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| Psychiatry Investig > Volume 22(11); 2025 > Article |
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Availability of Data and Material
The datasets generated or analyzed during the study are available from the corresponding author on reasonable request.
Conflicts of Interest
Min-Hyeon Park, a contributing editor of the Psychiatry Investigation, was not involved in the editorial evaluation or decision to publish this article. All remaining authors have declared no conflicts of interest.
Author Contributions
Conceptualization: Myeongju Cho, Bora Kim. Data curation: Myeongju Cho, Eunseol Ko. Formal analysis: Myeongju Cho, Eunseol Ko. Funding acquisition: Min-Hyeon Park. Methodology: Myeongju Cho, Min-Hyeon Park. Supervision: Min-Hyeon Park. Validation: Myeongju Cho, Eunseol Ko. Visualization: Myeongju Cho, Eunseol Ko. Writing—original draft: Myeongju Cho. Writing—review & editing: Eunseol Ko, Haemi Cho, Hyun Jung Kim, Dong-Gyun Han, Bora Kim, Min-Hyeon Park.
Funding Statement
This research received support from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number RS-2023-00266131) and the National Research Foundation of Korea (NRF) grant, funded by the Korea government (Ministry of Science and ICT) (RS-2025-00556589).
Acknowledgments
None
| Author (year) | Country | N | BIF (N) | BIF IQ (range) | IQ assessment tools | Age (range, yr) | Male (%) |
|---|---|---|---|---|---|---|---|
| Wang et al. (2024) [2] | UK | 14,094 | 2,234 | 70-85 | Four cognitive tests (including general ability) | 44-50 | 54.7 |
| Singh et al. (2024) [22] | India | 80 | 40 | 80.5 (3.7)* | Raven’s standard progressive matrices | 18-45 | 50.0 |
| Rudra et al. (2024) [23] | UK | 6,872 | 666 | 70-79 | NART | 57.2 (19.0)* | 44.3 |
| Wexler et al. (2023) [49] | USA | 2,516 | 523 | 70-79 | WISC-IV/-V | 6-13‡ | 69.1 |
| Karande et al. (2023) [46] | India | 100 | 100 | 73-80 | WISC-R or Binet-Kamat Test of Intelligence | 15.0-16.8 | 67.0 |
| Peltopuro et al. (2023) [8] | Finland | 417 | 156 | 70-85 | Various cognitive tests (including Kohs block test) | 41-53 | 57.1 |
| Wagemaker et al. (2022) [42] | Netherlands | 40 | 19 | 71-83 | WISC-V | 12-15 | 52.6 |
| Lim et al. (2022) [3] | UK | 21,796 | 2,786 | 70-85 | NART | 16-74 | 45.9‡ |
| Karande et al. (2022) [38] | India | 100 | 100 | 74-80 | WISC-R or Binet-Kamat Test of Intelligence | 14.0-15.2 | 65.0 |
| Hetland et al. (2021) [24] | Norway | 162 | 29 | 70-85 | WASI | 26.1 (8.4)* | 62.1 |
| Galletta et al. (2020) [56] | Italy | 55 | 25 | 71-84 | WAIS-R | 27.6 (9.3)* | 16.0 |
| Predescu et al. (2020) [34] | Romania | 85 | 16 | 70-85 | N/A | 6-11 | - |
| Melby et al. (2020) [26] | Norway | 176 | 30 | 70-84 | WAIS-III | 19.2 (0.5)* | 33.0 |
| Kashyap et al. (2020) [45] | India | 50 | 25 | 70-85 | MISIC | 10 (3.5)* | 68.0 |
| Blasi et al. (2020) [35] | Italy | 36 | 36 | 70-85 | WISC-III | 6-11 | 50.0 |
| Smirni et al. (2019) [44] | Italy | 116 | 65 | 71-84 | WISC-IV | 12.6-13.4 | 53.8 |
