The Role of Early-Life Conditions in the Cognitive Decline due to Adverse Events Later in Life

Cognitive functioning of elderly individuals may be affected by events such as the loss of a (grand)child or partner or the onset of a serious chronic condition, and by negative economic shocks such as job loss or the reduction of pension benefits. It is conceivable that the impact of such events is stronger if conditions early in life were adverse. In this paper we address this using a Dutch longitudinal database that follows elderly individuals for more than 15 years and contains information on demographics, socio-economic conditions, life events, health, and cognitive functioning. We exploit exogenous variation in early-life conditions as generated by the business cycle. We also examine to what extent the cumulative effect of consecutive shocks later in life exceeds the sum of the separate effects, and whether economic and health shocks later in life reinforce each other in their effect on cognitive functioning.cognitive functioning, business cycle, bereavement, developmental origins, retirement, health, long-run effects, dementia

The North Sea, past and present: shifting baselines and human uses

A clear change of species distribution in the North Sea can be deduced when comparing the maps from Olsen’s Piscatorial Atlas published in 1883 with present fish surveys. Many species have disappeared from large areas. For example, 20,000km² of oyster beds disappeared, most likely due to a combination of overfishing, possibly climate change and diseases. This had large consequences for the local biodiversity. Even in Olsen’s time, there was concern about the fishing pressure. And human pressure upon this vulnerable ecosystem keeps increasing. Apart from traditional uses such as fisheries, gas, oil and sand extraction and shipping, new functions such as wind energy, offshore protection and the possible construction of new islands are using more and more space.The first offshore wind park is now operational in The Netherlands and a large research program is being conducted concerning the possible effects of this type of park upon benthic fauna, fish, birds and sea mammals. Initial results indicate that some birds profit from the park while others avoid it. At the same time new parks are being planned, and if this continues the Dutch section of the North Sea may be strewn with small-sized wind parks in tens years time. But is this wise? Both for ecological and safety reasons it seems much better to build a few large parks instead of many small ones. And this is just on of the problems with spatial planning in the sea.For centuries, the Dutch part of the North Sea has been heavily fished. Since the 1960s a large beam trawl fleet has been harvesting sole and plaice using 4 and 12m beam trawls with tickler chains that frequently plough or rake most of the sea floor in this area. The direct effects of this type of fisheries are well known. Large amounts of unwanted by-catch are discarded and die. The long-term effects include destruction of habitats and shifts in biodiversity, species composition or age structure of benthic invertebrate and fish communities. Recent studies show clear differences between the fished and non-fished areas.The EU has asked the member states to create Marine Protected Areas (MPAs) to stop further deterioration of the marine realm. Plans for their designation are under development.In the near future, sustainability targets will have to be defined for these areas. However, the development of the marine ecosystem is the result of a very complex interplay between natural and human induced causes, the final result being an integrated summation of the effects of manageable and non-manageable factors. When managing the development of MPAs we have to take into account effects of climate change, pollution, introduced species and other drivers. In the presentation, the possible establishment of MPAs in the southern part of the North Sea and its values for spatial planning and conservation of marine biodiversity will be discussed

Responsiveness: a reinvention of the wheel?

BACKGROUND: Since the mid eighties, responsiveness is considered to be a separate property of health status questionnaires distinct from reliability and validity. The aim of the study was to assess the strength of the relationship between internal consistency reliability, referring to an instrument's sensitivity to differences in health status among subjects at one point in time, and responsiveness referring to sensitivity to health status changes over time. METHODS: We used three different datasets comprising the scores of patients on the Barthel, the SIP and the GO-QoL instruments at two points in time. The internal consistency was reduced stepwise by removing the item that contributed most to a scale's reliability. We calculated the responsiveness expressed by the Standardized Response Mean (SRM) on each set of remaining items. The strength of the relationship between the thus obtained internal consistency coefficients and SRMs was quantified by Spearman rank correlation coefficients. RESULTS: Strong to perfect correlations (0.90 – 1.00) was found between internal consistency coefficients and SRMs for all instruments indicating, that the two can be used interchangeably. CONCLUSION: The results contradict the conviction that responsiveness is a separate psychometric property. The internal consistency coefficient adequately reflects an instrument's potential sensitivity to changes over time

Practical methods for dealing with 'not applicable' item responses in the AMC Linear Disability Score project

