Cognitive Functioning in Alcohol and Other Substance Use Disorders in Young Adulthood : A Genetic Epidemiological Study

Alcohol and other substance use disorders (SUDs) result in great costs and suffering for individuals and families and constitute a notable public health burden. A multitude of factors, ranging from biological to societal, are associated with elevated risk of SUDs, but at the level of individuals, one of the best predictors is a family history of SUDs. Genetically informative twin and family studies have consistently indicated this familial risk to be mainly genetic. In addition, behavioral and temperamental factors such as early initiation of substance use and aggressiveness are associated with the development of SUDs. These familial, behavioral and temperamental risk factors often co-occur, but their relative importance is not well known. People with SUDs have also been found to differ from healthy controls in various domains of cognitive functioning, with poorer verbal ability being among the most consistent findings. However, representative population-based samples have rarely been used in neuropsychological studies of SUDs. In addition, both SUDs and cognitive abilities are influenced by genetic factors, but whether the co-variation of these traits might be partly explained by overlapping genetic influences has not been studied. Problematic substance use also often co-occurs with low educational level, but it is not known whether these outcomes share part of their underlying genetic influences. In addition, educational level may moderate the genetic etiology of alcohol problems, but gene-environment interactions between these phenomena have also not been widely studied. The incidence of SUDs peaks in young adulthood rendering epidemiological studies in this age group informative. This thesis investigated cognitive functioning and other correlates of SUDs in young adulthood in two representative population-based samples of young Finnish adults, one of which consisted of monozygotic and dizygotic twin pairs enabling genetically informative analyses. Using data from the population-based Mental Health in Early Adulthood in Finland (MEAF) study (n=605), the lifetime prevalence of DSM-IV any substance dependence or abuse among persons aged 21—35 years was found to be approximately 14%, with a majority of the diagnoses being alcohol use disorders. Several correlates representing the domains of behavioral and affective factors, parental factors, early initiation of substance use, and educational factors were individually associated with SUDs. The associations between behavioral and affective factors (attention or behavior problems at school, aggression, anxiousness) and SUDs were found to be largely independent of factors from other domains, whereas daily smoking and low education were still associated with SUDs after adjustment for behavioral and affective factors. Using a wide array of neuropsychological tests in the MEAF sample and in a subsample (n=602) of the population-based FinnTwin16 (FT16) study, consistent evidence of poorer verbal cognitive ability related to SUDs was found. In addition, participants with SUDs performed worse than those without disorders in a task assessing psychomotor processing speed in the MEAF sample, whereas no evidence of more specific cognitive deficits was found in either sample. Biometrical structural equation models of the twin data suggested that both alcohol problems and verbal ability had moderate heritabilities (0.54—0.72), and that their covariation could be explained by correlated genetic influences (genetic correlations -0.20 to -0.31). The relationship between educational level and alcohol problems, studied in the full epidemiological FT16 sample (n=4,858), was found to reflect both genetic correlation and gene-environment interaction. The co-occurrence of low education and alcohol problems was influenced by overlapping genetic factors. In addition, higher educational level was associated with increased relative importance of genetic influences on alcohol problems, whereas environmental influences played a more important role in young adults with lower education. In conclusion, SUDs, especially alcohol abuse and dependence, are common among young Finnish adults. Behavioral and affective factors are robustly related to SUDs independently of many other factors, and compared to healthy peers, young adults who have had SUDs during their life exhibit significantly poorer verbal cognitive ability, and possibly less efficient psychomotor processing. Genetic differences between individuals explain a notable proportion of individual differences in risk of alcohol dependence, verbal ability, and educational level, and the co-occurrence of alcohol problems with poorer verbal cognition and low education is influenced by shared genetic backgrounds. Finally, various environmental factors related to educational level in young adulthood moderate the relative importance of genetic factors influencing the risk of alcohol problems, possibly reflecting differences in social control mechanisms related to educational level.

