Temperamental risk factors in young adults with ADHD symptoms


 
 Introduction: In recent years, numerous studies have focused on the analysis of the primary mechanisms and forms of therapy in children and adolescents with attention deficit hyperactivity disorder (ADHD). The analysis of such topics among similarly diagnosed young adults is only beginning to gain popularity. The present article attempts to answer the question of whether the level of individual temperament traits will predict an increase in the severity of ADHD symptoms in young adults.
 
 Materials and methods: The questionnaire study involved 111 young adults aged from 18 to 28 (M= 23; SD= 2.12; 70 women and 41 men). Fifty-one people were included in the clinical group, and sixty were qualified for the control one. The participants of the study completed a health questionnaire and a structured diagnostic interview on ADHD symptoms in adults (DIVA 2.0) and a questionnaire for the diagnosis of basic, biologically determined dimensions of human personality (FCZ-KT (R)).
 
 Results: The results indicate a significant role of four temperament traits that may be considered as specific risk factors for the aggravation of ADHD symptoms. These include briskness, rhythm, endurance and activity.
 
 Conclusions: In Strelau’s Regulatory Theory of Temperament, the variability of temperament traits (in the Polish population) is attributed in 44% to genetic factors. The remaining 56% indicate non-genetic factors. The obtained results may indicate which factors are important in therapeutic work both in the group of young adults with ADHD symptoms, and may also constitute a source of information for parents or teachers regarding younger children with these symptoms.


Introduction
In recent years, numerous studies have focused on the analysis of the primary mechanisms and forms of therapy in children and adolescents with attention deficit hyperactivity disorder (ADHD) [1,2,3,4,5]. The analysis of such topics among similarly diagnosed young adults is only beginning to gain popularity. Specialists' small interest in this issue was rooted partly in the belief that the symptoms which appear in childhood disappear later [6,7]. However, current studies show that these syndromes persist and that young adults with ADHD need support no less than children [7,8]. Taking into account the number of undiagnosed coexisting disorders, complications, and the often untreated attention deficit hyperactivity disorder in early adulthood, it becomes evident how much further research in the issue is necessary. This is emphasized by the fact that the heterogeneity of the clinical picture of ADHD is also influenced by individual traits of temperament [9]. They appear as early as in the first years of life and are associated with innate human neurobiological mechanisms [10]. Therefore, linking conditions such as attention deficit, hyperactivity, and impulsivity with neurobiological functioning leads to observing numerous and valid associations. Some researchers suggest that brain structures related to the anterior attention network may be related to executive abilities and temperament in patients with ADHD [11]. Others see the important role of nerve mediators, i.e., dopamine or serotonin [5,12]; e.g., in healthy children, the dopaminergic system reacts to the mere anticipation of reward, while in children with ADHD, this phenomenon does not occur [5]. People diagnosed with ADHD need a much stronger gratifying stimulus than just imagining it. It may also explain the difficulty with deferring gratification and being impulsive. The analysis of temperament allows not only to differentiate people in terms of behavioural characteristics and manner of reaction but may also provide a more complete understanding of their actions and an adequate selection of a therapeutic strategy.
Today, there are many definitions of temperament and its factors [13]. However, some features are commonly noticed [14,15]. Temperament is assumed to occur both in humans and animals. It is a component of the personality, in part genetically determined. It is observed from early childhood and is considered to be relatively constant [14,15,16]. Researchers indicate that the increase in the level of some temperament traits may contribute to the disturbed functioning of an individual [17,18]. One of the first studies on the relationship between behaviour disorders and temperament was carried out in 1956 by psychiatrists Thomas and Chest [17]. The researchers concluded that the temperament classified as difficult may influence the occurrence of behavioural disorders [13,14]. They characterized it as: a tendency to withdraw and not adapt to the prevailing rules (e.g. not responding to an adults' commands), excessive emotionality and hyperactivity, frequent lack of regularity in undertaken activities, and a predominance of negative emotional reactions during the day [17]. Subsequent analyses confirmed the relationship between difficult temperament and the occurrence of behavioural disorders [19]. They showed that parents of children diagnosed with ADHD noticed many more features classified as difficult temperament in their children than parents of children from the control group. Similarly interesting results have also been obtained from other studies, which concerned temperament differences between children diagnosed with ADHD and without developmental disorders. The level of temperament traits was determined by the parents and teachers surveyed with the use of the EAS questionnaire. Among children with ADHD, higher levels of emotionality and slightly higher sociability have been reported. In both groups, the activity aspect remained at a similar, above-average level, although initially, the authors of the studies assumed its much higher levels in children with diagnosed ADHD [20].
The mentioned studies have a long history and focus on the relationship between temperament traits and ADHD symptoms in children. This article will explore the temperamental characteristics and symptoms of ADHD in young adults. The opinion of researchers such as Suat et al. [6], who observe a small number of similar analyses among people in this group, is worth focusing. In the Regulatory Theory of Temperament, Strelau points out that temperament manifests itself through formal behavioral traits, which include briskness, persistence, sensory sensitivity, emotional reactivity, endurance and activity. They play an important role in regulating human relations with his immediate environment [13]. This is important because early adulthood is a dynamic time where many changes usually take place. The context in which people with ADHD grow up is important for their later functioning [22].
The present article attempts to answer the question of whether the level of individual temperament traits will predict an increase in the severity of ADHD symptoms in young adults.

