To explore the characteristics of childhood trauma experiences, implicit memory, and explicit memory in first-degree relatives (parents) of children with comorbid attention deficit hyperactivity disorder (ADHD), in order to provide insight into the disorder's neuropsychological pathogenesis and inform family-based psychological interventions.

A total of 88 children with ADHD (disease group) who attended the outpatient department of Fouth People’s Hospital of Hefei from July 2022 to February 2024, along with their first-degree relatives, were selected, of which 31 were classified as the comorbidity subgroup. Additionally, 30 healthy children (matched in age, gender, and intelligence) from a primary and secondary school in Hefei, together with their first-degree relatives, were chosen as a healthy control group. The Chinese version of the Swanson Nolan and Pelham Version IV Scale (SNAP-IV) was used to assess the severity of ADHD symptoms in children. The Childhood Trauma Questionnaire-Short Form (CTQ-SF) was employed to evaluate the childhood trauma experiences of the relatives. The lexical perceptual speed test task and lexical recognition task were respectively adopted to measure the implicit memory and explicit memory of the relatives. Analysis of variance (ANOVA) and Pearson correlation analysis were applied for data analyses.

The comorbidity rate of ADHD in the disease group was 27.23% (31/88). The SNAP-IV score of children in the comorbidity subgroup (49.00±12.02) was significantly higher than that in the non-comorbidity subgroup (41.61±10.06) and the healthy control group (13.43±6.89). The total CTQ-SF score of parents in the comorbidity subgroup (45.81±7.96) was higher than that of the non-comorbidity subgroup (40.28±7.78) and the healthy control group (37.03±5.34). Specifically, the scores of emotional abuse and sexual abuse factors in parents of the comorbidity subgroup were higher than those of the other two groups; the score of physical neglect factor was higher than that of the non-comorbidity subgroup; and the scores of emotional neglect and physical abuse dimensions were higher than those of the healthy control group (all P＜0.05). The explicit reaction time in parents of the comorbidity subgroup [(1059.63±122.01) ms] was longer than that of the non-comorbidity subgroup [(928.43±118.17)] ms and the healthy control group [(928.37±202.88) ms], while the accuracy of implicit memory [(20.75±15.16)%] was lower than that of the non-comorbidity subgroup [(58.10±33.18)%] and the healthy control group [(83.61±20.53)%] (all P＜0.001). The accuracy of implicit memory in parents of the comorbidity subgroup was negatively correlated with the total CTQ-SF score (r=-0.506), sexual abuse score (r=-0.422), and physical neglect score (r=-0.479), whereas there was no significant correlation between explicit memory and childhood trauma (P＞0.05).

First-degree relatives of children with comormid ADHD have more severe childhood trauma experiences and deficits in implicit and explicit memory functions. Furthermore, the childhood trauma experiences of relatives are closely associated with implicit memory impairment. This suggests that the early-life trauma of parents may indirectly increase the risk of comorbidities in children with ADHD by affecting memory function, which can provide a target for family psychological intervention for ADHD.