Associations of interleukin-1 (IL-1) gene variation and IL-1 receptor antagonist phenotypes with immunological responses, metabolic dysregulation and type 2 diabetes

The upstream proinflammatory interleukin-1 (IL-1) cytokines, together with a naturally occurring IL-1 receptor antagonist (IL-1Ra), play a significant role in several diseases and physiologic conditions. The IL-1 proteins affect glucose homeostasis at multiple levels contributing to vascular injuries and metabolic dysregulations that precede diabetes. An association between IL-1 gene variations and IL-1Ra levels has been suggested, and genetic studies have reported associations with metabolic dysregulation and altered inflammatory responses. The principal aims of this study were to: 1) examine the associations of IL-1 gene variation and IL-1Ra expression in the development and persistence of thyroid antibodies in subacute thyroiditis; 2) investigate the associations of common variants in the IL-1 gene family with plasma glucose and insulin concentrations, glucose homeostasis measures and prevalent diabetes in a representative population sample; 3) investigate genetic and non-genetic determinants of IL-1Ra phenotypes in a cross-sectional setting in three independent study populations; 4) investigate in a prospective setting (a) whether variants of the IL-1 gene family are predictors for clinically incident diabetes in two population-based observational cohort studies; and (b) whether the IL-1Ra levels predict the progression of metabolic syndrome to overt diabetes during the median follow-up of 10.8 and 7.1 years. Results from on patients with subacte thyroiditis showed that the systemic IL-1Ra levels are elevated during a specific proinflammatory response and they correlated with C-reactive protein (CRP) levels. Genetic variation in the IL-1 family seemed to have an association with the appearance of thyroid peroxidase antibodies and persisting local autoimmune responses during the follow-up. Analysis of patients suffering from diabetes and metabolic traits suggested that genetic IL-1 variation and IL-1Ra play a role in glucose homeostasis and in the development of type 2 diabetes. The coding IL-1 beta SNP rs1143634 was associated with traits related to insulin resistance in cross-sectional analyses. Two haplotype variants of the IL-1 beta gene were associated with prevalent diabetes or incident diabetes in a prospective setting and both of these haplotypes were tagged by rs1143634. Three variants of the IL-1Ra gene and one of the IL-1 beta gene were consistently identified as significant, independent determinants of the IL-1Ra phenotype in two or three populations. The proportion of the phenotypic variation explained by the genetic factors was modest however, while obesity and other metabolic traits explained a larger part. Body mass index was the strongest predictor of systemic IL-1Ra concentration overall. Furthermore, the age-adjusted IL-1Ra concentrations were elevated in individuals with metabolic syndrome or diabetes when compared to those free of metabolic dysregulation. In prospective analyses the systemic IL-1Ra levels were found as independent predictors for the development of diabetes in people with metabolic syndrome even after adjustment for multiple other factors, including plasma glucose and CRP levels. The predictive power of IL-1Ra was better than that of CRP. The prospective results also provided some evidence for a role of common IL-1 alpha promoter SNP rs1800587 in the development of type 2 diabetes among men and suggested that the role may be gender specific. Likewise, common variations in the IL-1 beta coding region may have a gender specific association with diabetes development. Further research on the potential benefits of IL-1Ra measurements in identifying individuals at high risk for diabetes, who then could be targeted for specific treatment interventions, is warranted. It has been reported in the recent literature that IL-1Ra secreted from adipose tissue has beneficial effects on glucose homeostasis. Furthermore, treatment with recombinant human IL-1Ra has been shown to have a substantial therapeutic potential. The genetic results from the prospective analyses performed in this study remain inconclusive, but together with the cross-sectional analyses they suggest gender-specific effects of the IL-1 variants on the risk of diabetes. Larger studies with more extensive genotyping and resequencing may help to pinpoint the exact variants responsible and to further elucidate the biological mechanisms for the observed associations. This would improve our understanding of the pathways linking inflammation and obesity with glucose and insulin metabolism.

