John Libbey Eurotext

Magnesium Research

Improvement of neurobehavioral disorders in children supplemented with magnesium-vitamin B6 Volume 19, numéro 1, March 2006

Auteur(s) : M Mousain-Bosc1, M Roche2, A Polge2, D Pradal-Prat1, J Rapin3, JP Bali4

1Explorations Fonctionnelles du Système Nerveux, Centre Hospitalier Universitaire Carémeau, Nîmes
2Laboratoire de Biochimie, Centre Hospitalier Universitaire Carémeau, Nîmes
3Département de Pharmacologie, Université de Bourgogne, Dijon
4Laboratoire de Biochimie, Faculté de Pharmacie, Montpellier (France)

Attention deficit/hyperactivity disorder (ADHD) is the most common neurobehavioral disorder presenting for treatment in youth. Children with ADHD are “a group at risk” as far as their further emotional and social development and educational possibilities are concerned [1]. An effective intervention for many hyperactive children, beside methylphenidate and other psychostimulant drugs, is the use of vitamin B6 (pyridoxine) and magnesium (Mg2+). For over 30 years, parents have given high doses of pyridoxine and Mg2+ to their children and have observed decreased physical aggression and improved social responsiveness. However, until now very few studies reported a possible association between magnesium supplementation, ADHD (attention deficit hyperactivity disorders) symptoms, and Mg2+ status of the children: the first one from Liebscher et al. [2] suggested that patients with ADHD should be considered as potentially Mg-deficient as regard to a wrong interpretation of the serum Mg test (tetanic patients have lower Mg values than normals). Other studies from Kozielec et al. reported for the first time an intra-erythrocyte magnesium deficiency in ADHD children [3, 4]. We recently published similar data [5]. However, it is not a true “Mg deficiency” with clinically associated respiratory repletion, as that observed in familial hypomagnesaemia with secondary hypocalcemia [6]. More precisely, it may be called “intracellular Mg deficiency”, affecting mainly neural transmission, very sensitive to such ionic variations.In order to study the relationships between hyperactivity symptoms and Erc-Mg levels, we designed an open study on 40 children with ADHD syndrome. For ethical reasons, performing a double-blind study against either psychostimulants (methylphenidate) or placebo was excluded: parents would be opposed. In addition, psychostimulants have been found to alter magnesium homeostasis [7]. Our results showed a statistically significant improvement of the symptoms after Mg-B6 supplementation, together with a rise in Erc-Mg values.

Patients and methods

Seventy-six children were followed over a period of at least 6 months: 40 children (mean age: 6.49 years; 13 girls and 27 boys) presented clinical symptoms of ADHD (as described in the DSM-IV diagnostic criteria manual [8], after discussion with parents and teachers, and after psychiatric/neurologic examinations) (ADHD group). The control group contained 36 children (mean age: 4.37 years, 14 girls and 22 boys) somatically and behaviourly healthy; these children did not received any Mg-B6 therapy. They were selected for their normal behavior at school.

Each clinical symptoms of ADHD (the tripod hyperexcitability, hyperemotivity/aggressiveness, lack of school attention) was scored between 0 to 4: for hyperactivity, score 0: absence of symptom; score 4: child hyperactive; for attention in school, score 0: child very attentive at school, score 4: child poorly attentive; for hyperemotivity/aggressiveness, score 0: absence of aggressiveness, score 4: child very aggressive and hyperemotive. A Mg-B6 regimen (6 mg/kg/d for magnesium and 0.6 mg/kg/d for vit. B6) was established for at least six months in all ADHD children. No other medical treatment was given before and during the Mg-B6 period.

