Exploring the relationship between genetic and environmental influences on initiation and progression of substance use

AIMS: To examine the genetic and environmental contributions to the initiation of use and progression to more serious use of alcohol, cigarettes and marijuana during adolescence, and to examine the relationship between initiation and progression of substance use. DESIGN: The study used a twin-based design and a new theoretical model, the causal-common-contingent (CCC) model. This allows modelling of the relationship between initiation of use and progression to heavier use as a two-stage model and the examination of genetic and environmental influences on both stages, while taking into account their relationship. PARTICIPANTS: The participants consisted of 1214 twin pairs (69% response rate) aged 11-19 years sampled from the UK population-based Cardiff Study of All Wales and North-west of England Twins (CaStANET). MEASUREMENTS: Data on adolescent initiation and progression to more serious use of alcohol, cigarettes and marijuana were obtained using self-report questionnaires. FINDINGS: Initiation of alcohol and progression to heavier alcohol use had separate but related underlying aetiologies. For cigarette and marijuana use the relation between initiation and progression to heavier use was stronger, suggesting greater overlap in aetiologies. For all three substances, environmental influences that make twins more similar (common environment) tended to be greater for initiation, while genetic influences were stronger for heavier use. CONCLUSIONS: These findings have implications for policy decisions aimed at an adolescent and early adult age group. Specifically, these findings suggest that it may be more efficacious to focus alcohol interventions on risk factors for the development of heavier use rather than initiation of use. In contrast, interventions aimed at reducing the initiation of cigarettes and marijuana use may be more appropriate

Screening for glucose intolerance and development of a lifestyle education programme for prevention of Type 2 diabetes in a population with intellectual disabilities

Background: The prevalence of type 2 diabetes mellitus (T2DM) and of cardiovascular disease (CVD) is believed to be higher among people with intellectual disability (ID) than in the general population. However, research on prevalence and prevention in this population is limited. Objectives: The objectives of this programme of work were to establish a programme of research that would significantly enhance the knowledge and understanding of impaired glucose regulation (IGR) and T2DM in people with ID; to test strategies for the early identification of IGR and T2DM in people with ID; and to develop a lifestyle education programme and educator training protocol to promote behaviour change in a population with ID and IGR (or at a high risk of T2DM/CVD). Setting: Leicestershire, UK. Participants: Adults with ID were recruited from community settings, including residential homes and family homes. Adults with mild to moderate ID who had an elevated body mass index (BMI) of ≥ 25 kg/m2 and/or IGR were invited to take part in the education programme. Main outcome measures: The primary outcome of the screening programme was the prevalence of screen-detected T2DM and IGR. The uptake, feasibility and acceptability of the intervention were assessed. Data sources: Participants were recruited from general practices, specialist ID services and clinics, and through direct contact. Results: A total of 930 people with ID were recruited to the screening programme: 58% were male, 80% were white and 68% were overweight or obese. The mean age of participants was 43.3 years (standard deviation 14.2 years). Bloods were obtained for 675 participants (73%). The prevalence of previously undiagnosed T2DM was 1.3% [95% confidence interval (CI) 0.5% to 2%] and of IGR was 5% (95% CI 4% to 7%). Abnormal IGR was more common in those of non-white ethnicity; those with a first-degree family history of diabetes; those with increasing weight, waist circumference, BMI, diastolic blood pressure or triglycerides; and those with lower high-density lipoprotein cholesterol. We developed a lifestyle educational programme for people with ID, informed by findings from qualitative stakeholder interviews (health-care professionals, n = 14; people with ID, n = 7) and evidence reviews. Subsequently, 11 people with ID (and carers) participated in pilot education sessions (two groups) and five people attended education for the feasibility stage (one group). We found that it was feasible to collect primary outcome measures on physical activity and sedentary behaviour using wrist-worn accelerometers. We found that the programme was relatively costly, meaning that large changes in activity or diet (or a reduction in programme costs) would be necessary for the programme to be cost-effective. We also developed a quality development process for assessing intervention fidelity. Limitations: We were able to screen only around 30% of the population and involved only a small number in the piloting and feasibility work. Conclusions: The results from this programme of work have significantly enhanced the existing knowledge and understanding of T2DM and IGR in people with ID. We have developed a lifestyle education programme and educator training protocol to promote behaviour change in this population. Future work: Further work is needed to evaluate the STOP Diabetes intervention to identify cost-effective strategies for its implementation