Material and method
The questionnaire study involved 111 young adults aged from 18 to 28 (M= 23; SD= 2.12; 70 women and 41 men). Nearly half of the respondents (45.6%) came from a city with up to 400,000 inhabitants. The smallest number of people declared that they came from towns of up to 150,000 residents (14.4%), while people from rural areas and towns up to 50,000 inhabitants were equal in number (19.8% each). Most of the people who applied for the study were at that time students in various fields of study throughout Poland (75.9%). The remaining participants had primary (0.9%), secondary (9.8%), and higher (12.5%) education. Fifty-one people were included in the clinical group and sixty were qualified for the control group. As many as 92.6% of the study participants did not report any additional diseases. In the remaining cases, mainly allergies and asthma were noted. The medications taken by the respondents were neutral for the study; therefore the results obtained from them were included in further analyses. In order to control the variables that could influence the experienced symptoms, subjects were asked to write down significant events in their lives that could affect their ADHD symptoms. Most of the respondents (92%) did not report such incidents. The Chi-square test analysis excludes the correlation between the number of diseases, medications and life events and the symptoms of ADHD or their absence in the respondents (respectively: The research was conducted using the correspondence method. On the official fan page of the Empirical ADHD Research Team, a published poster invited young adults experiencing difficulties related to attention deficit, hyperactivity, and impulsivity (ADHD) to participate in the study (https://www.facebook.com/901642126613041/ photos/a.913175842126336/2596337500476820/). The same procedure was subsequently used to find group of young adults without these symptoms. People qualified for the research took part in it voluntarily and during the e-mail correspondence they gave their consent to both the anonymous research and the subsequent publication of the collected results. This strategy of recruiting young adults with ADHD symptoms via social media was modelled on the procedure of researchers who, with the help of local media, also tried to reach this group of respondents (targeted randomization) [23]. The entire project was approved by the Scientific Research Ethics Committee of the Institute of Psychology of the Catholic University of Lublin (KEBN_26 / 2020).
The participants of the study completed the health questionnaire and the structured ADHD Diagnostic Interview for adults (DIVA 2.0) and the questionnaire for the diagnosis of basic, biologically determined dimensions of human personality -Formal Characteristics of Behavior -Temperament Questionnaire (FCZ -KT (R)).
The DIVA 2.0 questionnaire is a structured diagnostic interview based on ADHD criteria, intended for adults [24]. It is used both in clinical practice and in scientific research alongside such tools as the Conners' ADHD Symptom Scale (CAADID) or the Wender Scale (WURS) [25]. This tool allows for the diagnosis of ADHD in adults who did not have a formal diagnosis before [36]. The questions contained in it refer to both the current life situation and the symptoms that appear in childhood. The analysis of psychometric parameters has shown that it is a reliable and accurate tool [25]. The examined person performs self-description by responding to specific situations or behaviors. In order to determine whether a young adult can be diagnosed with ADHD, he should meet at least 4 criteria (out of 9 possible) appearing both in childhood and in adulthood -for attention disorders (8) and hyperactivity / impulsivity (8), respectively. The fulfilment of the above criteria regarding the presence of ADHD syndromes constituted the final inclusion in the clinical group. In addition to the criterion symptoms, the severity of individual symptoms can also be calculated, which can range from 0 to 55 for the attention disorders scale and from 0 to 44 for the hyperactivity / impulsivity scale. Each of the scales also has 9 open-ended questions defined as other symptoms.
The FCZ-KT (R) questionnaire is used to diagnose the basic, biologically determined dimensions of human personality. It has seven dimensions that can be used to describe temperament (briskness, perseverance, sensory sensitivity, endurance, emotional reactivity and activity, as well as rhythmicity) [26]. The tool consists of 100 items to which a person responds on a scale from 1 (strongly disagree) to 4 (strongly agree). The analysis of the psychometric properties of this tool turned out to be satisfactory both in terms of high reliability and validity [26,27].

