Three hundred and fifty-one participants were screened initially for the trial, which resulted in 144 participants who met inclusion criteria and who were randomised to receive either PCSO-524® or a placebo for 14 weeks. The mean age was 8.7 years (SD = 2.24) of whom 123 were male and 21 were female (see Table 2 for demographic data). In total, the data of 112 participants were included for final analysis through the use of intention-to-treat analysis, with the final observation carried forward. Following random assignment and dropouts, there was a significant demographic difference in the number of females in the PCSO-524® group compared to the placebo group (N = 17; PCSO-524® n = 14). To further explore this, a repeated measure analysis was conducted investigating the effect of treatment on male and females only. This data is reported further on.
Whole sample treatment group differences were noted in secondary outcome, the COMPASS cognitive task, which included significant improvements in working memory on three domains in favour of PCSO-524®. No further treatment group differences were found in an analysis of the entire sample on remaining primary and secondary outcomes.
As the sample population included children taking pharmaceutical medications, careful interpretation of the analysis and outcomes was needed. Each result was analysed using diagnosis and medication status as a covariate. Any statistical influence of these covariates on any outcome is noted in the relevant analysis. These participant numbers are broken down by groups including on-site testing, distant testing and gender as well as to which treatment group these participants were randomised (see Table 3 and Fig. 1).
ADHD assessment scales
Conners Parent Rating Scale
A baseline summary of the CPRS data was included investigating differences between demographic data (see Table 4). Comparisons between gender, medication status, diagnosis status and testing location were conducted using paired sample t test. Any significant outcome was further investigated using Wilcoxon signed-rank test for non-parametric datasets. There were significant baseline differences for the peer relations (p < 0.05), oppositional defiant disorder (p < 0.01), impaired relationships (p < 0.01) and impaired home life (p < 0.01) outcomes between the diagnosed and non-diagnosed groups as well as significant differences on the peer relations (p < 0.05) and impaired relationships (p < 0.05) between medicated and non-medicated groups. No further differences were noted in any other demographic data at baseline. Despite these demographic differences, following randomisation, there were no significant differences between treatment groups on any of the CPRS outcomes.
Analysis of the primary outcome found no significant differences between treatment groups on CPRS following 14-week supplementation. To further understand potential treatment effects, we also conducted post hoc analyses with subgroups. This was done to better understand whether there was a treatment effect related to the severity of the symptoms displayed by children and adolescents. Subsample analysis indicated significant treatment effects for participants who had less-severe symptoms (high inattention, high hyperactivity or no subtype—non-combined type) than those who had more severe symptoms (combined high hyperactivity and inattention—combined type) based on attention-deficit/hyperactivity disorder IV rating scale scores (DuPaul et al. 1998).
Non-combined type (NCT) (N = 43; PCSO-524® n = 23) analysis revealed a significant improvement in children who consumed PCSO-524® on CPRS scores of hyperactivity, learning abilities and improved behaviour at home, as well as improvements on DSM scores of attention and hyperactivity. Furthermore, there was a significant reduction in ADHD probability ratings in children who consumed PSCO-524® compared with placebo; this result was associated with a main effect for diagnosis (p = 0.03) (see Table 5). No baseline differences were seen in the NCT sample. There were also no significant differences between treatment groups in terms of those with high inattention (p = 0.08) or high hyperactivity (p = 0.10) at baseline. The NCT subsample was comprised of three classifications, which included those who met criteria for high inattention, those who met criteria for high hyperactivity and those who did not meet criteria for either high inattention or high hyperactivity, denoted from here as non-subtype group. Further analysis of these groups found that those children taking PCSO-524® and displaying high inattention (N = 19; PCSO-524® n = 11) improved in parental ratings of executive function (p = 0.01; d = 0.38), aggression (p = 0.01; d = 0.70), conduct (p < 0.01; d = 1.03) and oppositional defiance (p = 0.04; d = 0.46). Improvements in aggression and oppositional defiance were associated with main effects for medication (p < 0.05) and diagnosis (p < 0.05). This may indicate the potential for PCSO-524® as an adjunct therapy in ADHD-diagnosed children displaying specific issues with attention; however, future studies are needed to establish this association. Improvements in executive function were also associated with a main effect for diagnosis (p < 0.05). There were no improvements on any domain for those children displaying symptoms of high hyperactivity (N = 10; PCSO-524® n = 4) or the non-subtype group (N = 15, PCSO-524® n = 9). Only a single baseline difference was noted in the conduct issues outcome for the non-subtype group (p < 0.05).