Impact of agricultural market liberalization on food security in developing countries : a comparative study of Kenya and Zambia

This research investigates the impacts of agricultural market liberalization on food security in developing countries and it evaluates the supply perspective of food security. This research theme is applied on the agricultural sector in Kenya and in Zambia by studying the role policies played in the maize sub-sector. An evaluation of selected policies introduced at the beginning of the 1980s is made, as well as an assessment of whether those policies influenced maize output. A theoretical model of agricultural production is then formulated to reflect cereal production in a developing country setting. This study begins with a review of the general framework and the aims of the structural adjustment programs and proceeds to their application in the maize sector in Kenya and Zambia. A literature review of the supply and demand synthesis of food security is presented with examples from various developing countries. Contrary to previous studies on food security, this study assesses two countries with divergent economic orientations. Agricultural sector response to economic and institutional policies in different settings is also evaluated. Finally, a dynamic time series econometric model is applied to assess the effects of policy on maize output. The empirical findings suggest a weak policy influence on maize output, but the precipitation and acreage variables stand out as core determinants of maize output. The policy dimension of acreage and how markets influence it is not discussed at length in this study. Due to weak land rights and tenure structures in these countries, the direct impact of policy change on land markets cannot be precisely measured. Recurring government intervention during the structural policy implementation period impeded efficient functioning of input and output markets, particularly in Zambia. Input and output prices of maize and fertilizer responded more strongly in Kenya than in Zambia, where the state often ceded to public pressure by revoking pertinent policy measures. These policy interpretations are based on the response of policy variables which are more responsive in Kenya than in Zambia. According the obtained regression results, agricultural markets in general, and the maize sub-sector in particular, responded more positively to implemented policies in Kenya, than in Zambia, which supported a more socialist economic system. It is observed in these results that in order for policies to be effective, sector and regional dimensions need to be considered. The regional and sector dimensions were not taken into account in the formulation and implementation of structural adjustment policies in the 1980s. It can be noted that countries with vibrant economic structures and institutions fared better than those which had a firm, socially founded system.

United We Stand - Divided We Fall : A Standard Model of Unit Cohesion

Research on unit cohesion has shown positive correlations between cohesion and valued outcomes such as strong performance, reduced stress, less indiscipline, and high re-enlistment intentions. However, the correlations have varied in strength and significance. The purpose of this study is to show that taking into consideration the multi-component nature of cohesion and relating the most applicable components to specific outcomes could resolve much of the inconsistency. Unit cohesion is understood as a process of social integration among members of a primary group with its leaders, and with the larger secondary groups of which they are a part. Correspondingly, included in the framework are four bonding components: horizontal (peer) and vertical (subordinate and leader) and organizational and institutional, respectively. The data were collected as part of a larger research project on cohesion, leadership, and personal adjustment to the military. In all, 1,534 conscripts responded to four questionnaires during their service in 2001-2002. In addition, sociometric questionnaires were given to 537 group members in 47 squads toward the end of their service. The results showed that platoons with strong primary-group cohesion differed from other platoons in terms of performance, training quality, secondary-group experiences, and attitudes toward refresher training. On the sociometric level it was found that soldiers who were chosen as friends by others were more likely to have higher expected performance, better performance ratings, more positive attitudes toward military service, higher levels of well-being during conscript service, and fewer exemptions from duty during it. On the group level, the selection of the respondents own group leader rather than naming a leader from outside (i.e., leader bonding) had a bearing not only on cohesion and performance, but also on the social, attitudinal, and behavioral criteria. Overall, the aim of the study was to contribute to the research on cohesion by introducing a model that takes into account the primary foci of bonding and their impact. The results imply that primary-group and secondary-group bonding processes are equally influential in explaining individual and group performance, whereas the secondary-group bonding components are far superior in explaining career intentions, personal growth, avoidance of duty, and attitudes toward refresher training and national defense. This should be considered in the planning and conducting of training. The main conclusion is that the different types of cohesion components have a unique, positive, significant, but varying impact on a wide range of criteria, confirming the need to match the components with the specific criteria.

