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Research UpdateGet high now, suffer mental illness laterThree new studies reported in the British Medical Journal offer more evidence that frequent, heavy smoking of marijuana increases susceptibility to depression and schizophrenia. A six-year study of nearly 2,000 adolescents from 44 schools in Victoria, New Zealand, found that girls who used cannabis daily were five times more likely to become depressed and suffer from anxiety. Using cannabis once a week or more doubled the risk. A Swedish study found that those who smoked marijuana more than 50 times by age 18 were 30 per cent more likely to develop schizophrenia later. The 27-year tracking study involved over 50,000 men, aged 18 to 20, conscripted for compulsory military service between 1969 and 1970. The authors concluded that 13 per cent of schizophrenia cases could be prevented by stopping cannabis use. Similarly, a British team found that risk of schizophrenia was highest among teenagers who smoked marijuana. In their study of more than 1,000 New Zealanders in their early twenties, the researchers found that one tenth who smoked marijuana as teens were diagnosed with schizophrenia by age 26. All three studies revealed a dose-dependent pattern between increased use and disease risk, even after ruling out the potential effect of other psychostimulants and pre-existing psychoses. British Medical Journal, November 22, 2002, v. 325: 1212-1213, 1195-1198 and 1199. Unearthing new risk gene for schizophreniaResearchers have uncovered a variation of a gene called Nogo, overexpressed in schizophrenia, which suggests why certain individuals may develop the disease. University of Toronto researchers analyzed DNA samples from blood samples and post-mortem brain tissues from 81 people with schizophrenia and 61 people without schizophrenia. They found that 21 per cent of those with schizophrenia had inherited a variant of the Nogo gene from both parents, while only two of the controls had a copy of the gene variant. Apparently, it takes two copies of the variant, one from each parent, to lead to schizophrenia. The researchers also found that the Nogo gene variant was much more prevalent in cases of adult onset schizophrenia, while those with early onset (before age 20) were much less likely to have the Nogo polymorphism. This is the first research to find a gene that crosses all ethnic groups; other studies have only been able to relate risk genes in specific ethnic populations. However, the new data also means that there is one less factor to distinguish schizophrenia among various populations. The findings suggest that the Nogo variant in schizophrenia may contribute to the abnormal regulation of Nogo gene expression, suggest a role for Nogo in disease-related neurodevelopment problems, and perhaps a role in affective disorders. Molecular Brain Research, November 2002, v. 107(2): 183-189. G. Novak et al., Department of Pharmacology, University of Toronto, Toronto, Ontario. Older drinkers may do better in treatmentOlder individuals with alcohol dependency adhere more to medication and therapy than younger individuals, according to researchers at the University of Pennsylvania. The researchers followed 183 clients being treated for alcohol dependency over a nine-month period. Participants received a placebo for seven to 14 days, then were randomly assigned to nine months of naltrexone (100-mg daily); three months of naltrexone, followed by six months of placebo; or nine months of placebo alone. The published findings focus on the first three months of treatment. The perception to date has been that older clients are less able to or interested in changing their behaviour. Results, however, showed that older participants (average age 62) fared better than younger participants (average age 42) in many treatment aspects: 85 per cent of the older participants versus 64.1 per cent of younger participants were more likely to complete treatment; 80 per cent versus 55 per cent complied with medication; 43 per cent versus 26 per cent abstained from alcohol; and 42.5 per cent versus 64.1 per cent relapsed during the program. The authors suggest that future research should compare age-neutral models with age-specific treatment programs. American Journal of Geriatric Psychiatry, November/December 2002, v. 10(6): 742-749. David W. Oslin et al., Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania. Link between sexual harassment and eating disordersNew research shows a link between sexual harassment and eating disorders among women that is mediated by psychological stress, self-esteem and self-blame. Only one study to date has examined a possible link between sexual harassment and eating disorders that exclusively looked at women. Earlier research found a link between sexual harassment and eating disorder behaviour; however, the definition encompassed harassment by peers in social settings, whereas the current study strictly considered workplace sexual harassment. The current research included three samples drawn from 472 active-duty military women, 254 active-duty military men and 1,853 women involved in a sexual harassment lawsuit against a corporation. Results indicated that psychological distress mediated eating disorder behaviour, since people use eating disorders to help alleviate or numb negative feelings and separate them from traumatic memories. Low self-esteem and self-blame stemming from sexual harassment were found to cause psychological distress, which, in turn, brought on eating disorder behaviour. The authors also found that the link between sexual harassment and eating disorders may be specific to women, as symptoms seemed unrelated in males. However, the authors add that although the association was statistically significant, it was relatively small. Journal of Consulting and Clinical Psychology, 2002, v. 70(5): 1170-1181. Melanie S. Harned and Louise F. Fitzgerald, Department of Psychology, University of Illinois at Urbana-Champaign. Angela Pirisi
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This page was last modified on Tuesday, August 5, 2003 3:47 PM
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