title: The consequences of paediatric mild traumatic brain injury (mTBI) on executive functioning

authors: Russ, Leanne Michelle

subjects: traumatic brain injury

abstract: Traumatic Brain Injury (TBI) is one of the most common causes of death and disability in children and adults under 35 years of age, and is a major health concern worldwide (Anderson, Catroppa, Morse, Haritou, & Rosenfeld, 2001; Babikian & Asarnow, 2009; Feigin, et al., 2013; Langlois, 2005). It is estimated 10 million people are effected worldwide annually (Hyder, Wunderlich, Puvanachandra, Gururaj, & Kobusingye, 2007), and it is projected that TBI will be the third largest cause of global disease burden by 2020 (The Lancet Neurology, 2010). Symptoms of TBI can persist across cognitive, behavioural, emotional, and social domains, regardless of age; pre-school children being particularly vulnerable, due to rapid development of the brain within the first years of life.  
The main purpose of this study (aim 1) was to determine whether mild traumatic brain injury (mTBI) injury in pre-school children had an effect on their normal cognitive development, specifically executive functioning (EF) and the sub domains of inhibitory control and working memory 24 months post injury compared with an age-matched control group. Behavioural functioning was also examined in terms of its relationship to EF (aim 2), specifically addressing both internalising and externalising behaviours and adaptability. Lastly factors that may contribute or be predictive of risk of injury were explored (aim 3), specifically age/maturation of the brain or stage of development, and both parental/environmental factors.
Forty four children participated in this population-based study; twenty two were pre-schoolers aged two years of age at the date of injury, and were assessed 24 months post injury and were aged between 4 years – 4 year 11 months.  This group was matched by age, gender, and geographical region with a TBI free control group (n=22).
Both the parent-rated Behaviour Rating Inventory of Executive Functioning (BRIEF-P) and the performance based Colour Object Interference and Day & Night tasks (COI & D&N) measures of executive functioning were used to determine any differences between the groups in terms of inhibitory control and working memory. Further parent-rated measures the Behavioural Assessment System for Children (BASC-2) and a screening test (SDQ) were also used to measure behaviour and social and emotional functioning, specifically internalising and externalising behaviour and adaptability. Other parental and environmental measures were used to determine parental mental health; The Hospital Anxiety and Depression scale (HADS), the home environment; Home Observation for Measurement of the Environment (HOME) and the parent child relationship using a parent child interaction observation task (PCI).
The study found that pre-schoolers with mTBI exhibited higher levels of internalising, and externalising problem behaviours, and poorer adaptability and EF skills, as evidenced by the associated correlations.  However analyses revealed there were no significant differences between the mTBI and control groups in terms of the measures of EF, behaviour and social and emotional functioning. These findings could suggest assessing EF in children aged between 2-5 years is difficult, or that the manifestations of the outcomes of these impairments are not yet fully observable due to young age.
The limitations of the study were the relatively small sample which was not sufficient enough to carry out regression analyses; the comparison group was not representative of the general population and lastly, the measure of the HOME was found to be out-dated and as such did not provide a comprehensive picture of the home environment. Future studies could aim to more closely examine the relationship between age at injury and outcomes from mTBI. Also they could utilise the categories within the mild severity category for a more sensitive account of the consequences of mild traumatic brain injury in children.  Therefore more research needs to be done on the effects of mild traumatic brain injury rather than focusing on hospital cohorts.

