A variant associated with nicotine dependence, lung cancer and peripheral arterial disease.

Smoking is a leading cause of preventable death, causing about 5 million premature deaths worldwide each year. Evidence for genetic influence on smoking behaviour and nicotine dependence (ND) has prompted a search for susceptibility genes. Furthermore, assessing the impact of sequence variants on smoking-related diseases is important to public health. Smoking is the major risk factor for lung cancer (LC) and is one of the main risk factors for peripheral arterial disease (PAD). Here we identify a common variant in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24 with an effect on smoking quantity, ND and the risk of two smoking-related diseases in populations of European descent. The variant has an effect on the number of cigarettes smoked per day in our sample of smokers. The same variant was associated with ND in a previous genome-wide association study that used low-quantity smokers as controls, and with a similar approach we observe a highly significant association with ND. A comparison of cases of LC and PAD with population controls each showed that the variant confers risk of LC and PAD. The findings provide a case study of a gene-environment interaction, highlighting the role of nicotine addiction in the pathology of other serious diseases.

[The prevalence of personality disorders in the greater-Reykjavik area]. / Tíoni persónuleikaraskana á Stór-Reykjavíkursvaeoinu.

The prevalence of personality disorders was estimated in a sample of 805 individuals randomly selected from the greater Reykjavik area. The sample consisted of 3 equally large cohorts of persons born in 1931, 1951 and 1971. The individuals were asked to participate in a survey of mental health. Of those contacted, 52% of the total group participated. The instrument used for estimating personality disorders was the DIP-Q. The results show that the overall percentage with any disorder was 11 % according to DSM-IV and 12 % according to ICD-10. The most frequent disorder of the whole group, according to DSM-IV criteria, was obsessive-compulsive personality disorder (7.3 %) and schizotypal personality disorder according to ICD-10 criteria, which was to be found in 9% of the group. Other disorders were less frequently found. Comorbidity was high among those with a personality disorder. Of those with disorders according to DSM-IV, 67% had more than one disorder. Similarly, according to the ICD criteria, comorbidity was to be found in 80% of the sample. Among women, anxious/avoidant personality disorder was the most common, with the highest sub-group prevalence found among those born in 1971. Similarly, among the men, schizotypal personality disorder was the most common, and most commonly found in the 1971 age group.

[The prevalence of mental disorders in the Greater-Reykjavik area]. / Algengi gedraskana á Stór-Reykjavíkursvaedinu.

The purpose of this study was to estimate the prevalence of mental disorders in a random sample of three age groups born in 1931, 1951 and 1971 and living in the Greater- Reykjavik Area. From the original sample of 300 in each birth cohort 805 were contacted and asked to take part in a survey of mental health. Of those 52% participated. The instrument used for diagnosing mental disorders was the CIDI-Auto. The lifetime prevalence of any ICD-10 disorder was found to be 49.8%. The most frequent diagnoses were mental and behavioral disorders due to use of tobacco (23,6%), somatoform disorders (19.0%) and mental and behavioral disorders due to use of acohol (10.8%).Any anxiety disorder was found in 14.4% and any mood disorder in 13.0%. The one-year prevalence for any disorder was 19.7%, for tobacco use disorder 6.5%, alcohol use disorder 6%, somatoform disorders 10.3%, anxiety disorders 5.5% and mood disorders 2.6%. Alcohol use disorders are more prevalent among men but somatoform disorders, anxiety disorders and mood disorders among women. The prevalence rates of mental disorders found in this study is the same or lower than rates found in other comparable studies. There is no indication of an increase in the rate of mental disorder in Iceland.

The prevalence of chronic fatigue syndrome in Iceland - a national comparison by gender drawing on four different criteria.

The study was carried out to estimate the prevalence of chronic fatigue syndrome (CFS) in Iceland. No previous prevalence studies known to us have been undertaken in Iceland or in Scandinavia. A 95-item custom-made questionnaire was sent to 4000 randomly selected people. The response rate was 63%. The questionnaire was constructed to include questions on all the items found in the four most common criteria for diagnosing CFS; the criteria being Australian, British and American. Results show very different prevalences according to the criteria used. The prevalence ranged from 0 to 4.9%, with the most established criteria yielding a prevalence of 1.4%. Re-test validity of the questionnaire was good, the following results are based on the selection criteria by Fukuda et al. (Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A, et al. The chronic fatigue syndrome: a comprehensive approach to its definition and study. Ann Int Med 1994;121:953-9). Women were in a majority (78%); their mean age was 44, they were fully employed and worked long hours. They believed that the onset of their symptoms was stress related. The type of work was unskilled in the majority of cases. A significant proportion of the males felt a constant buzzing in their ears (P < 0.05). Food suppliants were used daily by significantly more women than men (P < 0.01). Men had more frequently phobic symptoms (P < 0.001) than did women. Differences were found in the prevalence of phobia and panic (P < 0.001) between women in the CFS group compared to healthy ones. A positive correlation was found in the prevalence of phobia between women in the CFS group and those with Iceland Disease.

Seasonal affective disorders: relevance of Icelandic and Icelandic-Canadian evidence to etiologic hypotheses.

OBJECTIVE: This study tests the suggestion of earlier studies concerning the importance of genetic factors in the etiology of winter seasonal affective disorders (SADs) and subsyndromal winter SAD (S-SAD). METHOD: Two study populations of Winnipeg, Manitoba residents were canvassed: 250 adults of wholly Icelandic descent and 1000 adults of non-Icelandic descent. We distributed the Seasonal Pattern Assessment Questionnaire by mail to these 2 populations, yielding 204 and 449 valid responses, respectively. RESULTS: Rates of SAD and S-SAD proved markedly lower in the Icelandic population than those in the non-Icelandic population. CONCLUSIONS: These differences seem unexplained by differences in ambient light or climate, thus indicating that genetic factors contribute to the expression of SADs. Compared with earlier findings from a group of adults of wholly Icelandic descent living in nearby rural Manitoba, the etiologic importance of as-yet-undetermined environmental factors unrelated to latitude or ambient light is also indicated.

Anxiety with panic disorder linked to chromosome 9q in Iceland.

The results of a genomewide scan for genes conferring susceptibility to anxiety disorders in the Icelandic population are described. The aim of the study was to locate genes that predispose to anxiety by utilizing the extensive genealogical records and the relative homogeneity of the Icelandic population. Participants were recruited in two stages: (1) Initial case-identification by a population screening for anxiety disorders, using the Stamm Screening Questionnaire, was followed by aggregation into extended families, with the help of our genealogy database; and (2) those who fulfilled the diagnostic and family aggregation criteria underwent a more detailed diagnostic workup based on the Composite International Diagnostic Interview. Screening for anxiety in close relatives also identified additional affected members within the families. After genotyping was performed with 976 microsatellite markers, affected-only linkage analysis was done, and allele-sharing LOD scores were calculated using the program Allegro. Linkage analysis of 25 extended families, in each of which at least one affected individual had panic disorder (PD), resulted in a LOD score of 4.18 at D9S271, on chromosome 9q31. The intermarker distance was 4.4 cM on average, whereas it was 1.5 cM in the linked region as additional markers were added to increase the information content. The linkage results may be relevant not only to PD but also to anxiety in general, since our linkage study included patients with other forms of anxiety.