Group analysis of the combined type (CT) (N = 65; PCSO-524® n = 29) revealed an improvement in attention, executive function and DSM ratings of attention in the placebo group (see Table 6); however, both symptoms of executive function and DSM ratings of attention showed a significant main effect for medication status, which highlights the possible influence of pharmaceutical treatment on parental ratings of participant’s behaviour. No baseline differences were noted in the CT sample.
Clinical Global Impression scale
There were no significant differences between treatment groups at baseline or during the following 14 weeks of treatment.
Computerised Mental Performance Assessment System
There were no significant differences between groups at baseline for any of the cognitive measures. Results of the reaction time cognitive data did not include fast guesses (<200 ms). Whole sample analysis (N = 85) revealed significant effects in favour of PCSO-524® between baseline and week 8. ANCOVA analysis was conducted using diagnosed and medication status as well as baseline scores as covariates. The main outcomes were improved memory accuracy scores of participants in the PCSO-524® group when they recalled target (p = 0.05, d = 0.48) and non-target (p = 0.02, d = 0.56) pictures correctly; this is complemented by significant overall picture recognition accuracy (p = 0.02, d = 0.56) (see Fig. 2a–c). There were no main effects for diagnosis or medication on any of the whole sample outcomes.
COMPASS subsample analysis
Baseline differences (p < 0.05) were noted between treatment groups on three subscores for the word recognition task in the diagnosed (Ds) (n = 28; PCSO-524® n = 14) subsample only. A single significant difference was noted on the delayed word recall task in the non-diagnosed (NDs) (n = 57; PCSO-524® n = 31) subsample (p < 0.05). No other baseline differences were noted in either subsample. There were no main effects for medication in the diagnosed subsample on any COMPASS outcome.
In the NDs subsample, significant improvements were seen on the same working memory scores as in the whole sample analysis. ANCOVA analysis of the subsample revealed that those in the PCSO-524® group had improved picture recognition (p = 0.03, d = 0.67), correct target picture recognition (p = 0.05, d = 0.58) and correct non-target picture recognition (p = 0.02, d = 0.69). In the Ds subsample, a significant improvement in numeric working memory (Fig. 3) was demonstrated in those taking PCSO-524® between baseline and week 8 (p = 0.02, d = 0.92).
Test of Variables of Attention
The TOVA is a highly demanding task that requires significant sustained attention during a long period of time. Analysis was conducted using a 2 × 2 repeated measures ANOVA (quarter × time) on each mode (target-infrequent [first half] mode or target-frequent [second half]) mode to evaluate the individual influences of each quarter on the data. Any quarter that had excessive omission errors (>90%) was considered invalid. Participants whose data was deemed invalid were removed from the final analysis. Seventy-seven participant datasets were included in the final analysis. There were no significant differences between groups at baseline. No statistically significant differences were found between the treatment groups in whole sample analysis.
TOVA subsample analysis
In the NDs subsample (n = 52; PCSO-524® n = 28), the PCSO-524® group showed significantly increased speed when they gave a correct response to a target following an error (post-commission) and demonstrated sustained consistency of those responses compared with placebo over the 14 weeks during the target-infrequent mode (see Table 7). In the target-frequent mode, those in the placebo group made significantly more multiple responses than those in the PCSO-524® group (see Table 8). This demonstrated an example of improved inhibitory mechanisms. For the Ds sample (n = 25; PCSO-524® n = 12), those in the PCSO-524® group showed slower reaction times when they responded to target stimuli (p = 0.09, d = 0.18), which was complemented by another trend, which demonstrated that those children who consumed PCSO-524® made fewer errors than the placebo group over 14 weeks (p = 0.08, d = 0.20).