Genetic and environmental influences on the relationship between peer alcohol use and own alcohol use in adolescents

Aims: Genetically influenced aspects of adolescent behaviour can play a role in alcohol use and peer affiliation. We explored the correlations between friends' alcohol use and adolescent own use with a genetically sensitive design. Design: Genetic and environmental factors were estimated on adolescent reports of their friends' alcohol use and their own use and problem use of alcohol. The correlations between the genetic and environmental factors that influence friends' alcohol use and adolescent own alcohol use and problem use were also estimated. Participants: A total of 862 twin pairs aged 11-17 years sampled from the UK population-based Cardiff Study of All Wales and North-west of England Twins (CaStANET). Measurements: Data on adolescent own alcohol use and problem use and the alcohol use of their three best friends were obtained using self-report questionnaires. Findings: A significant genetic influence was found on adolescent friends' alcohol use (about 30%). Significant correlations of 0.60 and 0.70 were found between the genetic influences on friends' alcohol use and adolescents' own use and problem use of alcohol. Common environmental influences were almost completely correlated for friends' alcohol use and adolescents' own alcohol use and problem use (0.91 and 0.94). Conclusions: There is considerable overlap in the common environmental and genetic factors that contribute to the relationship between adolescents' own alcohol use and that of their friends. These findings contribute to understanding of the mechanisms by which friends' alcohol use influences adolescent drinking behaviour. © 2007 The Authors

The Moderating Role of Close Friends in the Relationship Between Conduct Problems and Adolescent Substance Use

Purpose Conductproblems and peer effects are among the strongest risk factors for adolescentsubstance use and problem use. However, it is unclear to what extent the effects of conductproblems and peer behavior interact, and whether adolescents' capacity to refuse the offer of substances may moderate such links. This study was conducted to examine relationships between conductproblems, closefriends' substance use, and refusal assertiveness with adolescents' alcohol use problems, tobacco, and marijuana use. Methods We studied a population-based sample of 1,237 individuals from the Cardiff Study of All Wales and North West of England Twins aged 11–18 years. Adolescent and mother-reported information was obtained. Statistical analyses included cross-sectional and prospective logistic regression models and family-based permutations. Results Conductproblems and closefriends' substance use were associated with increased adolescents' substance use, whereas refusal assertiveness was associated with lower use of cigarettes, alcohol, and marijuana. Peer substance use moderated the relationship between conductproblems and alcohol use problems, such that conductproblems were only related to increased risk for alcohol use problems in the presence of substance-using friends. This effect was found in both cross-sectional and prospective analyses and confirmed using the permutation approach. Conclusions Reduced opportunities for interaction with alcohol-using peers may lower the risk of alcohol use problems in adolescents with conductproblems

A systematic review of the relationships between family functioning, pubertal timing and adolescent substance use

Aims Experiences linked to poor family functioning and pubertal timing have each been associated with increased risk of substance misuse in adolescence. However, it remains unclear to what extent family functioning and pubertal timing combine to put adolescents at particular risk. Method A systematic review was planned, undertaken and reported according to the 27 items of the PRISMA statement. Databases World of Knowledge, PsycINFO and PubMed were searched. Fifty-eight papers were retained and are discussed in this review after screening titles, abstracts and full papers against pre-established exclusion criteria. Results The combination of off-time pubertal timing and poor parent–adolescent relationship quality has been related to higher levels of substance use. However, this is an under-studied area of research and the evidence is less strong for boys than girls. Conclusions Adolescents experiencing both poor parent–adolescent relationship quality and off-time pubertal timing may represent a high-risk group that can benefit from approaches aimed at reducing risk of substance misuse

Housing improvements for health and associated socio-economic outcomes.

