Table 1 Summary of the characteristics of studies included in the meta-analysis.

From: Effect of N-methyl-d-aspartate receptor enhancing agents on cognition in dementia: an exploratory systematic review and meta-analysis of randomized controlled trials

Study (first author, year)

N

Gender

(%male)

Mean age

(years)

Duration

Add-on therapy

Diagnosis

Primary cognition outcome measures

Other cognitive measures

Mean cognitive score at baseline

Study design

Double-blind

Howard et al. (2020)

544

55.7

74.3(8.2)

24 m

Minocycline

Alzheimer disease

MMSE

NR

MMSE:26.4 ± 1.9

RCT

Yes

Bernard et al. (2019)

520

30.3

71.1(7.3)

24w

S47445

Alzheimer disease

ADAS-cog

MMSE

ADAS-cog: 23.6 ± 9.0

MMSE:19.7 ± 2.8

RCT

Yes

Lin et al. (2019)

97

45.1

75.5(7.8)

6w

Benzoate

Dementia

ADAS-cog

CDR, MMSE

ADAS-cog:29.3 ± 12.6

RCT

Yes

Kouzuki et al. (2019)

159

12.6

87.1(0.7)

12w

Monosodium L-glutamate

Dementia

TDAS

GBSS

TDAS:55.2 ± 3.6

GBSS:64.7 ± 3.9

RCT

No

Lin et al. (2014)

60

38.3

70.2(8.5)

24w

Benzoate

Alzheimer disease

ADAS-cog

CIBIC-plus, cognitive composite

ADAS-cog:15.3 ± 7.5

RCT

Yes

Tsai et al. (2014)

30

63.3

76.8(6.0)

8w

Sarcosine

Parkinson’s disease with dementia

CASI

CASI, MMSE, CDR

CASI:57.4 ± 23.9

MMSE:17.3 ± 6.7

CDR:2.2 ± 1.2

RCT

Yes

Chappell et al. (2007)

181

47.5

74.5(9.0)

11w

LY451395

Alzheimer disease

ADAS-cog

CIBIC, Trail Making Part A, Stylus Tapping Test (STT), Single

Digit Modality Test (SDMT)

ADAS-cog:19.4 ± 9.0 MMSE:20.3 ± 3.3

RCT

Yes

Adair et al. (2001)

43

NR

NR

6 m

NAC

Alzheimer disease

MMSE

Four separate batteriesa

MMSE:19.0 ± 3.7

RCT

Yes

Tsai et al. (1999)

17

64.7

72.2(7.3)

4w

D-Cycloserine

Alzheimer disease

ADAS-cog

NR

ADAS-cog:23.5 ± 9.0

MMSE:18.8 ± 5.3

RCT, crossover

Yes

Tsai et al. (1998)

10

40.0

74.7(8.5)

4w

D-Cycloserine

Alzheimer disease

ADAS-cog

MMSE

ADAS-cog:25.5 ± 2.7

MMSE:20.0 ± 5.2

RCT, crossover

Yes

Schwartz et al. (1996)

108

53.8

74.4(8.6)

10w

D-Cycloserine

Alzheimer disease

NR

MMSE, DRS, Implicit memory performance of words

NR

RCT

Yes

Mohr et al. (1995)

40

NR

NR

24w

Cycloserine

Alzheimer disease

Cognitive Drug Research Computerized Assessment System (CDR System)

Mattis Dementia Rating Scale (MDRS), CIBIC, Brief Cognitive Rating Scale (BCRS)

NR

RCT

Yes

Fakouhi et al. (1995)

403

46.1

73.6(8.0)

26w

Cycloserine

Alzheimer disease

Cognitive Drug Research (CDR) computerized test , DRS

MMSE

NR

RCT

Yes

Randolph et al. (1994)

12

70.0

65.0(8.4)

2w

D-Cycloserine

Alzheimer disease

ADAS-cog, RBAD

MMSE

MMSE:21.0 ± 3.3

RCT, crossover

Yes

  1. ADAS-cog Alzheimer’s Disease Assessment Scale-cognitive subscale; CASI Cognitive Abilities Screening Instrument; CDR Clinical Dementia Rating; CIBIC-plus Clinician’s Interview-Based Impression of Change plus Caregiver Input; DRS Dementia Rating Scale; GBSS Gottfries–Bråne–Steen Scale; HVLT Hopkins Verbal Learning Task; MMSE Mini-Mental Status Examination; NR no reported; RBAD Repeatable Battery for the Assessment of Dementia; TDAS the Touch Panel-type Dementia Assessment Scale; WMS, Wechsler Memory Scale.
  2. aBoston Naming Test, Gesture to Command, WMS Figure Reproduction(immediate), HVLT Recall (immediate), HVLT Recognition, Letter fluency, Category fluency, Judgment of Line Orientation.