Brunel Mood Scales (BRUMS)
The data of 108 participants were used for analysis. There were no significant differences between treatment groups at baseline. Whole sample analysis revealed significant changes in feelings of fatigue and confusion. Fatigue increased in the PCSO-524® group until week 8 (p = 0.02, d = 0.49), when it levelled off at week 14 (p = 0.01, d = 0.53), whereas there was a consistent decrease in fatigue in those children in the placebo group. Both treatment groups had reduced feelings of confusion during the 14 weeks; however, the placebo group did so more significantly at week 8 (p = 0.02, d = 0.46) and at week 14 (p = 0.01, d = 0.55).
BRUMS subsample analysis
In the Ds subsample, there was a significant decrease in feelings of confusion in the placebo group at week 8 (p = 0.00, d = 1.14) and at week 14 (p = 0.03, d = 0.68). Subsample analysis of the NDs subsample demonstrated a significant reduction in feelings of fatigue in the placebo group between baseline and week 14 (p = 0.02, d = 0.63), compared with PCSO-524®. This was accompanied by a trend in decreased feelings of depression (p = 0.07, d = 0.48) and confusion (p = 0.07, d = 0.47) in both treatment groups, with greater significance in the placebo group.
To evaluate the difference between gender on behavioural outcomes, a repeated measure ANOVA was conducted on males in the study. An analysis on females was not conducted due to the low number of females at the conclusion of the study coupled with the difference in numbers between groups. A repeated measures ANOVA using Bonferroni multiple comparison analysis was conducted on the male-only cohort. There were no significant differences between treatment groups on any CPRS domains following a whole sample analysis (N = 91; PCSO-524® n = 38) or for a CT analysis (N = 56; PCSO-524® n = 21). In an NCT analysis of males only (N = 35; PCSO-524® n = 17), there were significant improvements in CPRS ratings of attention (p = 0.03, d = 0.74), hyperactivity (p = 0.00, d = 1.13), learning problems (p = 0.03, d = 0.78), as well as DSM ratings of attention (p = 0.02, d = 0.80) and hyperactivity (p = 0.00, d = 1.09). There were further improvements on the global index of ADHD (p = 0.01, d = 0.86) and ratings of impaired home life (p = 0.01, d = 0.82), as well as improved ADHD probability ratings (p = 0.00, d = 0.91). The CPRS ratings of attention and the ADHD probability scores were associated with main effects for diagnosis and medication status.
There was a significant difference between groups in ‘feeling colder’ at baseline; however, this difference dissipated at the end of the study. No other differences in symptoms were noted at baseline or during the course of the study (see Table 9).
Week 18 final behaviour (CPRS) and mood (BRUMS) follow-up compliance completion was low (53%). Paired sample t test indicated a significant worsening in executive function for the placebo group in the CT condition (p = 0.05; d = −0.34). There was a significant increase in tension (p = 0.05, d = 0.36) throughout the whole sample in the PCSO-524® group, following cessation of treatment. In subsample analysis, those children who had been diagnosed with ADHD and who had finished taking PCSO-524® showed increased tension (p = 0.05, d = 0.51) and symptoms of depression (p = 0.02, d = 0.58). These results should be interpreted with caution due to the low completion rate.
Dropouts, withdrawals and compliance
There were 24 participant dropouts. The majority of dropouts occurred due to family issues (n = 9 placebo; PCSO-524® n = 4) that left the participant unable to complete testing procedures (see Fig. 1 for a study recruitment flowchart). A common issue with younger participants was an inability to swallow the capsules (placebo n = 7; PCSO-524® n = 4). Some participants began ADHD medication or made adjustments to their medication regimen (placebo n = 3; PCSO-524® n = 2) and were excluded from further testing. Two participants withdrew from the study due to symptoms; one participant complained of an increase in noise sensitivity (placebo), and one parent reported an increase in the child’s hyperactivity while at home (PCSO-524®). Two further participants did not comply with treatment and testing protocols and were withdrawn from the analysis (PCSO-524® n = 2). Ten interstate participants were lost to follow-up and failed to return any data (PCSO-524® n = 5). Compliance rates were determined via a pill count, the compliance diary and a follow-up telephone call. The mean recorded compliance rates with the single daily intake were 96.67%. There were no significant differences between compliance, diagnosis and ADHD medication between the treatment groups.