Table 1.
Summary of MRI brain iron studies in ADHD and RLS. ADHD: attention deficit hyperactivity disorder; MFC: magnetic field correlation; mo: months; PLMS: periodic limb movements of sleep; QSM: quantitative susceptibility mapping; RLS: restless legs syndrome; ROI: regions of interest; SF: serum ferritin, Y: years.
| Author | Study Population | Method | Results | ||
|---|---|---|---|---|---|
| Condition | Participant Number | Age (Y): Range Mean |
|||
| Adisetiyo et al., 2014 [15] | ADHD |
n = 22 ADHD n = 27 controls |
8–18 12.7 13.3 |
MRI imaging relaxation rates (R2, R2*, R2′) and magnetic field correlation (MFC) in the globus pallidus, putamen, caudate nucleus, and thalamus -R2, R2*, R2′ -MFC |
-No difference in R values -Lower MFC in ADHD (lower brain iron) |
| Adisetiyo et al., 2019 [16] | ADHD |
n = 30 ADHD n = 29 controls |
8–18 14.0 13.9 |
-R2* -MFC |
-No difference in R2* or MFC -Increased R2* and MFC (increased brain iron) with psychostimulant use duration in ADHD more than with age |
| Allen et al., 2001 [17] | RLS |
n = 5 RLS n = 5 controls |
66.2 66.4 |
-R2′ | -Lower R2′(lower brain iron) in RLS and in proportion to RLS severity |
| Astrakas et al., 2008 [18] | RLS |
n = 25 RLS n = 12 controls |
55–82 66.5 54–89 65.7 |
-T2 | -Higher T2 (lower brain iron) in RLS |
| Beliveau et al., 2022 [19] | RLS |
n = 72 RLS n = 72 controls |
46–59 51.9 (median) 51.0 (median) |
-R2, R2′, and R2* -QSM |
-Higher R and QSM values (increased iron brain iron) in RLS |
| Cortese et al., 2012 [20] | ADHD |
n = 18 ADHD n = 9 controls n = 9 psychiatric controls |
118.8 mo 120.8 mo 123.5 mo |
-T2* | -Higher T2* (lower brain iron) in ADHD -SF and T2* values did not correlate significantly in most regions |
| Earley et al., 2006 [21] | RLS |
n = 22 early-onset RLS n = 19 late-onset RLS n = 39 controls |
57.1 67.4 60.5 |
-R2′ | -Lower R2′ (lower brain iron) in early-onset RLS symptoms, but not late-onset RLS |
| Godau et al., 2008 [22] | RLS |
n = 6 RLS n = 19 controls |
47–68 60 59 |
-T2 | -Higher T2 (lower brain iron) in RLS |
| Hasaneen et al., 2017 [23] |
ADHD |
n = 17 ADHD n = 18 controls |
6–15 8.4 8.5 |
-R2* | -Lower R2* (lower brain iron) in ADHD which correlated with ADHD type but not with ADHD severity |
| Knake et al., 2010 [24] | RLS |
n = 12 RLS n = 12 controls |
43–46 58.5 41–74 56.8 |
-T2 | -No difference in T2 values |
| Li et al., 2016 [25] | RLS |
n = 39 RLS n = 29 controls |
58.4 57.9 |
-QSM | -Lower magnetic susceptibility (lower brain iron) in RLS and possible connection to PLMS |
| Margariti et al., 2012 [26] | RLS |
n = 11 RLS n = 11 controls |
48–70 55.3 42–73 56.1 |
-T2 | -Lower T2 (higher brain iron) in RLS |
| Moon et al., 2014 [27] | RLS |
n = 37 RLS n = 20 early-onset RLS n = 17 late-onset RLS n = 40 RLS controls n = 20 early-onset controls n = 20 late-onset controls |
50.3 58.1 47.0 59.4 |
-T2 | -Higher T2 (lower brain iron) in late-onset RLS, but not early-onset RLS |
| Moon et al., 2015 [28] | RLS |
n = 37 RLS n = 40 controls |
53.8 53.2 |
-R2, R2*, and R2′ | -Relaxometry and ROI determination methods significantly influenced the outcome of brain iron estimates |
| Rizzo et al., 2013 [29] | RLS |
n = 15 RLS n = 15 controls |
51.0 51.0 |
-Phase from gradient-echo scan | -Higher phase values (lower brain iron) in RLS |