A prospective 12-year study of subsyndromal and syndromal depressive symptoms in unipolar major depressive disorders

BACKGROUND: Investigations of unipolar major depressive disorder (MDD) have focused primarily on major depressive episode remission/recovery and relapse/recurrence. This is the first prospective, naturalistic, long-term study of the weekly symptomatic course of MDD. METHODS: The weekly depressive symptoms of 431 patients with MDD seeking treatment at 5 academic centers were divided into 4 levels of severity: (1) depressive symptoms at the threshold for MDD; (2) depressive symptoms at the threshold for minor depressive or dysthymic disorder (MinD); (3) subsyndromal or subthreshold depressive symptoms (SSDs), below the thresholds for MinD and MDD; and (4) no depressive symptoms. The percentage of weeks at each level, number of changes in symptom level, and medication status were analyzed overall and for 3 subgroups defined by mood disorder history. RESULTS: Patients were symptomatically ill in 59% of weeks. Symptom levels changed frequently (1.8/y), and 9 of 10 patients spent weeks at 3 or 4 different levels during follow-up. The MinD (27%) and SSD (17%) symptom levels were more common than the MDD (15%) symptom level. Patients with double depression and recurrent depression had more chronic symptoms than patients with their first lifetime major depressive episode (72% and 65%, respectively, vs 46% of follow-up weeks). CONCLUSION: The long-term weekly course of unipolar MDD is dominated by prolonged symptomatic chronicity. Combined MinD and SSD level symptoms were about 3 times more common (43%) than MDD level symptoms (15%). The symptomatic course is dynamic and changeable, and MDD, MinD, and SSD symptom levels commonly alternate over time in the same patients as a symptomatic continuum of illness activity of a single clinical disease.     

Age-dependent U-shaped risk functions and Aalen's additive risk model

Epidemiologic studies of time to some failure often show a quadratic relation between the risk of failure and covariate(s). We study the nadir for a given covariate, i.e., the value of the covariate associated with the lowest risk (supposing a U-shape), within Aalen's additive risk model. This model was applied since the effect of the covariate(s) is allowed to vary over time and, as a consequence, a given nadir can vary over time. We propose a test for the null hypothesis that the nadir is time independent and, if this is the case, an estimate of the nadir. Large sample properties of the test statistic and estimator are derived. The methods are illustrated with data where time to death is related to body mass index.     

Hall mobility in dielectrically isolated single-crystal silicon films defined by electrochemical etching

The majority-carrier Hall mobility has been measured in thin, single-crystal silicon films defined by electrochemical etching. Both n-type and p-type films with dopant concentrations of about 10¹⁵ cm^?3 were studied. The mobilities observed in p-type thin films and in epitaxial control samples were almost identical while the mobilities measured in n-type films were markedly less than those in epitaxial control samples. This apparent anomaly is attributed to the presence of an n-type surface-charge layer with lower carrier mobility near the bottom of the thin films, although it may possibly be related to voids formed in the n-type films. Measurements on very thin samples indicated that an t-type surface layer is left on the top surface of p-type films immediately after electrochemical etching.     

Utilization of fine-needle aspiration cytology and flow cytometry in the diagnosis and subclassification of primary and recurrent lymphoma

The aim of this study was to assess and compare spinal cord injured (SCI) and traumatic brain injured (TBI) persons and people from the general population concerning partner relationships, functioning, mood and global quality of life. One hundred and sixty seven SCI persons, 92 TBI persons and 264 controls participated in the study. The median age was: SCI persons 33 years (range 19 to 79 years), TBI persons 40 years (range 20 to 70 years), and controls 31 years (range 19 to 79 years). Age at injury ranged among SCI persons from 14 to 76 years (Md 28 years), and among TBI persons from 16 to 56 years (Md 32 years). Half of the SCI group (51%), 58% of the TBI group and 59% of the controls had a stable partner relationship at the time of the investigation. Many of these SCI and TBI relationships (38% and 55% respectively) were established after injury. Both SCI and TBI persons showed significantly more depressive feelings compared with the controls. Perceived quality of life (global QL rating) was significantly lower in the SCI group compared with the controls, whereas the ratings of TBI persons and controls did not differ significantly. SCI and TBI persons did not differ significantly in level of education, perceived quality of life or distress. In all three groups, global quality-of-life ratings were significantly lower among single persons compared to those with a partner relationship. It was concluded that both SCI and TBI appear to affect overall quality of life and mental well-being negatively. The number of partner relationships contracted after injury among both SCI and TBI persons indicates, however, that the injury is not a major barrier to establishing close partner relationships. Being in good spirits, that is, lack of depressive feelings has a profound impact on the perception of a high quality of life in all three groups. For the SCI and TBI persons, a high level of physical and social independence were further positive determinants of a perceived high quality of life.