Table 1 The basic characteristics of included studies

Memantine

 Biederman et al. (2017) [46]

USA

26

Adults, 15–57 (35.33)

• DSM-IV criteria

• AISRS score ≥ 20

• Clinically significant chronic medical conditions

• IQ < 80

• Any unstable psychiatric condition

• Drug or alcohol abuse

• Pregnant or nursing females

 Findling et al. (2007) [32]

USA

16

Children, 6–12 (8.1)

• DSM-IV criteria

• K-SADS-PL

• Any unstable psychiatric condition, except for oppositional defiant disorder

• A general medical condition that might interfere with the conduct of the study

 Riahi et al. (2020) [47]

Iran

39

Children 6–12 (9.51)

• DSM-IV criteria

• Conner’s score ≥ 20

• A serious psychiatric disorder

• History of lack of response to memantine

• History of severe side effects associated with memantine and methylphenidate

 Mohammadi et al. (2015) [36]

Iran

40

Children, 6–11 (8.6)

• DSM-IV criteria

• K-SADS-PL

• Other psychiatric disorders

• Mental retardation (IQ < 70)

• Clinically significant chronic medical condition

• Current abuse or dependence on drugs in the last 6 months

 Mohammadzadeh et al. (2019) [48]

Iran

40

Adults, 18–45 (33.1)

• Parents of ADHD children

• DSM‐IV

• WURS

• Mental disability

• The presence of any other psychiatric disorder

• Substance or alcohol abuse (in a recent month)

• Pregnant women

• History of allergy to memantine

• The presence of a serious medical illness

 Surman et al. (2013) [35]

USA

34

Adults, 18–60 (41.8)

• DSM-IV

• AISRS inattentive score ≥ 14

• CGI-S ≥ 4

• Any history of renal impairment, hepatic impairment, an organic brain disorder, a seizure disorder

• IQ < 75

• Clinically unstable psychiatric conditions

• History of substance dependence or abuse

• Pregnant or nursing females

Donepezil

 Cubo et al. (2008) [37]

Spain

20

Children and adolescents, 7–17 (11.3)

• DSM-IV criteria

• Evidence of a secondary tic disorder

• Mental retardation or autism

• Diseases that would be expected to alter the safety profile of donepezil

• All females of reproductive age were required to provide a negative urine pregnancy test

 Doyle et al. (2006) [22]

NA (case series)

8

Adolescents, 10–17 (13.5)

• DSM-IV criteria

–

 Wilens et al. (2000) [39]

NA (case series)

5

Children and adolescents, 8–17 (13.6)

• DSM-IV criteria

–

 Wilens et al. (2005) [38]

USA

13

Children and adults (26)

• DSM-IV criteria

• Exclusionary comorbid conditions

Galantamine

 Biederman et al. (2006) [40]

USA

28

Adults, 18–55 (35.9)

• DSM-IV criteria

• Clinically significant chronic medical conditions

• IQ lower than 80

• Clinically unstable psychiatric conditions

• Drug or alcohol abuse or dependence within the 6 months preceding the study

• Pregnant or breast-feeding women