Calculation strategy
At the beginning, the descriptive characteristics of the obtained results for the measured variables were made. There is a statistically significant difference in the higher mean intensity of attention disorders (t (73.56) 10.82; p = 0.001), hyperactivity and impulsivity (t (65.75) 9.24; p = 0.001) and the sum of ADHD symptoms (t (69.62) 10.92; p = 0.001) in young adults enrolled in the clinical group than in their control peers. There were also statistically significant differences in the mean intensity of activity (t (109) 4.45; p = 0. The results of the correlation analysis (Tab. 2) indicate a statistically significant negative correlation between the symptoms of disturbed attention in young adults and rhythmicity (r -0.308; p = 0.001), endurance (r -0.326; p = 0.001), and activity (r -0.361; p = 0.001) and a statistically significant positive correlation between attention disorders in young adults and perseverance (r -0.297; p = 0.002) and emotional reactivity (r -0.232; p = 0.014). There was no statistically significant correlation for the values of alertness and sensory sensitivity. The relationships for the symptoms of hyperactivity and impulsiveness are very similar. There is a statistically significant negative correlation between these symptoms and rhythmicity (r -0.304; p = 0.001), endurance (r -0.288; p = 0.001) and activity (r -0.298; p = 0.001), and a statistically significant positive relationship between psychomotor hyperactivity and impulsivity in young adults and perseverance (r -0.227; p = 0.002).
The last stage of the analysis of the obtained results was to determine the probability of the influence of temperament factors on the severity of ADHD symptoms in the group of young adults. Seven temperament factors were introduced into the tested model. The Hosmer-Lemeshow goodness-of-fit test indicates that the data is well fitted to the model (χ2 (8 ) = 3.660; p=0.886) (Tab.3). The conducted calculations show that only four temperament traits may be considered risk factors contributing to the possible increase in the severity The study assessed whether there is a relationship between temperament traits and ADHD symptoms (hyperactivity/impulsivity and attention disorders) in young adults with these symptoms, as well as whether the risk of aggravation of ADHD symptoms in young adults increases with the the increasing level of temperamental traits by one standard deviation. For this purpose, in the first step, Pearson's r correlation analysis was used, and With an increase in briskness by one unit of standard deviation, the ADHD symptom coefficient increases 1.104 times. This indicates an increase in the risk of worsening ADHD symptoms by 10.4% in young adults in the clinical group. The value of the ADHD coefficient (Exp (B) = 0.856) also increases when the intensity of rhythmicity decreases by one standard deviation unit in young adults. Then the risk of symptoms worsening in young adults may increase by 14%. On the other hand, as the strength of endurance decreases by one unit of standard deviation, the value of the ADHD coefficient increases 0.911 times. This indicates an increase in the risk of worsening ADHD symptoms by 8.9% in young adults in the clinical group. The last factor that proved to significantly explain the severity of ADHD symptoms in

