Addictions and their familiality in Iceland

SAA Treatment Center, Reykjavik, Iceland.
Annals of the New York Academy of Sciences (Impact Factor: 4.38). 02/2010; 1187(1):208-17. DOI: 10.1111/j.1749-6632.2009.05151.x
Source: PubMed


Here, we provide an overview of previous family studies of addiction and present a new family study based on clinical data for more than 19,000 individuals who have been treated for addiction in Iceland over the last three decades. Coupled with the extensive Icelandic genealogy information, this population-based sample provides a unique opportunity for family studies. The relative risk (RR) was determined for up to fifth-degree relatives of probands diagnosed with alcohol, cannabis, sedative, and amphetamine dependence. We observe highly significant RR values for all substances ranging from 2.27 for alcohol to 7.3 for amphetamine, for first-degree relatives, and RRs significantly above 1 for distant relations, where the effect of shared environmental factors is minimized. The magnitude of risk in psychostimulant dependence is particularly striking. These findings emphasize the role of genetics in the etiology of addiction and highlight the importance of substance-specific effects.

Download full-text


Available from: Daníel Fannar Guðbjartsson,
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Amphetamine-type substances are the second most widely used illicit drugs in the United States. There is evidence to suggest that stimulant use (cocaine and methamphetamine) has a heritable component, yet the areas of the genome underlying these use disorders are yet to be identified. This study's aims were to map loci linked to stimulant dependence, heavy use, and craving in an American Indian community at high risk for substance dependence. DSM diagnosis of stimulant dependence, as well as indices of stimulant "craving," and "heavy use," were obtained using the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA). Genotypes were determined for a panel of 791 microsatellite polymorphisms in 381 members of multiplex families using SOLAR. Stimulant dependence, stimulant "craving," and "heavy stimulant use," were all found to be heritable. Analyses of multipoint variance component LOD scores, failed to yield evidence of linkage for stimulant dependence. For the stimulant "craving" phenotype, linkage analysis revealed a locus that had a LOD score of 3.02 on chromosome 15q25.3-26.1 near the nicotinic receptor gene cluster. A LOD score of 2.05 was found at this same site for "heavy stimulant use." Additional loci with LOD scores above 2.00 were found for stimulant "craving" on chromosomes 12p13.33-13.32 and 18q22.3. These results corroborate the importance of "craving" as an important phenotype that is associated with regions on chromosome 12, 15, and 18, that have been highlighted in prior segregation studies in this and other populations for substance dependence-related phenotypes.
    American Journal of Medical Genetics Part B Neuropsychiatric Genetics 12/2011; 156B(7):772-80. DOI:10.1002/ajmg.b.31218 · 3.42 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective Not everyone who takes drugs becomes addicted, but the likelihood of developing drug addiction is greater in people with a family history of drug or alcohol dependence. Relatively little is known about how genetic risk mediates the development of drug dependence. By comparing the phenotypic profile of individuals with and without a family history of addiction, the authors sought to clarify the extent to which cognitive dysfunction and personality traits are shared by family members—and therefore likely to have predated drug dependence—and which aspects are specific to drug-dependent individuals. Method The authors assessed cognitive function and personality traits associated with drug dependence in stimulant-dependent individuals (N=50), their biological siblings without a history of drug dependence (N=50), and unrelated healthy volunteers (N=50). Results Cognitive function was significantly impaired in the stimulant-dependent individuals across a range of domains. Deficits in executive function and response control were identified in both the stimulant-dependent individuals and in their non-drug-dependent siblings. Drug-dependent individuals and their siblings also exhibited elevated anxious-impulsive personality traits relative to healthy comparison volunteers. Conclusions Deficits in executive function and response regulation as well as anxious-impulsive personality traits may represent endophenotypes associated with the risk of developing cocaine or amphetamine dependence. The identification of addiction endophenotypes may be useful in facilitating the rational development of therapeutic and preventive strategies.
    American Journal of Psychiatry 09/2012; 169(9):926-36. DOI:10.1176/appi.ajp.2012.11091421 · 12.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The self-medication hypothesis emphasizes the role of distressing affect as the primary motivator for the compulsive use that leads to substance dependence. The model also postulates that there will be psychopharmacological specificity between symptom presentation and the primary drug of dependence. In this review, the self-medication hypothesis is examined in relation to the development and chronicity of heroin dependence. It is argued that if self-medication has a role in engendering and extending substance dependence, it should be apparent in the use of a drug that carries such overwhelming personal risk. The psychopathology seen among adult users is certainly consistent with the model. More importantly, however, are the extraordinarily high levels of childhood trauma and psychopathology that occur typically well before the initiation of heroin use. In contrast, the postulate of drug specificity appears less supported by the polydrug use patterns typical of heroin users, and does not appear to be a necessary corollary of the model.
    Addiction 10/2012; 108(4). DOI:10.1111/j.1360-0443.2012.04001.x · 4.74 Impact Factor
Show more