachment style showed a decreased ability to read emotions from faces, which correlated more strongly with ODD than with ADHD. This correlated with increased emotional reactivity at the same time.30 This is somewhat similar to a pattern known in borderline
This seems to contrast with our data from the ADxS.org symptom test on the question “Do you sometimes find others’ moods unpleasantly intense?”, which was answered in the affirmative significantly more often by ADHD sufferers than by non-affected persons. On a 5-point scale (-2 quite a little, -1 rather a little, 0 neither, 1 rather clearly, 2 quite clearly), ADHD sufferers scored an average of 1.0, and nonaffected people scored an average of 0.4. (n = 1889, as of June 2020). On closer inspection, however, a distinction should probably be made between the ability to recognize the emotions of others and self-discrimination against the emotions of others (which is the aim of the question in the symptom test).
One study (with only 30 subjects) found a reduced empathy capacity in ADHD.31 Other sources speak of an increased empathy capacity in ADHD.32
According to our impression, the ability to empathize often seems to be impaired in ADHD, but not fundamentally disturbed
Rather, it seems ADHD sufferers often cannot access or use their empathy skills
That the empathic ability is not non-existent in ADHD, but rather buried, is shown in 1:1 encounters in quiet surroundings or in hyperfocus - e.g. when in love. Sufferers of ADHD-HI and ADHD-C are also described here as very charming, empathic, and accommodating. This may seem different for individual sufferers, especially with an existing comorbidity from the aggression spectrum. However, this seems to be rather due to the comorbidity.
There are reports of strikingly high μ-frequencies in the EEG of ADHD patients.33 This high activity of brain waves in the μ-frequency range is representative for an underfunction of the mirror neurons, which are responsible for the ability to empathize with a counterpart. The phenomenon of a lack of μ-frequency suppression when observing others also occurs in autistic people (mirror neuron hypothesis).34
μ-rhythms could be suppressed by fist clenching. However, to date, fist clenching has not been observed to influence empathy ability in ADHD or in the unaffected. Therefore, μ-fist activity appears to be correlationally rather than causally related to empathy ability. In addition, data from the ADxS.org symptom test show that the statement “Moods of others transfer to me” is significantly more true in ADHD than in nonaffected individuals. This also contradicts the assumption that the ability to empathize would be impaired in ADHD per se.
8.2.3. Empathy exercise-especially in ADHD-HI subtype-impaired?¶
Thus, it seems to be less due to a lack of “technical” ability to empathize, but rather that the exercise of empathy is buried by other things (inner turmoil, sensory overload). Nevertheless, a reduced exercise of empathy is a symptom that is common in ADHD. Our (subjective) impression is that decreased empathy (exercise) is more common in ADHD-HI sufferers and increased empathy is more common in ADHD-I sufferers. The hyperactive/impulsive ADHD-HI and ADHD-C sufferers often appear to the outside world to have little empathy. What is certain is that ADHD is almost always associated with increased sensitivity. In our online survey, we found signs of increased sensitivity in 87% of 200 diagnosed ADHD sufferers. This is similar to the score for attention problems, so it is very high. Increased sensitivity is a more intense perception of external stimuli. Empathy is being intensely sympathetic to the sensations of others. The data on the correlation of individual parts of heightened sensitivity with the ADHD subtypes (see above under heightened sensitivity) indicate that the statement “Moods of others transfer to me” is significantly more true in ADHD than in non-affected persons, with this even affecting the ADHD-HI subtype a tiny bit more than the ADHD-I subtype, which could indicate that the subtypes are at least equally capable of empathy.
The worse off a person is, the higher his inner tension or anxiety, the higher the stress level, the lower the empathy shown.35 This could be considered a fairly healthy stress response: When it comes to survival, everyone is next to themselves. Once the stress, the anxiety is gone, it is again possible to feel for others. Findings that blocking glucocorticoid receptors increases empathy also point in this direction.36 In conjunction with a study in which ADHD-affected children showed a flattened cortisol response to the TSST, the more they exhibited psychopathic traits (callous unemotional traits = CU traits) such as lack of empathy, coldness of feeling, etc., and with other studies, the more they showed a flattened cortisol response to the TSST. 37 as well as other studies that also found a correlation of callous unemotional traits with externalizing symptoms3839 or with impulsivity40 in ADHD, suggests that a flattened cortisol stress response, as is common in ADHD-HI, is associated with a lower empathy capacity, so that a distinction would have to be made between the subtypes.
