Plasma levels of folates, riboflavin, vitamin B6, and ascorbate in severely disturbed children

The potential role of the antioxidant and detoxification properties of glutathione in autism spectrum disorders: a systematic review and meta-analysis

BACKGROUND

Glutathione has a wide range of functions; it is an endogenous anti-oxidant and plays a key role in the maintenance of intracellular redox balance and detoxification of xenobiotics. Several studies have indicated that children with autism spectrum disorders may have altered glutathione metabolism which could play a key role in the condition.

METHODS

A systematic literature review and meta-analysis was conducted of studies examining metabolites, interventions and/or genes of the glutathione metabolism pathways i.e. the γ-glutamyl cycle and trans-sulphuration pathway in autism spectrum disorders.

RESULTS

Thirty nine studies were included in the review comprising an in vitro study, thirty two metabolite and/or co-factor studies, six intervention studies and six studies with genetic data as well as eight studies examining enzyme activity.

CONCLUSIONS

The review found evidence for the involvement of the γ-glutamyl cycle and trans-sulphuration pathway in autistic disorder is sufficiently consistent, particularly with respect to the glutathione redox ratio, to warrant further investigation to determine the significance in relation to clinical outcomes. Large, well designed intervention studies that link metabolites, cofactors and genes of the γ-glutamyl cycle and trans-sulphuration pathway with objective behavioural outcomes in children with autism spectrum disorders are required. Future risk factor analysis should include consideration of multiple nutritional status and metabolite biomarkers of pathways linked with the γ-glutamyl cycle and the interaction of genotype in relation to these factors.

One carbon metabolism disturbances and the C677T MTHFR gene polymorphism in children with autism spectrum disorders

Autism spectrum disorders (ASDs), which include the prototypic autistic disorder (AD), Asperger’s syndrome (AS) and pervasive developmental disorders not otherwise specified (PDD-NOS), are complex neurodevelopmental conditions of unknown aetiology. The current study investigated the metabolites in the methionine cycle, the transsulphuration pathway, folate, vitamin B₁₂ and the C677T polymorphism of the MTHFR gene in three groups of children diagnosed with AD (n= 15), AS (n= 5) and PDD-NOS (n= 19) and their age- and sex-matched controls (n= 25). No metabolic disturbances were seen in the AS patients, while in the AD and PDD-NOS groups, lower plasma levels of methionine (P= 0.01 and P= 0.03, respectively) and α-aminobutyrate were observed (P= 0.01 and P= 0.001, respectively). Only in the AD group, plasma cysteine (P= 0.02) and total blood glutathione (P= 0.02) were found to be reduced. Although there was a trend towards lower levels of serine, glycine, N, N-dimethylglycine in AD patients, the plasma levels of these metabolites as well as the levels of homocysteine and cystathionine were not statistically different in any of the ASDs groups. The serum levels of vitamin B₁₂ and folate were in the normal range. The results of the MTHFR gene analysis showed a normal distribution of the C677T polymorphism in children with ASDs, but the frequency of the 677T allele was slightly more prevalent in AD patients. Our study indicates a possible role for the alterations in one carbon metabolism in the pathophysiology of ASDs and provides, for the first time, preliminary evidence for metabolic and genetic differences between clinical subtypes of ASDs.

Folate and methionine metabolism in autism: a systematic review

BACKGROUND

Autism is a complex neurodevelopmental disorder that is increasingly being recognized as a public health issue. Recent evidence has emerged that children with autism may have altered folate or methionine metabolism, which suggests the folate-methionine cycle may play a key role in the etiology of autism.

OBJECTIVE

The objective was to conduct a systematic review to examine the evidence for the involvement of alterations in folate-methionine metabolism in the etiology of autism.

DESIGN

A systematic literature review was conducted of studies reporting data for metabolites, interventions, or genes of the folate-methionine pathway in autism. Eighteen studies met the inclusion criteria, 17 of which provided data on metabolites, 5 on interventions, and 6 on genes and their related polymorphisms.

RESULTS

The findings of the review were conflicting. The variance in results can be attributed to heterogeneity between subjects with autism, sampling issues, and the wide range of analytic techniques used. Most genetic studies were inadequately powered to provide more than an indication of likely genetic relations.

CONCLUSIONS

The review concluded that further research is required with appropriately standardized and adequately powered study designs before any definitive conclusions can be made about the role for a dysfunctional folate-methionine pathway in the etiology of autism. There is also a need to determine whether functional benefits occur when correcting apparent deficits in folate-methionine metabolism in children with autism.

Metabolic biomarkers related to oxidative stress and antioxidant status in Saudi autistic children

OBJECTIVE

Measurement of oxidative stress and antioxidant-related parameters (enzymatic and non-enzymatic) in Saudi autistic children.

DESIGN AND METHODS

30 autistic children (22 males and 8 females) aged 3-15 years (25/30 of these were below 8 years old), and 30 healthy children as control group were included in this study. Levels of lipid peroxides, vitamin E, vitamin C, glutathione together with enzymatic activities of glutathione peroxidase (GSH-Px), and catalase were determined in plasma while superoxide dismutase (SOD was measured in red blood cells of both groups.

