Table 2.

Summary of study characteristics.

Study ID, ref.	Study design	Sample size	Age (years)	Main findings	Limitations
Jackson-Cowan et al. [24]	Population-based cross-sectional study	N = 109 483	2–17	Childhood AD was significantly associated with developmental delay (aOR: 1.54; 95% CI: 1.40–1.40) (p < 0.001) and ADD/ADHD (aOR: 1.31; 95% CI: 1.20–1.42) (p < 0.001)	Did not control for sedating medications that may have influenced cognitive function (e.g. antihistamines)
Kandelaki et al. [25]	Cross-sectional study	N = 639	5–6	36% of children with language delays and problems in internalisation and externalisation reported comorbid AD	Cross-sectional design prevented the inclusion of follow-up data
Silverberg et al. [26]	Prospective study	Baseline: N = 366 Follow-up: N = 245	18–88	Baseline: 66.8% self-reported ≥1 symptom of cognitive dysfunction (e.g. slowed thinking, difficulty concentrating) Follow-up: 5.4% showed moderate and 5.2% showed severe PROMIS cognitive function T-scores	The baseline cognitive function questionnaire was self-administered and may be subject to recall bias
Vittrup et al. [23]	Population-based longitudinal study	157 113	0–18	Childhood AD was significantly associated with ADHD HR: 1.89 (95% CI: 1.56–2.29)	AD severity was classified based on the proxy of medication use, allowing for misclassification bias