Biomedical subjects
Publications and source records attributed to Wesley K Thompson.
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Compared to younger adults, seniors (> or = 60 yrs) often adopt a highly regular lifestyle, perhaps as an adaptive response to age-related changes in their sleep and circadian rhythms. At baseline, diary measures of lifestyle regularity (SRM-5) were obtained from 104 seniors of three separate groups. Thirty-three subjects were challenged by spousal bereavement or the need to care for a spouse at home with dementia (Challenged); 33 were suffering from formally diagnosed (DSM-IV) insomnia (Insomnia); and 38 were healthy, well-functioning older seniors in the second half of their eighth decade of life or later (Healthy Older). The objective of this study was to determine whether lifestyle regularity increased as a function of age within each of these three senior groups. Overall, age was significantly correlated with SRM-5 (r=0.41, p<0.001), with the SRM score increasing by 0.67 units/decade. The same was true for the Challenged and Insomnia groups, which also showed a significant correlation between SRM and age (Challenged: r=0.48, p<0.01; Insomnia: r=0.36, p<0.05), though with a slightly faster rate of SRM increase in the Challenged (0.95 units/decade) than Insomnia (0.55 units/decade) group. Perhaps there was no correlation between age and SRM (r=0.07, n.s.) in the Healthy Older group due to the small age range, although this group did have a higher overall SRM score than the other two groups (p<0.01). The study thus confirmed that the previously observed increase in lifestyle regularity over the adult lifespan persists into later life. This may represent an adaptive behavioral response that might be used in future therapeutic approaches.
The aim of this study was to determine whether naturally occurring inter-individual and intra-individual differences in bedtime selection in the elderly might be lawfully related to the amount of sleep that is obtained. A total of 128 seniors (63f, 65m) aged 70-92 years each provided a week of sleep diary data yielding a total of 896 subject-nights for analysis. From each subject-night the diary was used to derive measures of time in bed (TIB) and total sleep time (TST). These measures were used as dependent variables in mixed-effect linear models (nights nested within subjects) with the independent variable being bedtime for that subject-night, arbitrarily expressed as minutes since 19:00 hours. Although there were strong inter-individual and intra-individual differences, for both genders, bedtime had a statistically significant effect (P < 0.001) on both TIB and TST. We observed that later bedtimes were associated with less time in bed and less time asleep. On average between 7 and 8 min of less TIB and TST were associated with each 10-min delay in bedtime from 19:00 hours. These results are interpreted in terms of increases in sleep being derived from living in a better harmony with an earlier peaking circadian pacemaker characteristic of older age, although other possible mechanisms are also considered (e.g. age-dependent alterations in phase angle and homeostatic sleep need).
OBJECTIVE: We studied the relationship between number of medical comorbidities in patients with bipolar I disorder and their demographic and clinical characteristics. METHOD: Data were from 174 patients in the acute phase of the Pittsburgh Maintenance Therapies in Bipolar Disorder (MTBD) study, a randomized controlled trial comparing Interpersonal and Social Rhythm Therapy to an intensive clinical management approach for individuals with a lifetime diagnosis of bipolar I disorder or schizoaffective disorder, manic type, according to Research Diagnostic Criteria, who were receiving adjunctive protocol-driven pharmacotherapy. Patients entered the MTBD study from 1991 to 2000. We examined the acute-phase Hamilton Rating Scale for Depression (HAM-D) and Bech-Rafaelsen Mania Scale scores, demographics, clinical history, and medical comorbidities. RESULTS: Patients with a high number of medical comorbidities had longer duration of both lifetime depression (p = .02) and lifetime inpatient depression treatment (p = .04), had higher baseline HAM-D score (p = .01), and were more likely to be treated for a depressed clinical state during the acute phase of the MTBD study (p = .05). Moreover, higher severity of baseline medical comorbidities predicted slower decreases in HAM-D score among depressed (p = .004) and mixed/cycling (p = .003) patients even after controlling for baseline HAM-D score. CONCLUSIONS: Medical illness is correlated with several indicators of poorer prognosis and outcome in bipolar I disorder. Not only do preventing and treating medical comorbidities in bipolar patients decrease the morbidity and mortality related to physical illness, but they could also enhance psychological well-being and possibly improve the course of bipolar illness. Identification of characteristics in bipolar I patients that are correlated to increased risk for medical comorbidities is a fundamental step in understanding the nature of the relationship between bipolar disorder and medical illness.
This paper develops a general approach for dealing with parametric transformations of covariates for longitudinal data, where the responses are modeled marginally and generalized estimating equations (GEEs) are used for estimation of regression parameters. We propose an iterative algorithm for obtaining regression and transformation parameters from estimating equations, utilizing existing software for GEE problems. The algorithmic technique is closely related to that used in the Box-Tidwell transformation in classical linear regression, but we develop it under the GEE setting and for more general transformation functions. We provide supporting theorems for consistency and asymptotic Normality of the estimates. Inference between two nested models is also considered. This methodology is applied to two data sets. One consists of pill dissolution data, the other is taken from the Pittsburgh Youth Study (PYS). The PYS is a prospective longitudinal study of the development of delinquency, substance use, and mental health in male youth. We use the model-based parametric approach to examine the association between alcohol use at an early stage of adolescent development and delinquency over the course of adolescence.