RESULTS

Lipid peroxidation was found to be significantly higher in autistic compared to control Saudi children. On the other hand, vitamin E and glutathione were remarkably lower in autistic patients while vitamin C shows non-significant lower values. Regarding the enzymatic antioxidants, both glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) were significantly higher in autistic compared to control while catalase recorded more or less similar activities in both groups.

CONCLUSION

Saudi autistic children are under H(2)O(2) stress due to GSH depletion, over expression of SOD together with the unchanged catalase enzyme. This could be helpful in the early diagnosis of young autistic patients and suggesting the possibility of antioxidant supplementation for the early intervention with autistic children.

Abnormally high plasma levels of vitamin B6 in children with autism not taking supplements compared to controls not taking supplements

BACKGROUND

There have been many studies of the effect of high-dose supplementation of vitamin B6 on children and adults with autism, with all but one reporting benefits.

OBJECTIVE

The aim of this study was to investigate the biochemical basis for vitamin B6 therapy by measuring the level of total vitamin B6 in the plasma of unsupplemented children with autism spectrum disorder compared to unsupplemented control subjects.

PARTICIPANTS

Children with autism spectrum disorders (n = 35, age 3-9 years) and unrelated typical children (n = 11, age 6-9 years), all from Arizona, were studied. (This includes the data from 24 children with autism from our previous study.)

METHODOLOGY

A microbiologic assay was used to measure the level of total vitamin B6 (including phosphorylated and unphosphorylated forms), in a blinded fashion.

RESULTS

Children with autism had a 75% higher level of total vitamin B6 than the controls (medians of 56 versus 32 ng/mL, respectively, p = 0.00002). Most of the autistic children (77%) had levels that were more than 2 standard deviations above the median value of the controls. The autistic girls (n = 5) also had elevated levels (mean of 54.6 ng/mL, median of 60 ng/mL).

DISCUSSION

These results are consistent with previous studies that found that: (1) pyridoxal kinase had a very low activity in children with autism and (2) pyridoxal 5 phosphate (PLP) levels are unusually low in children with autism. Thus, it appears that the low conversion of pyridoxal and pyridoxine to PLP results in low levels of PLP, which is the active cofactor for 113 known enzymatic reactions, including the formation of many key neurotransmitters.

CONCLUSIONS

Total vitamin B6 is abnormally high in autism, consistent with previous reports of an impaired pyridoxal kinase for the conversion of pyridoxine and pyridoxal to PLP. This may explain the many published studies of benefits of high-dose vitamin B6 supplementation in some children and adults with autism.

Serotonergic disturbances in autistic disorder: L-5-hydroxytryptophan administration to autistic youngsters increases the blood concentrations of serotonin in patients but not in controls

Some studies have suggested that disorders in the peripheral and central metabolism of serotonin (5-HT) may play a role in the pathophysiology of autistic disorder. This study examines the whole blood concentrations of 5-HT and 5-hydroxy-indoleacetic acid (5-HIAA) in baseline conditions and during a challenge with L-5-OH-tryptophane (5-HTP; 4 mg/kg in non enteric-coated tablets), the precursor of 5-HT, in a study group of 18 male, post-pubertal, Caucasian autistic patients (age 13-19 y.; I.Q.>55) and 20 matched healthy volunteers. In baseline conditions, no significant differences in 5-HT or 5-HIAA levels could be found between autistic youngsters and normal controls. 5-HTP administration significantly increased the levels of 5-HT in autistic youngsters but not in normal controls. Following 5-HTP challenge the 5-HT levels were significantly higher in autistic patients than in healthy volunteers. After challenge with 5-HTP, no significant differences were found in the concentrations of 5-HIAA or the test substance between autistic youngsters and normal controls. Differences in the peripheral metabolism of 5-HT which may not be observed in baseline conditions but which became clear after loading with 5-HTP, suggest that an increased synthesis of 5-HT from its precursor 5-HTP might be a one factor responsible for differences in the serotonergic system between autistic post-pubertal youngsters and normal controls.

Folic acid in neurodevelopment and child psychiatry

1. Folic acid deficiency has been associated with diverse neuropsychiatric symptoms. 2. This paper discusses the impact of folate on brain development, maturation and function and reviews the role of folate in psychiatric disorders, particularly childhood disorders. 3. A brief case report examines the use of folate in the treatment of attentional problems in a child with fragile X syndrome.

Infantile autism and urinary excretion of peptides and protein-associated peptide complexes

Sixty-nine early morning urine samples obtained from three groups of young adult males (autistic, mentally handicapped, and a group of men of normal intelligence) were analyzed using the methods described by Trygstad et al. (1980). No consistent patterns of urinary chromatographic profiles were identified. A number of possible contributing factors are discussed in relation to this failure to replicate the results of previous studies.