Serum Mg2+ (S-Mg) and intra-erythrocyte Mg2+ were measured by a colorimetric assay (chlorophosphonazo III) [9] (Erc-Mg) in an INTEGRA automate (Roche Diagnostics) and blood ionized Ca2+ concentrations by electrometric assay (i-Ca) (Bayer Diagnostics). To perform Erc-Mg measurements, red blood cells (RBC) were washed 3 times in 0.9% NaCl, centrifuged, and RBC (1 mL pellet) were lysed in 2 mL water for 15 min at + 4 °C. Then, 1 mL 20% trichloracetic acid was added, the mix was stirred on vortex and centrifuged. The supernatant (1/4 dilution) was used to measure Erc-Mg. When repeated four times in healthy children at one month periods, Erc-Mg values varied by 12% around the initial value. This method was adapted on an INTEGRA automate after calibration with the atomic absorption assay. Biological parameters, including s-Mg, Erc-Mg, and i-Ca, were measured at the first clinical visit of the child; then again, after two months treatment. The following evaluations depended on the frequency of the visits (every six months, for instance). Of course, the control group, only containing healthy children, was not treated with Mg-B6.

Statistics

All statistical analyses were done after testing all variables of interest to determine whether they were approximately normally distributed: two different types of tests for normality were used; Shapiro-Wilk and Shapiro-Francia. Since the majority of the variables are not normally distributed, the non-parametric paired Wilcoxon signed-rank test was used to compare values between before and after treatment. To compare Erc-Mg values between ADHD and control children the non-parametric Mann & Whitney test was used. Significance at p < 0.05.

Results

Table 1( Table 1 ) reports mean values for biological data of ADHD children before and after Mg-B6 supplementation. All statistical comparisons are reported in table 2( Table 2 ).

Erc-Mg values are lower in the ADHD group as compared to the control group

While s-Mg did not statistically differ between ADHD and control groups (data not shown), Erc-Mg values were lower in ADHD as compared to those found in control children (2.05 ± 0.3 mmol/L, n = 41 versus 2.73 ± 0.23 mmol/L, n = 36; p < 0.01) (( figure 1 ) and table 2). In contrast, i-Ca decreased slightly but not significantly (1.22 ± 0.06 mmol/L versus 1.25 ± 0.05 mmol/L for controls; p = 0.2966) (table 2A). However, a statistically significant positive correlation was found between Erc-Mg and i-Ca values in both controls and ADHD children (p = 0.032).

Erc-Mg values increased under Mg-B6 supplementation

When patients received a Mg-B6 supplementation for at least two months, a significant rise in Erc-Mg values was observed in ADHD (2.32 ± 0.41 mmol/L versus 2.05 ± 0.3 mmol/L, p = 0.004), but these values were still lower than for controls (( figure 1 )). ( figure 2 ) reports changes in Erc-Mg values during Mg-B6 therapy in three cases of ADHD: the rate of increase in Erc-Mg values was about 2 months. When Mg-B6 supply was stopped, Erc-Mg values returned to low levels in about 2 months. Administration or suppression of oral Mg-B6 therapy caused respectively a rise and a decrease in Erc-Mg values. In addition, in patients where i-Ca levels were lower than for controls (n = 10), the Mg-B6 supplementation induced a significant rise in both i-Ca and Erc-Mg values (p = 0.0113 and p = 0.0107, respectively) (table 2B).
Table 1 Biological parameters of the study. Mean, SD, median, and range of each parameter (Erc-Mg and i-Ca in mmol/L) measured in control and in ADHD children before and after Mg-B6 treatment are reported.

Number of values

  • Mean
  • (mmol/L)


SD

  • Median
  • (mmol/L)


Range

Erc-Mg

Controls

36

2.76

0.26

2.71

1.01

Before

40

2.05

0.29

2.09

1.23

After

17

2.35

0.37

2.31

1.46

Ca2+

Controls

36

1.25

0.05

1.24

0.22

Before

38

1.22

0.06

1.21

0.25

After

18

1.21

0.11

1.22

0.25


Table 2 Statistical comparison Erc-Mg and i-Ca values in the different groups. Erc-Mg values were obtained after lysis of red blood cells and colorimetric assay as described in Patients and Methods section. I-Ca values came from specific electrode measurements. In (A), statistical comparison was done using unpaired Mann & Whitney non-parametric test. In (B), comparison was done by a paired Student’s t-test after one factor variance analysis. Statistical significance at p < 0.05A) Statistical analysis of Erc-Mg and i-Ca in controls children and in ADHD children before treatment.B) Influence of Mg-B6 therapy on Erc-Mg and i-Ca values in children who exhibited i-Ca values lower than controls.