BACKGROUND: The well established links between poor housing and poor health indicate that housing improvement may be an important mechanism through which public investment can lead to health improvement. Intervention studies which have assessed the health impacts of housing improvements are an important data resource to test assumptions about the potential for health improvement. Evaluations may not detect long term health impacts due to limited follow-up periods. Impacts on socio-economic determinants of health may be a valuable proxy indication of the potential for longer term health impacts. OBJECTIVES: To assess the health and social impacts on residents following improvements to the physical fabric of housing. SEARCH METHODS: Twenty seven academic and grey literature bibliographic databases were searched for housing intervention studies from 1887 to July 2012 (ASSIA; Avery Index; CAB Abstracts; The Campbell Library; CINAHL; The Cochrane Library; COPAC; DH-DATA: Health Admin; EMBASE; Geobase; Global Health; IBSS; ICONDA; MEDLINE; MEDLINE In-Process & Other Non-Indexed Citations; NTIS; PAIS; PLANEX; PsycINFO; RIBA; SCIE; Sociological Abstracts; Social Science Citations Index; Science Citations Index expanded; SIGLE; SPECTR). Twelve Scandinavian grey literature and policy databases (Libris; SveMed+; Libris uppsök; DIVA; Artikelsök; NORART; DEFF; AKF; DSI; SBI; Statens Institut for Folkesundhed; Social.dk) and 23 relevant websites were searched. In addition, a request to topic experts was issued for details of relevant studies. Searches were not restricted by language or publication status. SELECTION CRITERIA: Studies which assessed change in any health outcome following housing improvement were included. This included experimental studies and uncontrolled studies. Cross-sectional studies were excluded as correlations are not able to shed light on changes in outcomes. Studies reporting only socio-economic outcomes or indirect measures of health, such as health service use, were excluded. All housing improvements which involved a physical improvement to the fabric of the house were included. Excluded interventions were improvements to mobile homes; modifications for mobility or medical reasons; air quality; lead removal; radon exposure reduction; allergen reduction or removal; and furniture or equipment. Where an improvement included one of these in addition to an included intervention the study was included in the review. Studies were not excluded on the basis of date, location, or language. DATA COLLECTION AND ANALYSIS: Studies were independently screened and critically appraised by two review authors. Study quality was assessed using the risk of bias tool and the Hamilton tool to accommodate non-experimental and uncontrolled studies. Health and socio-economic impact data were extracted by one review author and checked by a second review author. Studies were grouped according to broad intervention categories, date, and context before synthesis. Where possible, standardized effect estimates were calculated and statistically pooled. Where meta-analysis was not appropriate the data were tabulated and synthesized narratively following a cross-study examination of reported impacts and study characteristics. Qualitative data were summarized using a logic model to map reported impacts and links to health impacts; quantitative data were incorporated into the model. MAIN RESULTS: Thirty-nine studies which reported quantitative or qualitative data, or both, were included in the review. Thirty-three quantitative studies were identified. This included five randomised controlled trials (RCTs) and 10 non-experimental studies of warmth improvements, 12 non-experimental studies of rehousing or retrofitting, three non-experimental studies of provision of basic improvements in low or mIddle Income countries (LMIC), and three non-experimental historical studies of rehousing from slums. Fourteen quantitative studies (42.4%) were assessed to be poor quality and were not included in the synthesis. Twelve studies reporting qualitative data were identified. These were studies of warmth improvements (n = 7) and rehousing (n = 5). Three qualitative studies were excluded from the synthesis due to lack of clarity of methods. Six of the included qualitative studies also reported quantitative data which was included in the review.Very little quantitative synthesis was possible as the data were not amenable to meta-analysis. This was largely due to extreme heterogeneity both methodologically as well as because of variations in the intervention, samples, context, and outcome; these variations remained even following grouping of interventions and outcomes. In addition, few studies reported data that were amenable to calculation of standardized effect sizes. The data were synthesised narratively.Data from studies of warmth and energy efficiency interventions suggested that improvements in general health, respiratory health, and mental health are possible. Studies which targeted those with inadequate warmth and existing chronic respiratory disease were most likely to report health improvement. Impacts following housing-led neighbourhood renewal were less clear; these interventions targeted areas rather than individual households in most need. Two poorer quality LMIC studies reported unclear or small health improvements. One better quality study of rehousing from slums (pre-1960) reported some improvement in mental health. There were few reports of adverse health impacts following housing improvement. A small number of studies gathered data on social and socio-economic impacts associated with housing improvement. Warmth improvements were associated with increased usable space, increased privacy, and improved social relationships; absences from work or school due to illness were also reduced.Very few studies reported differential impacts relevant to equity issues, and what data were reported were not amenable to synthesis. AUTHORS' CONCLUSIONS: Housing investment which improves thermal comfort in the home can lead to health improvements, especially where the improvements are targeted at those with inadequate warmth and those with chronic respiratory disease. The health impacts of programmes which deliver improvements across areas and do not target according to levels of individual need were less clear, but reported impacts at an area level may conceal health improvements for those with the greatest potential to benefit. Best available evidence indicates that housing which is an appropriate size for the householders and is affordable to heat is linked to improved health and may promote improved social relationships within and beyond the household. In addition, there is some suggestion that provision of adequate, affordable warmth may reduce absences from school or work.While many of the interventions were targeted at low income groups, a near absence of reporting differential impacts prevented analysis of the potential for housing improvement to impact on social and economic inequalities

