Lisa M. Jack

Association of midlife blood pressure to late-life cognitive decline and brain morphology

Objective: To investigate the association between midlife systolic blood pressure (SBP) and late-life cognitive decline and brain morphology in a sample of community-dwelling elderly men 68 to 79 years of age. Methods: Subjects are surviving members from the prospective National Heart, Lung, and Blood Institute Twin Study (intake, 1969 to 1972) who, when examined for a fourth time in 1995 through 1997, underwent brain MRI and repeated assessment of neurobehavioral functioning. Quantification of the MR images determined cerebral volume and total volume of white matter hyperintensities (WMHIs) for 392 subjects. Midlife SBP levels measured in 1970, 1980, and 1985 were used to classify subjects into low, medium, and high midlife SBP categories. A 10-year change in performance on the Mini-Mental State Examination, Digit Symbol Substitution Test, Benton Visual Retention Test, and Verbal Fluency Test was also calculated for these subjects. For all reported analyses, patients were treated as genetically unrelated individuals. Results: Subjects with high midlife SBP experienced a greater decline in cognitive performance and had larger WMHI volumes at follow-up in late life than did those with low midlife SBP. Decreased brain parenchyma and increased WMHI volumes were associated with decline in neurobehavioral functioning as measured in late life independent of age, education, and baseline levels of cognition. Conclusions: Midlife SBP is a significant predictor of both decline in cognitive function and MR volumetric measures of brain atrophy in late life. Because decline in neurobehavioral functioning was associated with decreased brain volume and increased WMHI volume, we conclude that the long-term impact of elevated SBP on decline in late-life neurobehavioral functioning is likely to be mediated through its chronic, negative effect on structural characteristics of the brain.

Evidence For Genetic Variance in White Matter Hyperintensity Volume in Normal Elderly Male Twins

BACKGROUND AND PURPOSE White matter hyperintensities (WMHs), as detected by MRI, are common among the elderly and are frequently interpreted as representing a subclinical form of ischemic brain damage. We used volumetric MR techniques to investigate the contribution of genes and the environment to measures of brain morphology in a sample of community dwelling elderly male twins. METHODS Brain MR (1.5 T) scans were obtained from 74 monozygotic (MZ) and 71 dizygotic (DZ), white, male, World War II veteran twins born in the United States and age 68 to 79 when scanned. MR quantification used a previously published semiautomated segmentation algorithm to segment brain images into total brain, cerebrospinal fluid (CSF), and WMH volumes. Twin pair covariances were computed for each measure, and structural equation genetic models were fitted to these data. RESULTS Total cranial, brain parenchyma, CSF, and WMH volumes were highly correlated in MZ pairs, and correlations in MZ pairs were significantly greater than those in DZ pairs. Structural equation modeling indicated heritabilities of 91%, 92%, and 73%, respectively, for total cranial, brain parenchyma, and WMH volumes. Correction for age and head size reduced the heritability of brain parenchyma to 62% (95% confidence interval, 56% to 68%) and the heritability of WMH volume to 71% (95% confidence interval, 66% to 76%). Proband concordance rates for large amounts of WMH were 61% in MZ pairs and 38% in DZ pairs, compared with a prevalence of 15% in the entire sample. CONCLUSIONS This study is the first to quantify the relative contribution of genetic and individual environmental influences to measures of brain morphology in the elderly.

Predictors of Brain Morphology for the Men of the NHLBI Twin Study

BACKGROUND AND PURPOSE Cross-sectional studies show that cerebrovascular risk factors are associated with increased brain atrophy, accumulation of abnormal cerebral white matter signals, and clinically silent stroke. We extend these findings by examining the relationship between midlife cerebrovascular risk factors and later-life differences in brain atrophy, amount of abnormal white matter, and stroke on MRI. METHODS Subjects were the 414 surviving members of the prospective National Heart, Lung, and Blood Institute Twin Study, who have been examined on 4 separate occasions, spanning the 25 years between 1969-1973 and 1995-1997. Quantitative measures of brain volume, volume of abnormal white matter signal (WMHI), and volume of stroke, when present, were obtained from those participating in the fourth examination. RESULTS The mean+/-SD age of the subjects was 47.2+/-3.0 years at initial examination and 72. 5+/-2.9 years at final examination. Average blood pressure (BP) levels were normal, although 32% of the subjects had received or were currently taking antihypertensive medications. As a group, 31% had symptomatic cardiovascular disease, 11% had symptomatic cerebrovascular disease, and 8% had symptomatic peripheral vascular disease. Both systolic and diastolic BP levels at initial examination were inversely related to brain volume and positively related to WMHI volume. Multiple regression analysis identified BP-related measures and vascular risk factors as significant predictors of brain and WMHI volumes. In addition, the magnitude of orthostatic BP change was significantly associated with WMHI volume. Subjects with extensive amounts of WMHI had significantly higher systolic BP at the final examination and a higher prevalence of symptomatic cardiovascular and cerebrovascular disease, without significant differences in the prevalence of hypertension treatment. CONCLUSIONS Midlife BP measures are significantly associated with later-life brain and WMHI volumes and the prevalence of symptomatic vascular disease. Since WMHI share cerebrovascular risk factors and extensive WMHI are associated with symptomatic vascular disease, extensive WMHI may be a subclinical expression of cerebrovascular disease. Careful treatment of midlife BP elevations may diminish these later-life brain changes.