text: The consequences of paediatric mild traumatic brain injury (mTBI) on executive functioning Traumatic Brain Injury (TBI) is one of the most common causes of death and disability in children and adults under 35 years of age, and is a major health concern worldwide (Anderson, Catroppa, Morse, Haritou, & Rosenfeld, 2001; Babikian & Asarnow, 2009; Feigin, et al., 2013; Langlois, 2005). It is estimated 10 million people are effected worldwide annually (Hyder, Wunderlich, Puvanachandra, Gururaj, & Kobusingye, 2007), and it is projected that TBI will be the third largest cause of global disease burden by 2020 (The Lancet Neurology, 2010). Symptoms of TBI can persist across cognitive, behavioural, emotional, and social domains, regardless of age; pre-school children being particularly vulnerable, due to rapid development of the brain within the first years of life.  
The main purpose of this study (aim 1) was to determine whether mild traumatic brain injury (mTBI) injury in pre-school children had an effect on their normal cognitive development, specifically executive functioning (EF) and the sub domains of inhibitory control and working memory 24 months post injury compared with an age-matched control group. Behavioural functioning was also examined in terms of its relationship to EF (aim 2), specifically addressing both internalising and externalising behaviours and adaptability. Lastly factors that may contribute or be predictive of risk of injury were explored (aim 3), specifically age/maturation of the brain or stage of development, and both parental/environmental factors.
Forty four children participated in this population-based study; twenty two were pre-schoolers aged two years of age at the date of injury, and were assessed 24 months post injury and were aged between 4 years – 4 year 11 months.  This group was matched by age, gender, and geographical region with a TBI free control group (n=22).
Both the parent-rated Behaviour Rating Inventory of Executive Functioning (BRIEF-P) and the performance based Colour Object Interference and Day & Night tasks (COI & D&N) measures of executive functioning were used to determine any differences between the groups in terms of inhibitory control and working memory. Further parent-rated measures the Behavioural Assessment System for Children (BASC-2) and a screening test (SDQ) were also used to measure behaviour and social and emotional functioning, specifically internalising and externalising behaviour and adaptability. Other parental and environmental measures were used to determine parental mental health; The Hospital Anxiety and Depression scale (HADS), the home environment; Home Observation for Measurement of the Environment (HOME) and the parent child relationship using a parent child interaction observation task (PCI).
The study found that pre-schoolers with mTBI exhibited higher levels of internalising, and externalising problem behaviours, and poorer adaptability and EF skills, as evidenced by the associated correlations.  However analyses revealed there were no significant differences between the mTBI and control groups in terms of the measures of EF, behaviour and social and emotional functioning. These findings could suggest assessing EF in children aged between 2-5 years is difficult, or that the manifestations of the outcomes of these impairments are not yet fully observable due to young age.
The limitations of the study were the relatively small sample which was not sufficient enough to carry out regression analyses; the comparison group was not representative of the general population and lastly, the measure of the HOME was found to be out-dated and as such did not provide a comprehensive picture of the home environment. Future studies could aim to more closely examine the relationship between age at injury and outcomes from mTBI. Also they could utilise the categories within the mild severity category for a more sensitive account of the consequences of mild traumatic brain injury in children.  Therefore more research needs to be done on the effects of mild traumatic brain injury rather than focusing on hospital cohorts.

year: 2014

title: Book review: Seeds of Empire: The Environmental Transformation of New Zealand

authors: Beattie, James John

subjects: book review

abstract: This article reviews the book: “Book review: Seeds of Empire: The Environmental Transformation of New Zealand”, by Tom Brooking and Eric Pawson.

text: Book review: Seeds of Empire: The Environmental Transformation of New Zealand This article reviews the book: “Book review: Seeds of Empire: The Environmental Transformation of New Zealand”, by Tom Brooking and Eric Pawson.

year: 2012

title: Assessment of impacts of mechanical spat harvesting on the surf clams of Te Oneroa a Tōhē

authors: Ross, Philip M.