Background:\ud Whenever questionnaires are used to collect data on constructs, such as functional status or health related quality of life, it is unlikely that all respondents will respond to all items. This paper examines ways of dealing with responses in a 'not applicable' category to items included in the AMC Linear Disability Score (ALDS) project item bank. \ud \ud Methods:\ud The data examined in this paper come from the responses of 392 respondents to 32 items and form part of the calibration sample for the ALDS item bank. The data are analysed using the one-parameter logistic item response theory model. The four practical strategies for dealing with this type of response are: cold deck imputation; hot deck imputation; treating the missing responses as if these items had never been offered to those individual patients; and using a model which takes account of the 'tendency to respond to items'. \ud \ud Results:\ud The item and respondent population parameter estimates were very similar for the strategies involving hot deck imputation; treating the missing responses as if these items had never been offered to those individual patients; and using a model which takes account of the 'tendency to respond to items'. The estimates obtained using the cold deck imputation method were substantially different. \ud \ud Conclusions:\ud The cold deck imputation method was not considered suitable for use in the ALDS item bank. The other three methods described can be usefully implemented in the ALDS item bank, depending on the purpose of the data analysis to be carried out. These three methods may be useful for other data sets examining similar constructs, when item response theory based methods are used

Beschermde gebieden Noordzee: noodzaak en mogelijkheden

This study on protected areas in the North Sea has been carried out for the Directorate of Nature, Environment and Fauna Management of the Ministry of Agriculture, Nature Management and Fisheries. It is part of a project (project number 22) of the Nature Policy Plan of this Ministry. The objective of the study, as defined by the Directorate of Nature, Environment and Fauna Management, is to review the necessity and feasibility of the designation of protected areas in the Dutch sector of the North Sea as a contribution to the conservation and, where possible, rehabilitation of a natural diversity of ecologically valuable areas with their specific communities and characteristic species. The objectives for the designation of marine protected areas are given in chapter 2 of the report: To preserve, rehabilitate and develop natural values in the Dutch sector of the North Sea by limiting the effects of those human activities that cause detectable changes in the North Sea ecosystem . To protect groups of animals which are an integral part of the natural values of the Dutch sector of the North Sea and whose existence or 'normal' functioning is currently threatened within this part of the North Sea. The study only addresses those human activities which can be controlled within the boundaries of the Dutch sector of the North Sea itself: fisheries, off-shore mining, sand and gravel extraction, military activities, shipping, pipelines and telecommunication cables. Pollution from land-based sources, atmospheric deposition, dumping and calamities have therefore not been considered in this report. Chapter 3 contains a description of the North Sea ecosystem (plankton, benthos, fish, seabirds and marine mammals). An effort was made to develop an ecological zoning for each of these groups of animals (see map on back cover). In many cases it has been possible to present relevant (a)biotic parameters. These parameters have played an important role in the final choice of protected areas. The distribution of plankton is to a large extent related to the position of water-bodies in the Dutch sector of the North Sea. The following areas can be identified: coastal water, southern North Sea, central North Sea and the Frisian Front area. The distribution of micro-, meio- and macrobenthos is largely determined by sediment types (sand, mud, gravel, stones). By and large, the following clusters can be identified with respect to infauna (macrobenthos living in the sediments) and epifauna (macrobenthos living on the seafloor): the Southern Bight including the coastal zone, Oystergrounds, Dogger Bank, the area north of the Dogger Bank, the Frisian Front area and the Klaverbank. The distribution of fish is not only determined by such factors as temperature, food, sediment type and water depth, but also by the presence of spawning and nursery areas and the location of migratory routes. With respect to seabirds, four different areas can be identified: the coastal zone, the Southern Bight, the Frisian Front area and the northern part of the Dutch sector of the North Sea. The distribution of seabirds is determined by such factors as the presence of breeding areas, migratory and wintering movements, feeding methods and availability of food. The distribution of marine mammals depends on the species. Porpoises are found both in the northern part of the Dutch sector of the North Sea and in the coastal zone north of the Frisian Islands. Dolphins are rarely seen in coastal waters. The effects of human activities in the Dutch sector of the North Sea are discussed in chapter 4 and can be summarized as follows. Fishery is a frequent large-scale activity which throughout the Dutch sector of the North Sea has resulted in considerable changes within the ecosystem. There is hardly any place where benthic communities can develop undisturbed. At least 10 benthic species have disappeared or their numbers have decreased substantially. The spawning stocks and stability of many fish stocks have decreased substantially as well. Some bird species, however, have increased in numbers. In addition, intensive fisheries have possibly contributed to the decline of sea mammal populations. Offshore mining can, as a result of discharges of cuttings contaminated with oil-based muds (OBM), result in long-term local effects on the benthic system. Effects of water-based muds (WBM) cannot be ruled out, but will be found in smaller areas over a shorter period of time than the effects of OBM. Effects of discharges of production water have not been observed but could occur locally with effects on plankton, fish and birds. It seems unlikely that acoustic disturbance by offshore mining (including seismic surveys) should affect sea mammals which are more that 100 m away from the installation producing the disturbance. Some disturbance may occur as a result of ship and helicopter movements associated with offshore mining. Sand and gravel extraction and the laying of pipelines and telecommunication cables will result in local effects on the benthic system. The destruction of shellfish beds in the coastal zone by sand or gravel extraction might have long-term effects on scoters. It is not possible to quantify the effects of substances introduced into the marine environment by shipping and military activities. Noise produced by such activities may affect communication between sea mammals and behaviour of seabirds. There may be a recovery of those populations which are affected by fisheries. discharges from mining installations, sand and gravel extraction and the laying of pipelines and telecommunication cables after termination of these activities in certain parts of the Dutch sector of the North Sea. This would contribute to the recovery and conservation of these populations in the North Sea in general (see chapter 5). In general, recovery of communities may take 1 to 20 years (benthos and fish), 5 to 50 years (for