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Postnatal delay of myelin formation in brains from Down syndrome infants and children
K E Wisniewski1, B Schmidt-Sidor
1New York State Office of Mental Retardation and Developmental Disabilities, Institute for Basic Research in Developmental Disabilities, Staten Island 10314.
Insights
Myelination is delayed in 22.5% of children with Down syndrome (DS) compared to 6.8% of non-DS children, particularly affecting fronto-temporal lobe pathways. This delay, observed between 2 months and 6 years, may correlate with developmental milestones and systemic diseases.
Area of Science:
- Neuroscience
- Developmental Biology
- Genetics
Background:
- Myelination is a critical process for nervous system development.
- Down syndrome (DS) is associated with various developmental challenges.
- Understanding myelination patterns in DS is crucial for early intervention.
Purpose of the Study:
- To investigate and compare myelination timing in fetal and postnatal brains of individuals with and without Down syndrome.
- To identify specific brain regions and tracts affected by myelination delays in DS.
- To explore potential correlations between myelination delay, systemic diseases, and developmental milestones in DS.
Main Methods:
- Comparative study of brain tissue from 129 DS cases and 73 non-DS cases (fetal and postnatal).
- Histological staining (Klüver-Barrera, Heidenhain, Loyez) of brain sections.
- Analysis of myelination timing and affected tracts, considering congenital heart disease (CHD), gastrointestinal (GI) malformations, and infections.
Main Results:
- Delayed myelination was observed in 22.5% of DS cases versus 6.8% of non-DS cases.
- Myelination delays in DS occurred between 2 months and 6 years, predominantly in fronto-temporal lobe tracts.
- No significant delay was noted in fetal or newborn DS and non-DS groups; systemic diseases and developmental milestones showed correlations with myelination delay.
Conclusions:
- Myelination is significantly delayed in a substantial proportion of individuals with Down syndrome, impacting specific brain pathways.
- The timing and extent of myelination delay in DS may be influenced by co-occurring systemic conditions and overall developmental progression.
- Further research into the mechanisms underlying myelination deficits in DS could inform therapeutic strategies.
Abstract:
Myelination up to the age of 6 years was studied in two groups consisting of 129 Down syndrome (DS) 17/129 fetuses and 112/129 postnatal) and 73 non-DS cases (10/73 fetuses and 63/73 postnatal). In both groups studied a similar number of congenital heart disease (CHD), gastrointestinal (GI) malformations and infections were diagnosed. Paraffin or celloidin brain sections were stained with Klüver-Barrera, Heidenhain or Loyez method. The myelination was found to be delayed in 29/129 (22.5%) DS and only in 5/73 (6.8%) non-DS cases. Myelination in fetuses and newborns in the DS and non-DS groups was not delayed. In DS the myelination was delayed between ages 2 months-6 years (17/29; 58.6%) up to 12 months, and 12/29 (41.4%) aged 2-6 years, while in non-DS aged 2-6 months only. The myelination delay affected tracts with late beginning and slow cycle of myelination, mainly the associated and intercortical fibers of the fronto-temporal lobes. In 3/7 of DS cases (ages 3, 4, 6 years) less advanced myelination of U fibers was noted. In both groups the myelination delay seemed also to depend on the systemic diseases which affected the subjects during the time of myelination. In DS where CHD was present the myelination delay was found in 14/29 (48.2%) in contrast to 3/5 (60%) non-DS. Also, in 28/129 (23%) DS cases dates regarding the developmental milestones were available and some correlation was found between developmental and myelination delay.(ABSTRACT TRUNCATED AT 250 WORDS)