abstract: Much of the mussel spat used to seed mussel aquaculture farms throughout New Zealand is sourced from Te Oneroa a Tōhē (90 Mile Beach) in Te Hiku (far north of New Zealand). The mussel spat washes ashore attached to seaweed and hydroids where it is collected by spat harvesters and transported to mussel farms around the country to be on-grown. The collection of Te Hiku spat and seaweed was originally done by hand. However, the methods used have evolved over time and mussel spat is now primarily collected using mechanical loaders operating in the surf zone. Local iwi, hapu and the wider community have recently voiced their concerns about the impacts of this harvesting method. Specifically, there are concerns about the impact of loaders operating on top of toheroa (Paphies ventricosa) and tuatua (Paphies subtriangulata) beds or other shellfish inhabiting in the intertidal and subtidal areas of Te Oneroa a Tōhē. Consequently, research into the ecological impacts of mechanical spat harvesting was conducted to address the concerns of the community and inform the management of the Te Hiku spat fishery. 
This research aimed to examine the ecological impacts of a ‘worst case scenario’ by (1) simulating an intensity of spat harvesting activity much greater than would be anticipated in the ‘real world’ and (2) conducting the research at high density tuatua beds where impacts would potentially be greatest. Adult toheroa were not targeted in the experiment to avoid unnecessary impacts on already depleted toheroa populations. At each of three sites on Te Oneroa a Tōhē, nine spat harvesting loaders were repeatedly driven in and out of the surf, over shellfish beds, for 75 minutes leading up to the low tide. Once loader activity ceased, a sampling team made up of mana whenua, local primary school children, spat harvesters and staff from MPI, Te Ohu Kaimoana and the University of Waikato collected clams from the intertidal area. Collections were made from both impact and control (non-impact) sites, where (a) the number of crushed shells was quantified and (b) the self-righting and burying abilities of tuatua from impact and control areas were compared to provide an estimate of sub-lethal effects. 
There was no detectable impact of mechanical spat harvesting loaders on tuatua (or the juvenile toheroa that were present in the sampled tuatua beds) when these surf clams were either fully or partially buried in sands of Te Oneroa a Tōhē. Rates of shell damage were less 2 than 6.1% and were similar in impact and control areas indicating much of the observed shell damage was caused by the sediment corers that were used to extract samples from the beach. Similarly, being driven over by loaders did not affect the ability or speed at which tuatua were able to right and bury themselves in the sediment. When standing on end these clams appear robust to the forces exerted by loaders upon the sediment surface. However, beach cast clams (both tuatua and toheroa), lying on top of the sediment on their sides are vulnerable to crushing by vehicles. This includes juvenile clams that ‘float’ to the beach surface where multiple loader passes liquefy the surface sediment. Mortality in these beach cast clams was not well captured by the sampling methodology used in this study, but was observed at two of the three sites sampled. It was not possible to quantify this type of mortality during this study. However, the number of clams crushed on the beach surface was small relative to the high abundances of clams within the sediment and the impact is not considered ecologically significant at the scale the individual shellfish beds or the entire beach. 
Overall, there was nothing observed during the course of this experiment to suggest that mechanical harvesting is having a significant ecological effect on the toheroa or tuatua of Te Oneroa a Tōhē. Mechanical spat harvesting did result in some clam mortality during the course of this experiment, and it is likely that some mortality will occur in the future when clams are present on the beach surface. However, the level of mortality observed, and anticipated, is unlikely to compromise the viability of either clam species. 
To minimise clam mortality caused by spat harvesting, loader operators should endeavour to avoid areas where large numbers of surf clams are either beach cast or are observed washing around in the shallow subtidal. It would also be prudent, because of the depressed state of toheroa populations on Te Oneroa a Tōhē, for spat harvesters to have up-to-date information about the location of toheroa beds and avoid them where possible. 
It should be noted that concerns have been raised as to whether the driving of loaders during this study was equivalent to real world operations. However, the collection of operational data during this experiment, the proposed installation of GPS trackers on all loaders and the use of observers will allow for monitoring and enforcement of operating procedures established in the industry code of practise.