A

Controls

Before treatment

Mann & Whitney test

i-Ca2+

  • 1.25 ± 0.05
  • (n = 36)


  • 1.22 ± 0.06
  • (n = 38)


U = 528, P > U = 0.667, NS

Erc-Mg

  • 2.76 ± 0.26
  • (n = 36)


  • 2.05 ± 0.29
  • (n = 40)


U = 9, P > U = 0.008

B

  • Before treatment
  • (n = 11)


  • After treatment
  • (n = 11)


  • Variance analysis +
  • paired t-test


i- Ca2+

1.16 ± 0.05

1.24 ± 0.07

  • F = 6.97 p = 0.0157
  • t = 3.09 p = 0.0113


Erc-Mg

1.90 ± 0.36

2.33 ± 0.43

  • F = 6.46 p = 0.0194
  • t = 3.12 p = 0.0107


Evolution of clinical symptoms under supplementation

In almost all cases of ADHD, the Mg-B6 treatment for at least 2 months significantly modified the clinical symptoms of the disease: namely, hyperactivity and hyperemotivity/aggressiveness were reduced and school attention was improved (( figure 3 )). A statistical analysis of the data (chi-2 test) showed that populations of scored values were significantly different (p < 0.0001) before and after Mg-B6 treatment (chi-2 values for hyperactivity, school attention, and hyperemotivity/ aggressiveness: 47.1, 17.2, 17.9, respectively; Wilcoxon signed rank test also evidenced a significant difference for the three groups). When the magnesium treatment was stopped, clinical symptoms of the disease reappeared in few weeks.

Erc-Mg values/clinical symptoms relationships

A majority of children improved under treatment together with a rise in Erc-Mg values (11/19), while only 8/19 did not improve or improved with a decrease in Erc-Mg values. Unfortunately, when we tried to correlate changes in Erc-Mg values (ratio Erc-Mg after treatment versus Erc-Mg before treatment) to changes in clinical symptoms (difference of scored values between after treatment and before treatment), no statistically significant correlation appeared. However, the improvement of hyperactivity appeared to be positively associated to high Erc-Mg values measured before treatment (( figure 4 )). So, the more Erc-Mg values are elevated before treatment (although lower than controls), the more hyperactivity was improved (p = 0.08). This observation could be interpreted by the fact that, when tissues are depleted in Mg, the time (or the dosage) required to restore normal values became more important. Since measurements were done at the same time, these parameters (duration and dosage) have not been taken into account in this study.

Discussion

Magnesium is essential for a number of physiological and biochemical central and peripheral processes. In the brain, traumatic injury causes a decline in magnesium concentrations, focally as well as in blood circulation, and contributes to the development of neurologic deficit [10]. Brain ischemia causes a decline in intracellular free Mg concentrations and magnesium salt administration could improve motor outcome [11]. One of the most important modes of action of magnesium is to inhibit the glutamate N-methyl-aspartate channel, associated to an influx of calcium and, in turn, an excitotoxic cell death and apoptosis [10]. So, while Mg2+ has been shown to be a non-specific inhibitor of calcium channels, it could act as NMDA channel inhibitor [12]. In the same way, Mg2+ could influence catecholamine signaling in the brain [13].

In our study, a slight but significant intra-erythrocyte Mg2+ depletion was evidenced in ADHD patients together with a concomittant decrease in i-Ca concentrations. As we know, Mg2+ is essential for normal central activity and Erc-Mg could be representative of intracellular Mg concentrations: a decrease in Erc-Mg without changes in s-Mg concentrations could be interpreted as an alteration of a magnesium transporter (Na+/Mg2+ exchanger) in erythrocytes with concomitant incidence on neuronal Mg concentrations. The impairment to achieving normal Erc-Mg values under Mg-B6 treatment supports this hypothesis. In addition, Mg pidolate supplementation was found to decrease Na+/Mg2+ exchanger activity with a concomitant rise in Mg2+ and K+ content of erythrocytes in sickle cell disease [14].