The permanent inner overactivation in ADHD-HI subtypes, the permanent inner restlessness (which, according to the data of the ADxS-Online-Symptomtest, shows itself in a strongly increased inability to recover in ADHD-HI, which is also increased in ADHD-I compared to non-affected persons, but not as strongly as in ADHD-HI) seems to demand so many resources of the affected persons that they can hardly exercise their - actually existing, although sometimes also untrained due to lack of use - ability to empathize. ADHD-I sufferers, on the other hand, seem to be able to exercise their empathic abilities to a special degree. It is conceivable that this is less a consequence of different personality aspects in ADHD-HI and ADHD-I, but rather that this results from the fact that ADHD-HI is characterized by a chronically activated HPA axis (due to a lack of recovery ability because of a typically flattened cortisol stress response, unable to shut down the HPA axis), whereas ADHD-I is characterized by an exaggerated endocrine stress response whose high cortisol stress response reliably shuts down stress-induced activation of the HPA axis. These endocrinological patterns, to our understanding, could potentially explain differential empathy frequency in ADHD-HI and ADHD-I.
This is consistent with research findings on PTSD/PTSD, which suggest that communication between the cerebral hemispheres is essential for emotion recognition and processing. This communication between the cerebral hemispheres is functionally disrupted in PTSD/PTSD without an anatomical disruption of communication, as in a severance of the corpus callosum, which is required as ultima ratio in epilepsy and also leads to alexithymic behaviors.41 In states of strong emotional or cognitive stress, even in neurologically intact people, events in the right hemisphere are functionally separated from the left by inhibition of transmission between the cerebral hemispheres 42
Further, early childhood stress is arguably associated with reduced emotional empathy, but not reduced cognitive empathy.43
That acute pain tends to increase empathy could be an interesting aspect in relation to self-injury behavior in borderline.4445 Then, a distinction could be made between short-term stress (empathy increasing) and chronic stress (empathy decreasing). Thus, even in rats, empathy is increased during low acute pain stress, whereas it is decreased during severe pain stress.46
See also: Brain hemispheres in AD(H)D.
8.3. Time perception problems in ADHD (chronasthenia)¶
In ADHD, the perception of time is very often disturbed.
Barkley47 sees time perception problems as a separate and significant symptom of ADHD. Studies report that ADHD sufferers are worse at estimating how long it will take them to complete a task - and subsequently, what they can accomplish within a period of time. Under medication, this normalizes.48 No differences were found between ADHD subtypes.49 Time perception and time processing problems affect children as well as adults with ADHD50 and are already an indication of possible ADHD in preschool children.51
Time perception problems often cause a frustrating negative perception of one’s own performance, which could thus, at least in part, merely represent a consequential error of faulty time perception. This in turn reinforces a negative self-perception. (See also: Performance problems as an ADHD symptom)
Altered perception of time as a stress benefit?
Changing time perception could be a stress benefit. In acute danger, it is useful to prioritize things that are not necessary for survival as less important. Changing time perception could support prioritization of things necessary for survival. See more at ⇒ Stress utility-the survival purpose of stress
An individual who is in acute danger (survival-threatening stress) has a greater chance of survival if he or she treats all things farther away as less important and all things immediately at hand as more important. Since anything further away is not as important in the emergency mode of the survival program, it may also be less important to be able to accurately estimate the temporal distance and time requirements of more distant tasks.
Highly industrialized countries’ understanding of time as a contributory cause?
Rossi52 notes that the understanding of time in the highly industrialized countries is very strict for cultural reasons. Even in highly developed Mediterranean countries, one encounters a different understanding of time than in Germany or the USA. This is all the more true for large parts of the world. He therefore questions whether this is really already a pathological symptom.
