subiculum

a substructure of the hippocampus, active during the retrieval of newly-learned face-name associations (but less so as retrieval became more practiced). (also see dentate gyrus and cornu ammonis)

Inflamed iron-containing cells found in Alzheimer's brains

A post-mortem study of five Alzheimer's and five control brains has revealed the presence of iron-containing microglia in the subiculum of the Alzheimer's brains only. The subiculum lies within the hippocampus, a vital memory region affected early in Alzheimer's. None of the brains of those not diagnosed with Alzheimer's had the iron deposits or the microglia, in that brain region, while four of the five Alzheimer's brains contained the iron-containing microglia.

The microglia were mostly in an inflamed state. Growing evidence implicates brain inflammation in the development of Alzheimer's.

There was no consistent association between iron-laden microglia and amyloid plaques or tau in the same area.

Obviously, this is only a small study, and more research needs to be done to confirm the finding. However, this is consistent with previous findings of higher levels of iron in the hippocampi of Alzheimer's brain.

At the moment, we don't know how the iron gets into brain tissue, or why it accumulates in the subiculum. However, the researchers speculate that it may have something to do with micro-injury to small cerebral blood vessels.

This is an interesting finding that may lead to new treatment or prevention approaches if confirmed in further research.

http://www.eurekalert.org/pub_releases/2015-07/sumc-sss072015.php

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How family circumstance impacts learning and memory in children

February, 2012

A large study shows the impact of having multiple family disadvantages on cognitive development. A brain scan study finds childhood maltreatment significantly reduces the size of the hippocampus, while another finds parental care can increase it.

Quarter of British children performing poorly due to family disadvantage

A British study involving over 18,000 very young children (aged 9 months to 5 years) has found that those exposed to two or more “disadvantages” (28% of the children) were significantly more likely to have impaired intellectual development, expressed in a significantly reduced vocabulary and behavioral problems.

These differences were significant at three, and for the most part tended to widen between ages three or five (cognitive development, hyperactivity, peer problems and prosocial behaviors; the gap didn’t change for emotional problems, and narrowed for conduct problems). However, only the narrowing of the conduct problem gap and the widening of the peer problem gap was statistically significant.

Ten disadvantages were identified: living in overcrowded housing; having a teenage mother; having one or more parents with depression, parent with a physical disability; parent with low basic skills; maternal smoking during pregnancy; excessive alcohol intake; financial stress, unemployment; domestic violence..

Around 41% of the children did not face any of these disadvantages, and 30% faced only one of these disadvantages. Of those facing two or more, half of those (14%) only had two, while 7% of the total group experienced three risk factors, and fewer than 2% had five or more.

There was no dominant combination of risks, but parental depression was the most common factor (19%), followed by parental disability (15%). Violence was present in only 4% of families, and both parents unemployed in only 5.5%. While there was some correlation between various risk factors, these correlations were relatively modest for the most part. The highest correlations were between unemployment and disability; violence and depression; unemployment and overcrowding.

There were ethnic differences in rate: at 48%, Bangladeshi children were most likely to be exposed to multiple disadvantages, followed by Pakistani families (34%), other (including mixed) (33%), black African (31%), black Caribbean (29%), white (28%) and Indian (20%).

There were also differences depending on family income. Among those in the lowest income band (below £10,400 pa) — into which 21% of the families fell, the same proportion as is found nationally — nearly half had at least two risk factors, compared to 27% of those in families above this threshold. Moreover, children in families with multiple risk factors plus low income showed the lowest cognitive development (as measured by vocabulary).

Childhood maltreatment reduces size of hippocampus

In this context, it is interesting to note a recent finding that three key areas of the hippocampus were significantly smaller in adults who had experienced maltreatment in childhood. In this study, brain scans were taken of nearly 200 young adults (18-25), of whom 46% reported no childhood adversity and 16% reported three or more forms of maltreatment. Maltreatment was most commonly physical and verbal abuse from parents, but also included corporal punishment, sexual abuse and witnessing domestic violence.

Reduced volume in specific hippocampus regions (dentate gyrus, cornu ammonis, presubiculum and subiculum) was still evident after such confounding factors as a history of depression or PTSD were taken into account. The findings support the theory that early stress affects the development of subregions in the hippocampus.

While mother’s nurturing grows the hippocampus

Supporting this, another study, involving 92 children aged 7 to 10 who had participated in an earlier study of preschool depression, has found that those children who received a lot of nurturing from their parent (generally mother) developed a larger hippocampus than those who didn’t.

‘Nurturing’ was assessed in a videotaped interaction at the time of the preschool study. In this interaction, the parent performed a task while the child waited for her to finish so they could open an attractive gift. How the parent dealt with this common scenario — the degree to which they helped the child through the stress — was evaluated by independent raters.

Brain scans revealed that children who had been nurtured had a significantly larger hippocampus than those whose mothers were not as nurturing, and (this was the surprising bit), this effect was greater among the healthy, non-depressed children. Among this group, those with a nurturing parent had hippocampi which were on average almost 10% larger than those whose parent had not been as nurturing.

Reference: 

First study:
Sabates, R., Dex, S., Sabates, R., & Dex, S. (2012). Multiple risk factors in young children’s development. CLS Cohort Studies Working paper 2012/1.
Full text available at http://www.cls.ioe.ac.uk/news.aspx?itemid=1661&itemTitle=More+than+one+i...

Second study:
[2741] Teicher, M. H., Anderson C. M., & Polcari A.
(2012).  Childhood maltreatment is associated with reduced volume in the hippocampal subfields CA3, dentate gyrus, and subiculum.
Proceedings of the National Academy of Sciences.
Full text available at http://www.pnas.org/content/early/2012/02/07/1115396109.abstract?sid=f73...

Third study:
[2734] Luby, J. L., Barch D. M., Belden A., Gaffrey M. S., Tillman R., Babb C., et al.
(2012).  Maternal support in early childhood predicts larger hippocampal volumes at school age.
Proceedings of the National Academy of Sciences.

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Specific hippocampal atrophy early sign of MCI & Alzheimer's

January, 2010
  • People with MCI who later developed Alzheimer's disease showed 10-30% greater brain atrophy in two specific regions.

A three-year study involving 169 people with mild cognitive impairment has found that those who later developed Alzheimer's disease showed 10-30% greater atrophy in two specific locations within the hippocampus, the cornu ammonis (CA1) and the subiculum. A second study comparing the brains of 10 cognitively normal elderly people and seven who were diagnosed with MCI between two and three years after their initial brain scan and with Alzheimer's some seven years after the initial scan, has confirmed the same pattern of hippocampal atrophy, from the CA1 to the subiculum, and then other regions of the hippocampus.

Reference: 

Apostolova, L.G. et al. In press. Subregional hippocampal atrophy predicts Alzheimer's dementia in the cognitively normal. Neurobiology of Aging, Available online 24 September 2008.

[392] Apostolova, L. G., Thompson P. M., Green A. E., Hwang K. S., Zoumalan C., Jack, Jr C. R., et al.
(2010).  3D comparison of low, intermediate, and advanced hippocampal atrophy in MCI.
Human Brain Mapping. 9999(9999), NA - NA.

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