Results
The growing interest of researchers in the problem of young adults with ADHD may contribute to more complete analysis of this phenomenon. This is emphasized by the fact that modern standards of clinical practice encourage the use of evidence-based medicine (EBM). Thanks to this approach, the scope of therapeutic activities is broadened, going beyond only the specialist's experience, and also focusing on reliable data derived from scientific research [3].
The obtained results indicate a significant role of four temperament traits that may be considered as specific risk factors for the aggravation of ADHD symptoms. These include briskness, rhythm, endurance and activity.
In the Regulatory Theory of Temperament, briskness and rhythmicity are among the temporal characteristics of an individual's behaviour. The first dimension reflects the course of the reaction in a given time [13,27]. This means that the more alert a person is, the faster he or she reacts to stimuli or other requirements of the external environment. Fast reaction times are most often associated with low levels of reflexivity, impulsiveness, lack of planning ability and a propensity to take risks [10,28]. Despite the consensus regarding the biological basis of temperament factors, it is noted that they are also susceptible to environmental influences. The research of Langer et. al shows that it is easy to arouse the person's state of mindlessness, which makes him or her more docile and less resistant to manipulation and that reflexivity can be trained. Strengthening this factor increases resistance to social influence [29].
Rhythmicity, on the other hand, is understood as the tendency to regularly perform activities related to the sleep-wake cycle, eating meals, and lifestyle. The present study demonstrates that the risk of aggravating ADHD symptoms in young adults increases with the decrease in the level of rhythmicity. Consequently, there is a certain regularity in the activities undertaken in the field of sleep, wakefulness and eating [13,27]. The results obtained in the present research correspond to the studies by Thomas and Chest and are also consistent with later studies on a group of children with ADHD [17,19]. From the point of view of biology, the results point to the role of serotonin, which regulates the functioning of the whole organism. Serotonin controls heart rate, muscle tone, and vascular contractility, but is also responsible for stabilizing mood, sleep, appetite, and aggressive behaviour [30]. In the pharmacotherapy of ADHD, drugs from the group of tricyclic antidepressants are often used. They allow the inhibition of serotonin reuptake and an increase in the concentration of neurotransmitters that stimulate receptors. As a result, patients with ADHD are able to maintain their attention longer and be less hyperactive [31]. Rhythmicity does not have a solely biological basis; it is also noted that it is an area of conscious psychological work. Experts indicate that impulsive eating or disorganized (non-rhythmic) eating habits (overeating at night) may be at the root of the difficulties in ADHD patients with coexisting obesity [32]. Such patients most often undertake cognitive-behavioural therapy in order to understand their difficulties and develop healthy habits [32]. Therefore, learning to be rhythmic, systematic and endurable in undertaken actions seems to be crucial.
In the present study, endurance is the third factor whose low level predicts the severity of ADHD symptoms. According to the Regulatory Theory of Temperament, it is a predisposition to react adequately in situations requiring a long-term effort. People with high endurance exhibit a tendency to high resistance to distractors and show less fatigue during intensively stimulating activities [13,27]. The results obtained in this study are consistent with the reports commonly found in the literature [33,34]. Importantly, low endurance is recognized as one of the four factors that describe impulsivity. The others include urgency (understood as a predisposition to act on the basis of strong impulses), low reflexivity (inability to predict the consequences of one's actions), and a strong need for impressions (searching for strong, exciting impulses) [33].
The last temperament factor that significantly predicts the risk of ADHD is activity. In the Regulatory Theory of Temperament, active people are referred to as organizers who look for both work and leisure conditions. They strive for social stimulation and also look for numerous intense and difficult activities [27]. The results obtained in this study indicate that a decline in the level of activity in young adults will predict the risk of aggravating ADHD. It must be admitted that the decline in activity as a temperament risk factor is intriguing and proved to be surprising for the authors of the study. Excessive activity is the first noticeable symptom of ADHD in a child's development [20,35]. Research on temperament among children and adolescents indicates the average and high intensity of this trait, which is assessed by parents and teachers [20]. Therefore, why is it precisely the decline in activity among young adults that predicts the severity of ADHD symptoms? Bobkowicz-Lewartoska and Giers observe that activity consists of two components (endurance and vigour -close in its meaning to briskness). This indicates that activity is a complex construct, especially in the area of low endurance, the inability to maintain the initiated activity at work as well as during rest, which are both challenging for people with ADHD. Recent studies on self-efficacy and persistence in boys with ADHD shed some more light on these dimensions [34]. The general sense of self-efficacy in this group is decreased with regard to persistence. The authors of the abovementioned studies claim that such results stem from the lower consistency of hyperactive boys in the implementation of the undertaken action and their greater ease in succumbing to discouragement [34]. Perhaps a similar phenomenon occurs among young adults. If there is a decline in activity, corresponding to low self-efficacy regarding the persistence in finalizing one's actions, it may explain the risk of worsening of ADHD symptoms in the future. Podgórska-Jachnik explicitly indicates that psychosocial factors may be a significant stimulus modifying the severity of ADHD symptoms [22].
Although temperament in its nature is relatively stable and biologically conditioned, it does not completely determine a person and his or her actions. In Strelau's Regulatory Theory of Temperament, the variability of temperament traits (in the Polish population) is attributed in 44% to genetic factors. The remaining 56% indicate non-genetic factors. These data indicate that environmental influences play a significant role in shaping the behaviour of an individual during his or her life.
In summary, selected temperament traits are related to ADHD symptoms and their severity. The obtained results may indicate which factors are important in therapeutic work both in the group of young adults with ADHD symptoms, and may also constitute a source of information for parents or teachers regarding younger children with these symptoms.