text: Assessment of impacts of mechanical spat harvesting on the surf clams of Te Oneroa a Tōhē Much of the mussel spat used to seed mussel aquaculture farms throughout New Zealand is sourced from Te Oneroa a Tōhē (90 Mile Beach) in Te Hiku (far north of New Zealand). The mussel spat washes ashore attached to seaweed and hydroids where it is collected by spat harvesters and transported to mussel farms around the country to be on-grown. The collection of Te Hiku spat and seaweed was originally done by hand. However, the methods used have evolved over time and mussel spat is now primarily collected using mechanical loaders operating in the surf zone. Local iwi, hapu and the wider community have recently voiced their concerns about the impacts of this harvesting method. Specifically, there are concerns about the impact of loaders operating on top of toheroa (Paphies ventricosa) and tuatua (Paphies subtriangulata) beds or other shellfish inhabiting in the intertidal and subtidal areas of Te Oneroa a Tōhē. Consequently, research into the ecological impacts of mechanical spat harvesting was conducted to address the concerns of the community and inform the management of the Te Hiku spat fishery. 
This research aimed to examine the ecological impacts of a ‘worst case scenario’ by (1) simulating an intensity of spat harvesting activity much greater than would be anticipated in the ‘real world’ and (2) conducting the research at high density tuatua beds where impacts would potentially be greatest. Adult toheroa were not targeted in the experiment to avoid unnecessary impacts on already depleted toheroa populations. At each of three sites on Te Oneroa a Tōhē, nine spat harvesting loaders were repeatedly driven in and out of the surf, over shellfish beds, for 75 minutes leading up to the low tide. Once loader activity ceased, a sampling team made up of mana whenua, local primary school children, spat harvesters and staff from MPI, Te Ohu Kaimoana and the University of Waikato collected clams from the intertidal area. Collections were made from both impact and control (non-impact) sites, where (a) the number of crushed shells was quantified and (b) the self-righting and burying abilities of tuatua from impact and control areas were compared to provide an estimate of sub-lethal effects. 
There was no detectable impact of mechanical spat harvesting loaders on tuatua (or the juvenile toheroa that were present in the sampled tuatua beds) when these surf clams were either fully or partially buried in sands of Te Oneroa a Tōhē. Rates of shell damage were less 2 than 6.1% and were similar in impact and control areas indicating much of the observed shell damage was caused by the sediment corers that were used to extract samples from the beach. Similarly, being driven over by loaders did not affect the ability or speed at which tuatua were able to right and bury themselves in the sediment. When standing on end these clams appear robust to the forces exerted by loaders upon the sediment surface. However, beach cast clams (both tuatua and toheroa), lying on top of the sediment on their sides are vulnerable to crushing by vehicles. This includes juvenile clams that ‘float’ to the beach surface where multiple loader passes liquefy the surface sediment. Mortality in these beach cast clams was not well captured by the sampling methodology used in this study, but was observed at two of the three sites sampled. It was not possible to quantify this type of mortality during this study. However, the number of clams crushed on the beach surface was small relative to the high abundances of clams within the sediment and the impact is not considered ecologically significant at the scale the individual shellfish beds or the entire beach. 
Overall, there was nothing observed during the course of this experiment to suggest that mechanical harvesting is having a significant ecological effect on the toheroa or tuatua of Te Oneroa a Tōhē. Mechanical spat harvesting did result in some clam mortality during the course of this experiment, and it is likely that some mortality will occur in the future when clams are present on the beach surface. However, the level of mortality observed, and anticipated, is unlikely to compromise the viability of either clam species. 
To minimise clam mortality caused by spat harvesting, loader operators should endeavour to avoid areas where large numbers of surf clams are either beach cast or are observed washing around in the shallow subtidal. It would also be prudent, because of the depressed state of toheroa populations on Te Oneroa a Tōhē, for spat harvesters to have up-to-date information about the location of toheroa beds and avoid them where possible. 
It should be noted that concerns have been raised as to whether the driving of loaders during this study was equivalent to real world operations. However, the collection of operational data during this experiment, the proposed installation of GPS trackers on all loaders and the use of observers will allow for monitoring and enforcement of operating procedures established in the industry code of practise.

year: 2020