seabirds) and 20 to more then 50 years (for sea mammals). Recovery will be impossible if gravel extraction has resulted in the removal of the entire layer of gravel on the seafloor. Chapters 6 and 7 give the objectives and related criteria which are used for the designation and the selection of areas which qualify for a protected status. The first criterion addresses the extent to which specific activities have developed into a threat to the existence or normal functioning of groups of animals or species in the Dutch sector of the North Sea. Fishery activities result in large-scale effects on a large number of ecological groups (benthos, fish, seabirds, marine mammals) in the Dutch sector of the North Sea. Discharges of cuttings contaminated with OBM result in long-term local benthic effects. Other discharges by offshore mining installations and sand and gravel extraction have local but possibly large-scale effects on benthos in specific relatively small areas such as the Frisian Front area or the Klaverbank. The second criterion addresses the question whether a prohibition or restriction of certain human activities in specific areas would reduce the threat to those groups of animals or species which were identified through the application of the first criterion. Alternatives for prohibitive or restrictive measures are also discussed. The designation of protected areas where certain activities are prohibited or restricted has the potential to contribute to the conservation or recovery of threatened species. In a number of cases there is no alternative other than the designation of protected areas. This is true of the threat to the benthos and fish which is caused by fisheries activities in the (Dutch sector of the) North Sea, and, in specific relatively small areas, it is also true of the threat to benthos caused by discharges from offshore mining installations and by sand and gravel extraction. The third criterion is used for identifying the areas most suitable for a protected Status on the basis of the ecology of groups of animals or species which need protection. Ecological criteria such as diversity, representativeness. integrity and vulnerability have been used. The application of ecological criteria results in the general conclusion that, within the Dutch sector of the North Sea, the following types of areas qualify for a protected status: a sandy area, a muddy area, an area with frontal characteristics and a gravel area. A protected area should contain coastal waters and an adequate depth gradient. An unbroken area which contains areas of all types would be the most effective option for protection. For the protection of benthos species with a limited migration, areas of circa one hundred square kilometers each should be sufficient; for fish species with an extensive migration pattern it would be necessary to protect a large part of the whole North Sea. It is concluded that for the protection of those species which are most characteristic of the Dutch sector of the North Sea it is necessary to protect an area with a total surface of some 31 ICES blocks (each some 60 x 60 square kilometers). The fourth criterion addresses the question whether there are adequate legal instruments to ensure effective protection of the selected areas. On the basis of existing legal instruments it is, in principle, possible to protect these areas. However; there are certain problems associated with measures which are required with respect to fisheries, gravel extraction and offshore mining. On the basis of the above criteria it is concluded that two areas within the Dutch sector of the North Sea qualify for a protected status: 1. An area directly northwest of the Frisian Islands (see Figs A and B). In this unbroken area of some 10,000 square kilometers it will be possible to protect a combination of different types of benthic communities (coastal waters, sandy bottoms, the Frisian Front area, muddy areas and restricted areas with gravel and stones). The area will also have an adequate depth gradient. The proposed area contains important spawning and nursery areas for fish (including squid) and habitats of many (non-commercial) fish species. Seasonal migratory routes to and from the Wadden Sea are concentrated in this area. Relatively large numbers of porpoises as well as dolphins and seabirds occur in this area. Protection of this area also strengthens the functioning of the Wadden Sea as a nursery area and supports the recolonisation of benthos in the Wadden Sea after, for instance, severe winters. There are two alternative options for the exact location of the area to be protected. The first alternative (Fig. A) has been chosen especially with an emphasis on conservation and recovery of the diversity of communities in the Dutch sector of the North Sea. The second alternative (Fig. B) more closely relates to existing measures regarding fisheries. The proportion of muddy areas is very low in this alternative. An expansion of the proposed area in an easterly direction could be considered only if it connected the area with similar protected areas in the German sector of the North Sea. An expansion of the proposed area in a southerly direction would more closely relate to the ecological interests of the Wadden Sea. The following protective measures are proposed for this area: The area will be closed for all types of fisheries throughout the year; Discharges from offshore mining installations which contain oil will be prevented (OBM) or minimized (production water); Additional area-specific protective measures with respect to offshore mining, shipping, military activities, sand extraction, dumping and the laying of pipelines can be considered whenever the situation in this area calls for such measures. Such measures should also be considered for areas to be used as reference areas for scientific research; The application of policies resulting from the implementation of international conventions with respect to conservation (the EC Bird Directive, the Conventions of Bonn, Berne and Ramsar, the proposed EC Habitat Directive). 2. Klaverbank (see Figs A and B). The Klaverbank, the only gravel area of importance in the Dutch sector of the North Sea, has a still relatively undisturbed benthic fauna which is specific to this type of area. The Klaverbank (approximately 800 square kilometers) should be given a protected status under which gravel extraction is prohibited. and discharges from offshore mining installations which contain oil will be prevented (OBM) or minimized (production water). Fisheries too should be prohibited but the limited size of this area rules out effective implementation and enforcement of such a measure. It is therefore advisable to develop proposals in cooperation with the United Kingdom for the designation of a protected area in the UK sector of the North Sea which should contain a large gravel area and possibly also the Klaverbank. If a decision is taken to protect these areas, it will be necessary to develop a management plan. Chapter 8 gives a possible outline for such a management plan, including certain relevant issues. Firstly, it will be necessary to define objectives for these specific areas in addition to the objectives already defined for the designation of protected areas in general. Secondly, it will be necessary to attune measures for the management of these areas to the objectives of their protection. A management plan will also have to address the organizational structure required for effective management of these areas. Arrangements for adequate enforcement and effective control of measures taken are also necessary. Programmes for scientific research will have to be developed