Abstinence effects as predictors of 28-day relapse in smokers

The present analysis sought to determine the relationship between abstinence effects in 64 ex-smokers (mean age = 41.1 years) and the rate at which they relapsed over 4 weeks of biochemically confirmed follow-up. This analysis focused on six abstinence effects that play a central role in the DSM-III-R and DSM IV definitions of withdrawal from nicotine: anger, depression, craving, appetite, confusion, and tension. Significant increases were observed for all six symptoms following cessation, and, with the exception of craving, substantial intercorrelations among the abstinence effects were noted. Cox proportional hazards survival models identified increases in anger, depressed mood, and craving to be significantly associated with a shorter time to relapse (all p < .03). Stepwise Cox proportional hazards survival analysis identified increases in depressed mood and craving as the most significant combination of abstinence effects in relation to time to relapse. A more stringent test of the potency of the relationship between these abstinence effects and time to relapse was conducted in which two other risk factors in this sample, method of quitting and education level, were also included in the model testing sequence. Even after adjustment for these significant risk factors, the increase in craving remained a significant predictor of a higher rate of relapse. This result suggests a robustness to this particular abstinence effect as a determinant of the speed with which ex-smokers relapse over a 1-month interval after cessation.

Dopamine receptor DRD2 genotype and smoking cessation outcome following treatment with bupropion SR

The A1 allele of the dopamine D2 receptor gene (DRD2) is associated with a reduced number of dopamine binding sites in the brain and with the increased likelihood of substance abuse and addictive behavior. In a study of smokers enrolled in an open-label, randomized effectiveness trial, we investigated whether variants in the DRD2 receptor gene are associated with smoking cessation outcomes following treatment with a combination of bupropion SR and behavioral counseling. Adherence to treatment and point-prevalent smoking status were assessed at 3 and 12 months, respectively, following a target quit date. Compared to women who carry both A2 alleles, women with at least one A1 allele were more likely to report having stopped taking bupropion due to medication side effects (odds ratio (OR)=1.91, 95% confidence interval (CI)=1.01–3.60; P<0.04) and at 12 months were somewhat more likely to report smoking (OR=0.76, 95% CI=0.56–1.03; P<0.076). Significant associations or trends were not observed in men. In women, individual variability in responsiveness to bupropion-based treatment may be partially due to differences in genetic variants influencing dopamine receptor function.

Asthma Discordance in Twins Is Linked to Epigenetic Modifications of T Cells

T cells mediate the inflammatory responses observed in asthma among genetically susceptible individuals and have been suspected to be prone to epigenetic regulation. However, these relationships are not well established from past clinical studies that have had limited capacity to control for the effects of variable genetic predisposition and early environmental exposures. Relying on a cohort of monozygotic twins discordant for asthma we sought to determine if epigenetic modifications in T cells were associated with current asthma and explored whether such modifications were associated with second hand smoke exposures. Our study was conducted in a monozygotic twin cohort of adult twin pairs (n = 21) all discordant for asthma. Regulatory T cell (Treg) and effector T cell (Teff) subsets were assessed for levels of cellular function, protein expression, gene expression and CpG methylation within Forkhead box P3 (FOXP3) and interferon gamma-γ (IFNγ) loci. Comparisons by asthma and current report of exposure to second hand smoke were made. Treg from asthmatic discordant twins demonstrated decreased FOXP3 protein expression and impaired Treg function that was associated with increased levels of CpG methylation within the FOXP3 locus when compared to their non-asthmatic twin partner. In parallel, Teff from discordant asthmatic twins demonstrated increased methylation of the IFNγ locus, decreased IFNγ expression and reduced Teff function when compared to Teff from the non-asthmatic twin. Finally, report of current exposure to second hand smoke was associated with modifications in both Treg and Teff at the transcriptional level among asthmatics. The results of the current study provide evidence for differential function of T cell subsets in monozygotic twins discordant for asthma that are regulated by changes in DNA methylation. Our preliminary data suggest exposure to second hand smoke may augment the modified T cell responses associated with asthma.