Anger is associated with subclinical atherosclerosis in low SES but not in higher SES men and women

We investigated the associations of anger and cynicism with carotid artery intima-media thickness (IMT) and whether these associations were moderated by childhood or adulthood socioeconomic status (SES). The participants were 647 men and 893 women derived from the population-based Cardiovascular Risk in Young Finns Study. Childhood SES was measured in 1980 when the participants were aged 3-18. In 2001, adulthood SES, anger, cynicism, and IMT were measured. There were no associations between anger or cynicism and IMT in the entire population, but anger was associated with thicker IMT in participants who had experienced low SES in childhood. This association persisted after adjustment for a host of cardiovascular risk factors. It is concluded that the ill health-effects of psychological factors such as anger may be more pronounced in individuals who have been exposed to adverse socioeconomic circumstances early in life.

Modelling initial survival and growth of radiata pine in New Zealand.

A sensitive framework has been developed for modelling young radiata pine survival, its growth and its size class distribution, from time of planting to age 5 or 6 years. The data and analysis refer to the Central North Island region of New Zealand. The survival function is derived from a Weibull probability density function, to reflect diminishing mortality with the passage of time in young stands. An anamorphic family of trends was used, as very little between-tree competition can be expected in young stands. An exponential height function was found to fit best the lower portion of its sigmoid form. The most appropriate basal area/ha exponential function included an allometric adjustment which resulted in compatible mean height and basal area/ha models. Each of these equations successfully represented the effects of several establishment practices by making coefficients linear functions of site factors, management activities and their interactions. Height and diameter distribution modelling techniques that ensured compatibility with stand values were employed to represent the effects of management practices on crop variation. Model parameters for this research were estimated using data from site preparation experiments in the region and were tested with some independent data sets.

Late-industrial sawmill customers.

The methods of secondary wood processing are assumed to evolve over time and to affect the requirements set for the wood material and its suppliers. The study aimed at analysing the industrial operating modes applied by joinery and furniture manufacturers as sawnwood users. Industrial operating mode was defined as a pattern of important decisions and actions taken by a company which describes the company's level of adjustment in the late-industrial transition. A non-probabilistic sample of 127 companies was interviewed, including companies from Denmark, Germany, the Netherlands, and Finland. Fifty-two of the firms were furniture manufacturers and the other 75 were producing windows and doors. Variables related to business philosophy, production operations, and supplier choice criteria were measured and used as a basis for a customer typology; variables related to wood usage and perceived sawmill performance were measured to be used to profile the customer types. Factor analysis was used to determine the latent dimensions of industrial operating mode. Canonical correlations analysis was applied in developing the final base for classifying the observations. Non-hierarchical cluster analysis was employed to build a five-group typology of secondary wood processing firms; these ranged from traditional mass producers to late-industrial flexible manufacturers. There is a clear connection between the amount of late-industrial elements in a company and the share of special and customised sawnwood it uses. Those joinery or furniture manufacturers that are more late-industrial also are likely to use more component-type wood material and to appreciate customer-oriented technical precision. The results show that the change is towards the use of late-industrial sawnwood materials and late-industrial supplier relationships.

Visuaalisen työmuistin vapaasti jaettavat resurssit : muistiedustusten lukumäärä ja tarkkuus ääriviivakuvioilla