| King et al. (2019) [4] | Australia | 2,950 | 262 | Below 1-2 SD | LOI | 14-15 | - |
| Hassiotis et al. (2019) [40] | UK | 15,453 | 2,108 | 71-85 | Various cognitive tests (including Copying Designs Test) | 26-42 | - |
| Szumski et al. (2018) [19] | Poland | 49 | 49 | 69-85 | WISC | 11-36 | 69.4 |
| Ozkan et al. (2018) [43] | Turkey | 60 | 30 | 70-85 | WISC-R | 8.6 (1.0)* | 73.0 |
| Barnevik Olsson et al. (2017) [50] | Sweden | 50 | 50 | 70-84 | WPPSI-III | 9-13 | 91.8 |
| Nouwens et al. (2017) [57] | Netherlands | 250 | 141 | 70-85 | WPPSI-III, WISC-III, WAIS-III | 3-70†‡ | 60.8‡ |
| Hassiotis et al. (2017) [28] | UK | 15,983 | 1,701 | 70-85 | NART | 16-74 | - |
| Wieland and Zitman (2016) [32] | Netherlands | 4,265 | 96 | 70-84 | WAIS-III | 16-88‡ | 24.0 |
| Panicker and Chelliah (2016) [25] | India | 82 | 41 | 75-79 | Binet Kamat Test of Intelligence | 7-17 | 78.0 |
| Fallea et al. (2016) [47] | Italy | 700 | 270 | 71-84 | - | 6-47‡ | 59.0‡ |
| Baglio et al. (2016) [51] | Italy | 59 | 28 | 70-85 | WISC-III | 9.5 (1.3)* | 57.1 |
| Wieland et al. (2015) [55] | Netherlands | 1,261 | 235 | 70-84 | WAIS-III | 33.4 (12.5)* | 33.0 |
| Wieland et al. (2014) [27] | Netherlands | 1,261 | 235 | 70-84 | WAIS-III | 33.4 (12.5)* | 33.0 |
| Stinson and Robbins (2014) [30] | USA | 235 | 55 | 70-85 | Various cognitive tests (including WAIS-III) | 18-63 | 86.0‡ |
| Gigi et al. (2014) [29] | Israel | 499,766 | 76,962 | 71-84 | Cognitive test battery | 16-17 | 100 |
| Fenning et al. (2014) [54] | USA | 172 | 24 | 77.8 (4.0)* | Stanford Binet Intelligence Scale-IV | 5-6 | 58.0‡ |
| Christensen et al. (2013) [48] | USA | 184 | 20 | 71-84 | Stanford Binet Intelligence Scale-IV | 5-9 | 75.0 |
| Hassiotis et al. (2011) [33] | UK | 6,872 | 1,053 | 70-85 | NART | 42.3 (0.7)* | 54.8 |
| Emerson et al. (2010) [39] | Australia | 3,370 | 408 | 70-84 | Peabody Picture Vocabulary Test | 6-7 | - |
| Karande et al. (2008) [12] | India | 100 | 55 | 71-84 | WISC-R | 8-17 | 63.6 |
| Hassiotis et al. (2008) [13] | UK | 8,450 | 1,040 | 70-84 | NART | 16-74 | 51.7 |
| Van der Meere et al. (2008) [11] | Netherlands | 40 | 40 | 71-75 | WISC-R | 10-12 | 100 |
| Rimmerman et al. (2007) [20] | Israel | 127 | 127 | 70-79 | - | 28.4 (4.8)* | 48.0 |
| Fenning et al. (2007) [52] | USA | 217 | 29 | 71-84 | Stanford Binet Intelligence Scale-IV | 5-6 | 65.5 |
| Crocker et al. (2007) [31] | Canada | 281 | 84 | 71-85 | EIHM | 31.1 (8.5)* | 100 |
| Chen et al. (2006) [41] | USA | 1,611 | 178 | 70-80 | Stanford Binet Intelligence Scale-III | 27-33 | 50.6 |
| Rimmerman et al. (2005) [21] | Israel | 127 | 127 | 69-85 | - | 28.4 (4.8)* | 48.0 |
| Finn (1992) [53] | USA | 8,336 | 1,084 | 70-84 | Revised Beta | 25.0† | 100 |
| Thompson et al. (1990) [36] | USA | 79 | 14 | 70-84 | WISC-R | 6-17 | 48.0 |
‡ sample characteristics (age and male % values) are based on BIF sample unless specific BIF data were not available, in which case total sample characteristics are reported.
