After-effects of hyperkinetic disorder (HKD) in prospective longitudinal (12 years) study

PURPOSE

The phenotype including three domains, i.e. impulsivity, hyperactivity and inattention, is classified according to ICD-10 [1] as hyperkinetic disorder (HKD), which is referred to as a subset of attention deficit hyperactivity disorder (ADHD) by DSM-IV [2] and DSM-V [3]. Due to the rigorous criteria, prevalence of HKD is estimated to be approximately 1-2% in school-age population [4]. Hyperkinetic disorder is a chronic neurodevelopmental disorder which hampers the child’s developmental and adaptation processes and causes educational failures. Furthermore, it predisposes children to other psychopathological and social dysfunctions. Despite extensive research, the causative treatment continues to be unknown. Symptoms of inattention and impulsivity persist in adolescence and adulthood in a significant proportion of patients [5, 6]. They constitute a high risk of the occurrence of behavioural disturbances, delinquencies, psychoactive substances abuse, lack of education, unemployment, minor offences and traffic accidents [7-11].
So far, research has focused mainly on the course of attention-deficit hyperactivity disorder. The persisting repetitive patterns of antisocial behaviours meeting the criteria for conduct disorder in ICD-10 or DSM-IV/V are also the adverse consequence of ADHD [7, 9, 12, 13]. On the other hand, high incidence of affective disorders and anxiety disorders was found in adolescent and adult patients with ADHD diagnosed in childhood [14-17]. The phenotype of HKD in childhood seems important for both internalizing and externalizing disorders in adults. Internalizing disorders consist, according to the DSM-V Task Force (premature scientifically to propose alternative definitions for most disorders) of anxiety and depressed mood, however, the externalizing group is characterized by antisocial behaviours, conduct disturbances, addictions and impulse-control disorders [3].
Risk factors responsible for transition from HKD to so diverse disorders are still unclear. Therefore, the aim of this study was to evaluate the associations between HKD in childhood and psychopathology of young adults in prospective study. The author hypo¬ thesized that the longitudinal observation of the same group of children with homogeneous phenotype may allow to identify the determinants of adverse course of HKD.

METHODS

Participants and procedure

The research was carried out between 2002 and 2014. The study included 54 children with HKD symptoms (95.1% male); mean age of this group at the moment the study was launched was 8.1 years (SD ± 1.7). The consequences of hyperkinetic disorder were assessed more or less after 12 years of observation, when the care at the Psychiatric Outpatient Department was over (mean age of participants: 19.1 years; SD ± 1.7). Research report prepared at this point of the study for each child included data on the family structure, parents’ education, conflicts, mental illness and substance abuse in the family as well as pregnancy, gestational age at birth (weeks), birth complications, weight at birth, Apgar score, coherence and consistency in the child care. The diagnosis of HDK, which was performed according to the criteria of ICD-10 [1], requires the symptoms of three domains (at least 6 of 9 items of inattention; at least 3 of 5 items of hyperactive and at least 1 of 4 of impulsivity). Severity of the disorder was measured by using the Polish version (authorized translation) of NICHQ Vanderbilt Assessment Scale for Parent (VADPRS) and for Teacher (VADTRS) [18]. In the study group, these symptoms were shown before the child reached 6 years of age. The symptoms were manifested in many situations and they continued on regular basis for more than 6 months, significantly impairing the child’s school and social functioning. Exclusion criteria of the study group were other psychiatric or neurodevelopmental disorders, epilepsy, mental retardation, brain injury, such as head trauma with loss of consciousness, or chronic somatic diseases. All participants in the study were administered the Wechsler Intelligence Scale for Children – Revised (WISC-R, Polish adaptation) [19]. Each child with HKD underwent an individual therapy at an outpatient department. During periodic visits (every month), the following methods were applied: psychoeducation and training of parents, behavioural-cognitive training with a reward system for children and educational procedures addressed to teachers. Medication treatment was used only in aggravation of symptoms, because there are no strict recommendations on the choice of drugs for hyperkinetic disorder. Assuming that the structure and coherence are the most optimal factors in the case of HKD, the parents’ consistency with the course of the treatment was evaluated. Patients were assessed for current HKD status and psychiatric disorder (externalizing and internalizing) at the follow-up assessment.

Statistical analysis

All statistical analyses were performed using the Statistica 10.0 PL (StatSoft), PASW Statistics 17.0 (Predictive Solutions) and Statu 12.1. The relationship between qualitative features was checked by the χ2 test of independence and the Fisher’s exact test. Since many variables were not normally distributed according to the Kołmogorow-Smirnow test with Lillefors’ correction and the Shapiro-Wilk test, the analysis used non-parametric tests: the Kruskal-Wallis test with post-hoc test and the Wilcoxon signed rank test and Spearman’s rank correlation. The values of the variables are presented as mean ± SD or median, first and third quartile. The regression analysis was performed. The univariate and multivariate linear regression models were created. The p-value at the level of 0.05 was considered statistically significant.
The study was approved by the Ethics Committee of the Medical University of Bialystok, in accordance with the principles of the Guidelines for Good Clinical Practice.