According to the most prevalent view, there are 3-4 fixed "slots" in visual working memory for temporary storage. Recently this view has been challenged with a theory of dynamic resources which are restricted in their totality but can be freely allocated. The aim of this study is to clarify which one of the theories better describes the performance in visual working memory tasks with contour shapes. Thus in this study, the interest is in both the number of recalled stimuli and the precision of the memory representations. Stimuli in the experiments were radial frequency patterns, which were constructed by sinusoidally modulating the radius of a circle. Five observers participated in the experiment and it consisted of two different tasks. In the delayed discrimination task the number of recalled stimuli was measured with 2-interval forced choice task. Observer was shown serially two displays with 1, 5 s ISI (inter stimulus interval). Displays contained 1-6 patterns and they differed from each other with changed amplitude in one pattern. The participant s task was to report whether the changed pattern had higher amplitude in the first or in the second interval. The amount of amplitude change was defined with QUEST-procedure and the 75 % discrimination threshold was measured in the task. In the recall task the precision of the memory representations was measured with subjective adjustment method. First, observer was shown 1-6 patterns and after 1, 5 s ISI one location of the previously shown pattern was cued. Observer s task was to adjust amplitude of a probe pattern to match the amplitude of the pattern in working memory. In the delayed discrimination task the performance of all observes declined smoothly when the number of presented patterns was increased. The result supports the resource theory of working memory as there was no sudden fall in the performance. The amplitude threshold for one item was 0.01 0.05 and as the number of items increased from 1 to 6 there was a 4 15 -fold linear increase in the amplitude threshold (0.14 0.29). In the recall adjustment task the precision of four observers performance declined smoothly as the number of presented patterns was increased. The result also supports the resource theory. The standard deviation for one item was 0.03 0.05 and as the number of items increased from 1 to 6 there was a 2 3 -fold linear increase in the amplitude threshold (0.06 0.11). These findings show that the performance in a visual working memory task is described better according to the theory of freely allocated resources and not to the traditional slot-model. In addition, the allocation of the resources depends on the properties of the individual observer and the visual working memory task.

Desorptio/fotoionisaatio ilmanpaineessa takavarikoitujen huumausaineiden, steroidien ja räjähdysaineiden tutkimuksessa

Tutkimuksen tarkoituksena oli selvittää desorptio/fotoionisaatio ilmanpaineessa tekniikan (engl. desorption atmospheric pressure photoionization, DAPPI) soveltuvuutta rikosteknisen laboratorion näytteiden analysointiin. DAPPI on nopea massaspektrometrinen ionisaatiotekniikka, jolla voidaan tutkia yhdisteitä suoraan erilaisilta pinnoilta. DAPPI:ssa käytetään lämmitettyä mikrosirua, joka suihkuttaa höyrystynyttä liuotin- ja kaasuvirtausta kohti näytettä. Näytteen pinnan komponentit desorboituvat lämmön vaikutuksesta, jonka jälkeen ionisoituminen tapahtuu VUV-lampun emittoimien fotonien avulla.DAPPI:lla tutkittiin takavarikoituja huumausaineita, anabolisia steroideja ja räjähdysaineita sekä niiden jäämiä erilaisilta pinnoilta. Lisäksi kartoitettiin DAPPI:n mahdollisuuksia ja rajoituksia erilaisille näytematriiseille ilman näytteiden esikäsittelyä. Takavarikoitujen huumausaineiden tutkimuksessa analysoitiin erilaisia tabletteja, jauheita, kasvirouheita, huumekasveja (khat, oopium, kannabis) ja sieniä. Anabolisia steroideja tunnistettiin tableteista sekä ampulleista, jotka sisälsivät öljymäistä nestettä. Jauheet ripoteltiin kaksipuoliselle teipille ja analysoitiin siltä. Muut näytteet analysoitiin sellaisenaan ilman minkäänlaista esikäsittelyä, paitsi nestemäisten näytteiden kohdalla näyte pipetoitiin talouspaperille, joka analysoitiin DAPPI:lla. DAPPI osoittautui nopeaksi ja yksinkertaiseksi menetelmäksi takavarikoitujen huumausaineiden ja steroidien analysoimisessa. Se soveltui hyvin rikoslaboratorion erityyppisten näytteiden rutiiniseulontaan ja helpotti erityisesti huumekasvien ja öljymäisten steroidiliuosten tutkimusta. Massaspektrometrin likaantuminen pystyttiin ehkäisemään säätämällä näytteen etäisyyttä sen suuaukosta. Likaantumista ei havaittu huolimatta näytteiden korkeista konsentraatioista ja useita kuukausia jatkuneista mittauksista. Räjähdysaineiden tutkimuksessa keskityttiin seitsemän eri räjähdysaineen DAPPI-MS-menetelmän kehitykseen; trinitrotolueeni (TNT), nitroglykoli (NK), nitroglyseriini (NG), pentriitti (PETN), heksogeeni (RDX), oktogeeni (HMX) ja pikriinihappoä Nämä orgaaniset räjähteet ovat nitraattiyhdisteitä, jotka voidaan jakaa rakenteen puolesta nitroamiineihin (RDX ja HMX), nitroaromaatteihin (TNT ja pikriinihappo) sekä nitraattiestereihin (PETN, NG ja NK). Menetelmäkehityksessä räjähdysainelaimennokset pipetoitiin polymetyylimetakrylaatin (PMMA) päälle ja analysoitiin siitä. DAPPI:lla tutkittiin myäs autenttisia räjähdysainejäämiä erilaisista matriiseista. DAPPI:lla optimoitiin jokaiselle räjähdysaineelle sopiva menetelmä ja yhdisteet saatiin näkymään puhdasaineina. Räjähdysainejäämien analysoiminen erilaisista rikospaikkamateriaaleista osoittautui haastavammaksi tehtäväksi, koska matriisit aiheuttivat itsessään korkean taustan spektriin, josta räjähdysaineiden piikit eivät useimmiten erottuneet tarpeeksi. Muut desorptioionisaatiotekniikat saattavat soveltua paremmin haastavien räjähdysainejäämien havaitsemiseksi.