However, since it has been empirically proven that ADHD sufferers are significantly more likely to have time perception and scheduling problems than other members of the same cultural group, the phenomenon is definitely a relevant ADHD problem and not a matter of cultural group fit ADHD also occurs in the countries mentioned by Rossi with such a different perception of time.
At the same time, Rossi himself cites a lack of sense of time as a symptom of ADHD-I (without hyperactivity).53
In ADHD, the ability to estimate how much time an action or task will take is limited.545556
ADHD sufferers are less able to estimate longer time intervals than non-affected individuals.
Finish work too late
Constant late arrival
Time estimation error
Waiting is unbearable (Delay Aversion)
Waiting is rest and inactivity (resulting in dysphoria when inactive)
Every living being controls itself centrally to keep the mood as good as possible
The time until X is fully utilized for activities. Since something usually goes wrong, and time estimation is a problem with ADHD, those affected often arrive too late. It is better to do this or that quickly than to run the risk of arriving too early and then having to wait. The result is frequent tardiness.
Now is always
The perception of what is important is shifted towards the present
For interesting things / work, time passes extremely fast, it feels like
Others are kept waiting
As a result, others feel disrespected (even if that was not the person’s motive) and understandably react in a rejecting manner. This triggers the already miniaturized self-esteem of the affected person.
To distinguish the length of two time intervals, one of which lasted 1 second, the other had to last 1.184 seconds for non-affected individuals, while this one had to last 1.238 seconds for ADHD sufferers, thus being 30% longer.57 Other studies have come to similar conclusions.58 In ADHD, the ability to reproduce a time interval in the correct length is further impaired. This impairment correlates with impulsivity.59
Perception of time in ADHD focused on present and positive future?
8.3.3. Perception of time in ADHD focused on present / positive future?¶
There are still too few studies on this aspect to be able to make a reliable statement with regard to ADHD.
Several studies have addressed individual differences in time perception, especially the distribution of attention among time perspectives such as future, past, and present.60 One standard for assessing time perspective is the Zimbardo Time Perspective Inventory (ZTPI). The ZTPI estimates the intensity with which perceptions focus on the past, present, and future and whether time perspective tends to be perceived positively or negatively.48 Several types of disorders can be attributed to imbalances in time perception.
As mentioned at the beginning, there are still too few studies on this aspect in relation to ADHD to be able to make a reliable statement.
One (as yet unverified) thought on this is that an altered perception of time in the sense of a present focus (in the sense of a perceived “now is always”) could intensify the subjective perception of stress through increased helplessness. If there is a lack of perspective that an unpleasant condition, a pain, will also pass, this is likely to significantly increase the subjective distress caused by this perception. This could help explain the increased subjective perception of stress in ADHD.
8.4. Chronic pain, increased sensitivity to pain in ADHD¶
ADHD sufferers often show increased sensitivity to pain. MPH can address this pain sensitivity in ADHD sufferers.6768 High ADHD scores correlated with increased pain69
Similar symptoms include increased sensitivity to stress and increased sensitivity to punishment. See Emotional dysregulation.
Of 77 adult women with ADHD or ASD, 76% each reported chronic pain.70Chronic widespread pain (CWP), the main symptom of fibromyalgia, was almost twice as common in ADHD as in ASD, at 39%.
The most frequently mentioned painful body regions were
Lower back (47 %)
Neck (37 %)
Shoulder (35 %)
Head (32%, related to ADHD)
Stomach (30 %)
Arms / Hands (30 %)
Upper back (27 %)
Knee (27 %)
Hip / Thigh (18 %)
Calves / feet (16 %)
Breast (4 %)
Increased pain sensitivity was observed in 6-OHDA mice in which dopamine synthesis is chemically damaged, thereby providing an ADHD animal model. Pain sensitivity was thought to be mediated by α- and β-adrenergic and D2/D3 receptors. Atomoxetine was able to reduce pain sensitivity.71