RESULTS

Statistical analysis of the distribution of values obtained in ICD-10, where median (middle value) in the examined in preliminary study amounted to 15 scores (at dispersion from 10 to 18) and after 11 years – 8 scores (at dispersion from 5 to 11), indicated significant differences in decreasing in the characteristic symptoms for HKD in childhood (Z = 5.58, p < 0.001) (Figure I).
At the moment of completing the psychiatric outpatient care, in 19.1-year-old patients a high percentage of externalizing disorders (conduct disorders, nicotine use) (37%) along with internalizing disorders (anxiety and depressive symptoms) (35.2%) was found. The comparative analysis of the study groups is presented in Table 1. The duration of breastfeeding of children with HKD (mean = 5.3; SD 6.0 months) in the internalizing group (mean = 5.8; SD 6.8) was significantly longer as compared with the externalizing group (mean = 3.6; SD 5.3 months). Single-parent families (47.4%) were more frequent in patients with internalizing disorders. Parents of the study group with externalizing disorders were less educated (30.0% mothers and 35.0% fathers with elementary education). In this group, 85.0% (p = 0.002) of carers exhibited inconsistency in dealing with the child. In the examined group, the mental disorders were more frequent in the families which did not use recommendations imparted during treatment (70.0% parents), and fathers abused alcohol significantly more frequently (40.9%).
A logistic regression model was constructed to identify the predictors of anxiety (internalizing) and conduct disorders (externalizing) in the examination groups. The single-parent families coexisting with the mothers’ anxiety disorders were a significant predictor for the model of internalizing disorders (Table 2).
Birth complications, chronic conflicts in family and depression of mother have proved to be significant risk factors for externalizing disorders in the study group (Table 3). Of the group of 54 patients with HKD only 28 (51.9%) of children used regular systematic therapy (visits every month) throughout the observation period, whereas in 26 (48.1%) cases the visits were sporadic, once or twice a year, usually because of upbringing or educational problems. Lack of the systematic treatment was a significant risk factor of transition of HKD to externalizing disorders; univariate regression model: R = 0.56; SE = 0.12; p < 0.001.

DISCUSSION

Certain limitation of this study was the small group size. However, the author’s intention was to include children with a very similar phenotype of HKD. Despite increased awareness that attention deficit hyperactivity disorder continues into adulthood, the research of transition symptoms of HKD to other psychopathology in ontogeny is open. The symptoms of HKD, as the studies indicate, do not subside [20, 21], but can be ‘hidden’ in another psychopathology of adulthood. Signs of core domains in the attention deficit and impulsivity are present in varying degree in the psychopathology of adults [15, 22]. In the study group, the percentage of 19-year-old people with externalizing disorders complying with the CD criteria according to ICD-10 was 37%. It should be noted that the internalizing disorders had been in a similar proportion (35.2%) on completion of this research. Many years of observation of the same group of patients showed that HKD is a chronic disease and lack of systematic long-term treatment increases the risk of HKD transition to antisocial phenotypes.
Although HKD is a genetically conditioned neurodevelopmental disorder of inattention and impulse control [23, 24], the environmental factors may play an important part in the behavioural phenotype [25-29]; they may also contribute to further development of psychopathology. Undoubtedly, the environmental factors responsible for gene expression regulation largely contribute to the pathological symptoms but the mechanism of mutual interaction in the long-term is not fully understood. The author found a significant relationship between the single-parent family coexistence of mothers’ anxiety disorders and internalizing disorders of the participants. The combination of events, such as birth complications, mother’s depression and chronic conflict in the family, was significantly related to the occurrence of antisocial symptoms in the study group of children with HKD. Further, in the examined group, the duration of breastfeeding was shorter in patients with externalizing compared with participants with internalizing disorders. While the role of the breastfeeding in the brain development still remains unclear, it is possible that the some cognitive or behavioural dysfunction may be the result of the short duration of breastfeeding [30]. Other longitudinal studies have confirmed that interactions between biological vulnerability and poor parenting are important in predicting further externalising problems [5, 31-33]. Children with HKD may be at risk of becoming a group of emotional deprivation, particularly if parents experience mental disorders [31, 33]. Parents present the relations with their children as stressful and giving no satisfaction. Child’s disorganized activities usually evoke negative reactions of caregivers. Long-lasting lack of positive responses from the family may reinforce the child’s dysfunctional behaviours and problems with social adjustment. Research finds that family functioning may be an important determinant of course of HKD. When behavioural or psychological difficulties appear, parents need to understand this problem, the meaning of specific symptoms and their causes as well as the treatment effects and consequences. The therapeutic interventions comprise also of supporting carers’ skills and teaching them the strategies of taking care of a child, which change as the child development.

CONCLUSIONS

1. Long-term clinical observation showed that the HKD is a chronic disease, and appropriate systematic treatment until adulthood may significantly reduce undesirable behaviours.
2. Completion of the treatment programs should be monitored systematically for many years, which greatly influences the results of school education and increases the chances for correct psychosocial development.
3. Parents’ mental disorders/conflicts considerably reduce the treatment effects, thereby.

Conflict of interest

Absent.

Financial support

Absent.

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