Behavioural responses to anthropogenic disturbances

When a habitat undergoes change, the first response of an individual is often behavioural adjustment. This immediate response can determine whether the population will survive or not, as behavioural flexibility gives time for genetic changes to arise later on. Habitat changes that alter reproductive behaviours can have long-lasting effects on populations. If the selective regime has changed under the new conditions, mate choice cues may no longer reliably reflect an individual s quality. Thus, animals have to be able to adjust their reproductive behaviours to the local conditions. The aim of my thesis was to discuss if and how animals are able to respond to rapid anthropogenic environmental change, and to study the mechanisms of the responses and the evolutionary consequences. The main focus was on the effects of human-induced eutrophication on the reproductive behaviour of fishes. Eutrophication is the result of increased nutrient input and can cause dense underwater vegetation and algal blooms. I used fishes from two very different ecosystems as model species, the Baltic Sea threespine stickleback (Gasterosteus aculeatus) and the desert goby (Chlamydogobius eremius), an endemic species of the Lake Eyre region in Central Australia. I investigated the effects of increased habitat complexity on courtship behaviour and the possibility of local differentiation in courtship and nest building behaviour depending on the level eutrophication in the habitat of origin. Furthermore, I observed the effect of turbidity on stickleback nest building behaviour. The results show that threespine stickleback males, which were born in areas that have been eutrophied for decades, court females at a higher intensity than males from clear water areas. Similarly, male desert gobies increased their courtship effort in dense vegetation. Intense courtship could be an adjustment to reduced visibility and lowered predation risk in the densely vegetated sites. However, there were no clear differences in nest building between males from clear and eutrophied areas under standardized conditions. This was expected as Baltic Sea sticklebacks prefer to nest under vegetation cover and are fairly rigid in adjusting their nest characteristics. Nest building was affected by increased turbidity: males built smaller nests with a larger nest entrance in turbid water. The large variation in the magnitude of phytoplankton blooms may require a rapid adjustment of the optimal nest structure to the current conditions. This thesis highlights the complex interactions that are set- off by human-induced changes in habitats and are followed by the immediate behavioural responses. It also encourages more research to tease apart the phenotypic and genetic components of the observed behavioural differences.

