A twin study of cognitive function in chronic fatigue syndrome: The effects of sudden illness onset.

Variable reports of neuropsychological deficits in individuals with chronic fatigue syndrome (CFS) may, in part, be attributable to methodological limitations. In this study, these limitations were addressed by controlling for genetic and environmental influences and by assessing the effects of comorbid depression and mode of illness onset. Specifically, the researchers conducted a co-twin control study of 22 pairs of monozygotic twins, in which 1 twin met strict criteria for CFS and the co-twin was healthy. Twins underwent a structured psychiatric interview and comprehensive neuropsychological assessment evaluating 6 cognitive domains. Results indicated that twin groups had similar intellectual and visual memory functioning, but fatigued twins exhibited decreases in motor functions (p = .05), speed of information processing (p = .02), verbal memory (p = .02), and executive functioning (p = .01). Major depression did not affect neuropsychological functioning among fatigued twins, although twins with sudden illness onset demonstrated slowed information processing compared with those with gradual onset (p = .01). Sudden onset CFS was associated with reduced speed of information processing. If confirmed, these findings suggest the need to distinguish illness onset in future CFS studies and may have implications for treatment, cognitive rehabilitation, and disability determination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Smokeless Tobacco Use and Its Relation to Panic Disorder, Major Depression, and Posttraumatic Stress Disorder in American Indians

INTRODUCTION: Rates of nicotine use are high in American Indians. Anxiety and depression tend to be associated with cigarette use, but the association of anxiety and depression with smokeless tobacco (ST) is less clear. We asked if panic disorder, major depression, and posttraumatic stress disorder (PTSD) are related to lifetime ST use in 2 American Indian tribes. METHODS: Logistic regression analyses examined the association between lifetime panic disorder, major depression, and PTSD and the odds of lifetime ST use status after controlling for sociodemographic characteristics, smoking status, and alcohol use disorders in 1,506 Northern Plains and 1,268 Southwest tribal members. RESULTS: Odds of lifetime ST use was 1.6 times higher in Northern Plains tribal members with a lifetime history of PTSD after controlling for sociodemographic variables and smoking (95% CI: 1.1, 2.3; p = .01). This association remained significant after further adjustment for panic disorder and major depression (odds ratio [OR] = 1.5; 95% CI: 1.0, 2.2; p = .04) but was diminished after accounting for alcohol use (OR = 1.3; 95% CI: 0.9, 1.9; p = .23). In the Southwest, lifetime psychiatric disorders were not associated with lifetime ST use status. Increasing psychiatric comorbidity was significantly linked to increased odds of ST use in both tribes. Conclusions: This study is the first to examine psychiatric conditions and lifetime ST use in a large, geographically diverse American Indian community sample. Although approximately 30% of tribal members were lifetime users of ST, the association with lifetime psychiatric disorders was not as strong as those observed with cigarette smoking. Understanding shared mechanisms between all forms of tobacco use with anxiety and depressive disorders remains an important area for investigation.     

Cognitive Processing in Monozygotic Twins Discordant for Chronic Fatigue Syndrome.

Twenty-one pairs of monozygotic twins discordant for chronic fatigue syndrome (CFS) and 21 matched healthy control (HC) subjects were assessed with 5 untimed tests and 5 timed tests from the computer-based NeuroCognitive Assessment Battery (R. K. Mahurin, 1993). Random effects regression showed no difference between CFS and healthy twins on any of the cognitive tests. Further, the twin groups did not differ from the HC group on any content-dependent measure. In contrast, both sets of twins performed worse than the HC group on all speed-dependent tests except Finger Tapping. Self-rated fatigue and dysphoric mood were only weakly correlated with cognitive performance. These data point toward a shared genetic trait related to information processing that is manifest in the CFS context. The findings have implications for differentiating genetic and acquired vulnerability in the symptomatic expression of the disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)