Table 1. Characteristics of included systematic reviews.

Reference	Population criteria & age	Intervention	Comparison	Outcome	Quality of the Evidence (grade)
Wang et al. 11	40 male participants.Range of age: 18–30 years.Mean age of participants: 20.2 years intervention, 21.5 years control.	L-Carnitine.	Placebo	No significant improvement in relevant indicators for DS patients.	Overall Neurological Efficacy: Low (due to inconsistency and imprecision).
Livingstone et al. 12	Down’s Syndrome (DS) participants aged 18 and above. 427 participants.	Memantine, Simvastatin, Donepezil, Antioxidant, Acetyl-L-carnitine.	Placebo	Overall insufficient evidence to confirm effectiveness.	Cognitive Efficacy: Low (due to inconsistency and imprecision).
Oliveira e Faria 14	Adults with DS with signs of dementia. 626 participants.	Antioxidant, acetylcholinesterase inhibitor (donepezil), NMDA receptor antagonists (memantine), fast-acting intranasal insulin.	Placebo.	The use of pharmacological therapies did not demonstrate relevant effects in the treatment of dementia.	Cognitive Efficacy: Low (due to inconsistency and imprecision).
Corniello et al. 15	46 patients with DS, men and women.Progressive cognitive decline, Diagnosis of Alzheimer’s disease (AD) in all cases.	Levetiracetam (LEV) monotherapy, valproic acid (VPA) monotherapy and other anticonvulsants polytherapy.	No placebo group/usual care defined.	LEV and VPA showed great efficacy in seizure control. Treatment with LEV may enhance memory deficits, leading to amelioration of cognitive performances.	Evidence Certainty: Low (due to risk of bias, inconsistency and imprecision)
Islam et al. 13	Down’s Syndrome (DS) participants aged 15 and above. 168 participants.	Memantine	Placebo	No significant effect on the outcomes of cognitive function.	Cognitive Efficacy: Low (due to risk of bias and imprecision)