Taulukkoaineistojen tilastolliset tietosuojamenetelmät

Tutkielmassa käsitellään taulukkoaineistoihin liittyviä tilastollisia tietosuojakysymyksiä, kuten milloin julkaistavan taulukkoaineiston tilastoyksiköihin kohdistuu paljastumisriski ja millä menetelmillä tätä riskiä voidaan pienentää. Taulukkoaineistojen tilastollisia tietosuojamenetelmiä on tutkittu jo kymmeniä vuosia, mutta edelleen niiden soveltamiseen liittyy haasteita ja ratkaisemattomia kysymyksiä. Taulukkoaineistolla tai taulukolla tarkoitetaan tässä tutkielmassa taulukkomuotoon järjestettyä aggregoitua aineistoa. Yhteiskunta tarvitsee toimiakseen luotettavia tilastotietoja ja tilastoviranomaisten tehtävä on tuottaa niitä. Taulukko on perinteinen muoto julkaista tilastotietoja, joten niille on välttämätön tarve. Paitsi lainsäädäntö, myös tilastoalan eettiset periaatteet edellyttävät tilastoinnin kohteiden yksityisyyden suojaamista. Taulukkoaineisto on näin ollen suojattava ennen julkaisua, jos taulukkoon kohdistuu paljastumisriski. Taulukon paljastumisriski määritellään solukohtaisen paljastumisriskin avulla: taulukkoon kohdistuu riski, jos yhteenkin sen soluun kohdistuu riski. Soluun kohdistuu paljastumisriski, jos yksikin siihen kuuluva tilastoyksikkö on vaarassa paljastua julkaistun taulukon avulla. Paljastumisriskiä ei kokonaan voida poistaa, mutta tilastollisilla tietosuojamenetelmillä se pyritään laskemaan hyväksyttävälle tasolle. Tilastolliset tietosuojamenetelmät muokkaavat aineistoa rajoittamalla, muuntamalla tai korvaamalla, jolloin tietoa väistämättä menetetään. Samalla aineiston laatu, oikeellisuus, tarkkuus, täydellisyys ja käytettävyys kärsivät. Eri menetelmiä sovellettaessa eri määrä informaatiota häviää. Oikean tietosuojamenetelmän valinnassa tärkeimmät kriteerit ovat vaaditun suojaustason saavuttaminen ja taulukon tärkeiden analyyttisten ominaisuuksien säilyminen. Haasteena on löytää kunkin taulukon kohdalla oikea tasapaino tilastoyksiköihin kohdistuvan paljastumisriskin sekä menetetyn tiedon ja hyödyn välillä. Tilastollinen tietosuoja on haastava tilastotieteen osa-alue, koska jokaisella suojattavalla tilastolla on omat huomioonotettavat erityispiirteensä. Voidaan sanoa, että jokainen tilasto muodostaa suojaamisen kannalta oman erikoistapauksensa. Paljastumisriskiä ja erilaisia tilastollisia tietosuojamenetelmiä käsitellään tutkielmassa ensin teoreettisesti. Teoreettinen tarkastelu keskittyy kahteen menetelmään: peittämiseen ja kontrolloituun taulukon säätöön, eli CTA:han (engl. controlled tabular adjustment). Peittäminen on 1970-luvulta asti ollut suosittu suojausmenetelmä, mutta sen myötä taulukosta häviää liikaa tietoa. 2000-luvulla kehitetty vaihtoehtoinen menetelmä CTA pyrkii peittämistä paremmin säilyttämään suojattujen taulukoiden tärkeät ominaisuudet, kuten taulukon additiivisuuden ja soluarvojen jakauman. Tutkielman lopussa on lyhyt empiirinen osa, jossa peittämisen ja CTA:n toimivuutta käytännössä testataan todellisen yritysaineiston avulla. Menetelmiä vertailtaessa tultiin tulokseen, että taulukon laadun ja hyödyn säilyttämisen näkökulmasta CTA on peittämistä parempi menetelmä. Koska CTA on uusi menetelmä, sen soveltamiseen liittyy kuitenkin vielä ongelmia. CTA voi johtaa taulukon käyttäjää harhaan, jos käyttäjä ei ymmärrä menetelmän periaatteita.