Differential rates of relapse in subgroups of male and female smokers

Subjects for this study were 265 participants of stop-smoking clinics (mean age = 42.6 years; average number of cigarettes smoked daily = 26.0) who were examined before and immediately after cessation and then followed for 1 year. The objective of this study was to identify subgroups of smokers with different rates of relapse using tree-structured survival analysis, a multivariate approach to classification. Five distinct subgroups that differed with respect to the rate of relapse were identified: (I) subjects (n = 15) with very low precessation cotinine levels (< or = 129 ng/ml), who had an exceptionally low rate of relapse (mean abstinence time = 270 days); (II) women 32 years old and younger (n = 24), who had a very high rate of relapse (mean abstinence time = 30.5 days); (III) women over 32 years old (n = 121), with the next highest rate of relapse (mean abstinence time = 98.9 days); (IV) men 36 years old and younger (n = 31), who had a mean abstinence time of 196.7 days; and (V) men over 36 years old (n = 74), who abstained an average of 130.2 days before relapsing. Relapse curves for all groups (except III vs V) differed significantly from each other, p < 0.05. Results indicate that this approach can identify interactions among individual differences that are variably associated with relapse rates. Identification of relapse subgroups may have important implications for both theories and treatment of smoking relapse.

Bupropion SR and counseling for smoking cessation in actual practice: Predictors of outcome

To date, only one study has been published on individual characteristics associated with outcome following standard treatment with bupropion SR for smoking cessation. To investigate treatment outcome beyond the 6-week end-of-treatment point, the present study examined characteristics associated with more clinically relevant smoking endpoints following treatment with bupropion SR in a large health care system. A total of 1,524 smokers (649 men and 875 women) of average age 45.1 years were randomized to receive one of four combinations of bupropion SR (150 or 300 mg) and behavioral counseling (tailored mailings or proactive telephone counseling) and assessed for point-prevalent smoking status at 3 and 12 months. Multiple logistic regression analyses of potential risk factors for 12-month point-prevalent smoking and for persistent smoking (point-prevalent smoking at both follow-ups) following treatment were conducted for men and women combined and separately. Risk factors for smoking at both endpoints in the combined sample included treatment with tailored mailings, female gender, younger age, higher levels of tobacco dependence, shorter previous quit attempts, previous use of nicotine replacement therapy, and report of current depressive symptoms or lifetime depression. Risk factors for smoking following treatment identified in women only included treatment with the lower dose of bupropion SR, younger age, and higher perceived stress, whereas those that were unique to men included the presence of lifetime depression. The results are discussed in terms of their implications for the need for more effective treatments in general, and the role of individual differences in the likelihood of returning to smoking following treatment for quitting.

Behavioral Counseling and Varenicline Treatment for Smoking Cessation

BACKGROUND Smoking remains the primary preventable cause of death and illness in the U.S. Effective, convenient treatment programs are needed to reduce smoking prevalence. PURPOSE This study compared the effectiveness of three modalities of a behavioral smoking-cessation program in smokers using varenicline. METHODS Current treatment-seeking smokers (n=1202) were recruited from a large healthcare organization between October 2006 and October 2007. Eligible participants were randomized to one of three smoking-cessation interventions: web-based counseling (n=401); proactive telephone-based counseling (PTC; n=402); or combined PTC and web counseling (n=399). All participants received a standard 12-week FDA-approved course of varenicline. Self-report determined the primary outcomes (7-day point prevalent abstinence at 3- and 6-month follow-ups); the number of days varenicline was taken; and treatment-related symptoms. Behavioral measures determined utilization of both the web- and Phone-based counseling. RESULTS Intent-to-treat analyses revealed relatively high percentages of abstinence at 3 months (38.9%, 48.5%, 43.4%) and at 6 months (30.7%, 34.3%, 33.8%) for the web, PTC, and PTC-web groups, respectively. The PTC group had a significantly higher percentage of abstinence than the web group at 3 months (OR=1.48, 95% CI=1.12, 1.96), but no between-group differences in abstinence outcomes were seen at 6 months. CONCLUSIONS Phone counseling had greater treatment advantage for early cessation and appeared to increase medication adherence, but the absence of differences at 6 months suggests that any of the interventions hold promise when used in conjunction with varenicline.

Self-reported abstinence effects in the first month after smoking cessation

The present study evaluated self-reported subjective complaints (29 single items and 11 scales) at precessation, on quit day, and on Days 1, 2, 3, 7, 14, 21, and 28 after cessation in 46 healthy quitters who remained abstinent for the first month after cessation (biochemically confirmed). Also tested on the same schedule were 29 nonsmokers matched for age and gender. Specific criteria were set for transient and offset effects based on the direction, magnitude, and time course of changes in symptoms after cessation. Results indicated that single-item anger, anxiety, depression, difficulty concentrating, irritability, restlessness, dizziness, and nausea, and the Shiffman-Jarvik Stimulation/Sedation Subscale, the Perceived Stress scale, and the POMS anger, confusion, and tension subscales met the criteria for transient effects, and that single-item desire to smoke, cough, and headache, and the Shiffman-Jarvik Psychological Subscale met the criteria for offset effects. These findings help to clarify which subjective complaints after smoking cessation are transient effects and which are offset effects, a distinction with important implications for understanding nicotine dependence and for designing pharmacological and nonpharmacological interventions for smoking cessation.