Laboratory study of the impact of repetitive electrical and mechanical stimulation on brown shrimp Crangon crangon

Pulse trawling is currently the best available alternative to beam trawling in the brown shrimp Crangon crangon and Sole Solea solea (also known as Solea vulgaris) fisheries. To evaluate the effect of repetitive exposure to electrical fields, brown shrimp were exposed to the commercial electrodes and pulse settings used to catch brown shrimp (shrimp startle pulse) or Sole (Sole cramp pulse) 20 times in 4 d and monitored for up to 14 d after the first exposure. Survival, egg loss, molting, and the degree of intranuclear bacilliform virus (IBV) infection were evaluated and compared with those in stressed but not electrically exposed (procedural control) and nonstressed, nonexposed (control) brown shrimp as well as brown shrimp exposed to mechanical stimuli. The lowest survival at 14 d (57.3%) occurred in the Sole cramp pulse treatment, and this was significantly lower than in the group with the highest survival, the procedural control (70.3%). No effect of electrical stimulation on the severity of IBV infection was found. The lowest percentage of molts occurred in the repetitive mechanical stimulation treatment (14.0%), and this was significantly lower than in the group with the highest percentage of molts, the procedural control (21.7%). Additionally, the mechanically stimulated brown shrimp that died during the experiment had a significantly larger size than the surviving individuals. Finally, no effect of the shrimp startle pulse was found. Therefore, it can be concluded that repetitive exposure to a cramp stimulus and mechanical stimulation may have negative effects on the growth and/or survival of brown shrimp. However, there is no evidence that electrical stimulation during electrotrawls would have a larger negative impact on brown shrimp stocks than mechanical stimulation during conventional beam trawling