Erc-Mg has been described as a controversial biological parameter for the monitoring of Mg2+ deficiency: in contrast to Borella et al. [15] who consider Erc-Mg as a suitable index, Basso et al. [16] present Erc-Mg as not useful in the monitoring of individual changes: we think that, in this last study, a 3-week treatment with Mg2+ without B6 was too short to induce a durable increase in Erc-Mg (vitamin B6 was described to enhance Mg2+ entry through the cell). Anyway, in our study, Erc-Mg measurements were standardized and they appear as a potent indicator of cellular magnesium deficiency.

Ca2+ and Mg2+ cellular contents classically followed the same pathway: when Mg2+ increased, Ca2+ also increased. This can explain the significant correlation between Erc-Mg and i-Ca values as well as the fact that in children who have low i-Ca values, Mg therapy increased i-Ca levels. It can be hypothesized that a genetic factor, which modulates Na+/Mg2+ exchanger activity, may be important in the regulation of Mg metabolism [17].

We also found that increased hyperactivity and decreased school attention were associated to decreased Erc-Mg values: this observation was supported by the fact that Mg-B6 supplementation induced a rise in Erc-Mg values and a concomitant improvement of the clinical symptoms. What are the respective roles of pyridoxine and Mg2+ in these observations? Mg2+ is classically associated to pyridoxine to decrease the irritable side-effects of the B6 therapy. We show here evidence of the role of Mg2+ itself in this therapy. Previous data support this observation: in ADHD disorders, in which disruptive behaviour with hyperactivity was found, psychostimulants are used to improve mental health, probably through increasing synaptic noradrenaline activity. In children who received methylphenidate, Schmidt et al [7] found a significant increase (6%) in plasma Mg2+ concentrations depending on the dosage of the drug, showing a relationship between improvement of hyperactivity and Mg2+ metabolism. More recently, in autistic children with behavioural disorders and hyperactivity, Zilbovicius et al. [18, 19] using positive emission tomography (PET) have shown, in 76% of the children examined, a significant decrease in cerebral blood flow localized at the temporal lobe level. Taken together with the fact that intra-erythrocyte free Mg2+ is associated to increased blood pressure [20] and that brains from rats fed with a low Mg2+ diet are more susceptible to permanent brain focal ischemia [21], we can hypothesize that intracellular Mg2+ deficiency could be responsible, at least in part, for some central activity disorders observed in these children.

The duration of the treatment to get significant improvements seems to be about 8 weeks; since the cause of this deficiency is yet unknown, and since the symptoms reappeared when the Mg-B6 diet was stopped, the treatment must be maintained for a long time. In addition, while it was difficult to find an evident biological link between central disorders and Erc-Mg values, this biological parameter could be used to select, among the large population of children with hyperactive symptoms, a small population with behavioural abnormalities which is relevant to a Mg-B6 diet. It is evident that another accessible Mg2+ store, more significant for central disorders, has to be found.

Conclusion

This study brings additional information about the therapeutic role of a Mg-B6 regimen in children with ADHD. This effect seems to be associated, at least in part, to a cellular Mg2+ deficiency, as evidenced by intraerythrocyte Mg2+ measurements. Installing a Mg-B6 supplementation for some weeks restored higher intraerythrocyte Mg2+ values and significantly reduced the clinical symptoms of these diseases. As chronic magnesium deficiency was shown to be associated to hyperactivity, irritability, sleep disturbances, and poor attention at school, magnesium supplementation as well as other traditional therapeutic treatments, could be required in children with ADHD.

Acknowledgements

The authors would like to express their thanks to parents and teachers of the children included in this study for their permanent support. They are grateful to all the staff of Centre Hospitalier Universitaire of Nîmes, and to SANOFI-AVENTIS for their interest and financial support. They also thanks Dr Dominique Pradal-Prat for her constant help, and Dr Jean Durlach (Société pour le Développement des Recherches sur le Magnésium, SDRM, Paris) for his interest to our work.