Genetic and non-genetic influences on the development of co-occurring alcohol problem use and internalizing symptomatology in adolescence: a review

Aims. Alcohol problem use during adolescence has been linked to a variety of adverse consequences, including cigarette and illicit drug use, delinquency, adverse effects on pubertal brain development and increased risk of morbidity and mortality. In addition, heavy alcohol-drinking adolescents are at increased risk of comorbid psychopathology, including internalizing symptomatology (especially depression and anxiety). A range of genetic and non-genetic factors have been implicated in both alcohol problem use as well as internalizing symptomatology. However, to what extent shared risk factors contribute to their comorbidity in adolescence is poorly understood. Design. We conducted a systematic review on Medline, PsycINFO, Embase and Web of Science to identify epidemiological and molecular genetic studies published between November 1997 and November 2007 that examined risk factors that may be shared in common between alcohol problem use and internalizing symptomatology in adolescence. Findings. Externalizing disorders, family alcohol problems and stress, as well as the serotonin transporter (5-HTT) S-allele, the monoamine oxidase A (MAOA) low-activity alleles and the dopamine D2 receptor (DDR2) Taq A1 allele have been associated most frequently with both traits. An increasing number of papers are focusing upon the role of gene–gene (epistasis) and gene–environment interactions in the development of comorbid alcohol problem use and internalizing symptomatology. Conclusions. Further research in adolescents is warranted; the increasing availability of large longitudinal genetically informative studies will provide the evidence base from which effective prevention and intervention strategies for comorbid alcohol problems and internalizing symptomatology can be developed

Genetic and non-genetic influences on the development of co-occurring alcohol problem use and internalizing symptomatology in adolescence: a review

Aims. Alcohol problem use during adolescence has been linked to a variety of adverse consequences, including cigarette and illicit drug use, delinquency, adverse effects on pubertal brain development and increased risk of morbidity and mortality. In addition, heavy alcohol-drinking adolescents are at increased risk of comorbid psychopathology, including internalizing symptomatology (especially depression and anxiety). A range of genetic and non-genetic factors have been implicated in both alcohol problem use as well as internalizing symptomatology. However, to what extent shared risk factors contribute to their comorbidity in adolescence is poorly understood. Design. We conducted a systematic review on Medline, PsycINFO, Embase and Web of Science to identify epidemiological and molecular genetic studies published between November 1997 and November 2007 that examined risk factors that may be shared in common between alcohol problem use and internalizing symptomatology in adolescence. Findings. Externalizing disorders, family alcohol problems and stress, as well as the serotonin transporter (5-HTT) S-allele, the monoamine oxidase A (MAOA) low-activity alleles and the dopamine D2 receptor (DDR2) Taq A1 allele have been associated most frequently with both traits. An increasing number of papers are focusing upon the role of gene–gene (epistasis) and gene–environment interactions in the development of comorbid alcohol problem use and internalizing symptomatology. Conclusions. Further research in adolescents is warranted; the increasing availability of large longitudinal genetically informative studies will provide the evidence base from which effective prevention and intervention strategies for comorbid alcohol problems and internalizing symptomatology can be developed