-, data were not reported; BIF, borderline intellectual functioning; NART, National Adult Reading Test; WISC-R, Wechsler Intelligence Scale for Children; WASI, Wechsler Abbreviated Scale of Intelligence-Revised; WAIS, Wechsler Adult Intelligence Scale; MISIC, Malin’s Intelligence Scale for Indian Children; SD, standard deviation; LOI, Learning Outcome Index; WPPSI, Wechsler Preschool and Primary Scale of Intelligence; EIHM, E´preuve Individuelle d’Habilete´ Mentale (individual test of mental ability).
| Author (year) | Study design | Q1 | Q2 | Q3 | Q4 | Q5 | MMAT score |
|---|---|---|---|---|---|---|---|
| Wang et al. (2024) [2] | Quantitative non-randomized | Y | Y | C | Y | Y | 4 |
| Singh et al. (2024) [22] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Rudra et al. (2024) [23] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Wexler et al. (2023) [49] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Karande et al. (2023) [46] | Quantitative descriptive | N | Y | Y | Y | Y | 4 |
| Peltopuro et al. (2023) [8] | Quantitative non-randomized | Y | Y | N | Y | Y | 4 |
| Wagemaker et al. (2022) [42] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Lim et al. (2022) [3] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Karande et al. (2022) [38] | Quantitative descriptive | N | Y | Y | Y | Y | 4 |
| Hetland et al. (2021) [24] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Galletta et al. (2020) [56] | Quantitative non-randomized | Y | Y | Y | Y | Y | 4 |
| Predescu et al. (2020) [34] | Quantitative non-randomized | Y | Y | C | Y | Y | 4 |
| Melby et al. (2020) [26] | Quantitative non-randomized | Y | Y | C | Y | Y | 4 |
| Kashyap et al. (2020) [45] | Quantitative RCT | Y | Y | Y | N | Y | 4 |
| Blasi et al. (2020) [35] | Quantitative non-randomized | Y | Y | Y | N | Y | 4 |
| Smirni et al. (2019) [44] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| King et al. (2019) [4] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Hassiotis et al. (2019) [40] | Quantitative non-randomized | Y | C | N | Y | Y | 3 |
| Szumski et al. (2018) [19] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Ozkan et al. (2018) [43] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Barnevik Olsson et al. (2017) [50] | Quantitative non-randomized | Y | Y | N | Y | Y | 4 |
| Nouwens et al. (2017) [57] | Quantitative non-randomized | Y | Y | C | Y | Y | 5 |
| Hassiotis et al. (2017) [28] | Quantitative non-randomized | Y | C | Y | Y | Y | 4 |
| Wieland and Zitman (2016) [32] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Panicker and Chelliah (2016) [25] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Fallea et al. (2016) [47] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Baglio et al. (2016) [51] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Wieland et al. (2015) [55] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Wieland et al. (2014) [27] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Stinson and Robbins (2014) [30] | Quantitative non-randomized | N | Y | Y | Y | Y | 4 |
| Gigi et al. (2014) [29] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Fenning et al. (2014) [54] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Christensen et al. (2013) [48] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Hassiotis et al. (2011) [33] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Emerson et al. (2010) [39] | Quantitative descriptive | Y | Y | Y | Y | Y | 5 |
| Karande et al. (2008) [12] | Quantitative non-randomized | N | N | Y | N | Y | 2 |
| Hassiotis et al. (2008) [13] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Van der Meere et al. (2008) [11] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Rimmerman et al. (2007) [20] | Quantitative non-randomized | Y | N | Y | Y | Y | 4 |
| Fenning et al. (2007) [52] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Crocker et al. (2007) [31] | Quantitative non-randomized | Y | Y | Y | C | Y | 4 |
| Chen et al. (2006) [41] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Rimmerman et al. (2005) [21] | Quantitative non-randomized | Y | N | Y | Y | Y | 4 |
| Finn (1992) [53] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |
| Thompson et al. (1990) [36] | Quantitative non-randomized | Y | Y | Y | Y | Y | 5 |

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