Gender specificity in the prediction of clinically diagnosed depression. Results of a large cohort of Belgian workers.

BACKGROUND: The recent increase in the incidence of clinical depression represents a major public health and socio-economical burden. Depression has its roots in both professional and private domains but few epidemiological studies have looked at predictors of long term clinical depression as defined by a sick-leave of 28 days or more and a diagnosis by a general practitioner in both genders. OBJECTIVES: To study baseline predictors of long term spells of clinical depression within the framework of a large prospective study, the Belstress Study, in 6,659 men and 2,737 women aged 35-59 years at baseline survey. METHODS: Kaplan-Meyer survival curves and Cox regression models were used in order to relate long term clinical depression defined by a sick-leave of 28 days or more to baseline socio-demographic and work and non-work variables. RESULTS AND CONCLUSIONS: Density incidence of long term clinical depression is 0.5 years and 1.1/1,000 persons/months for men and women respectively. In univariate analyses specific gender predictors were observed as for men predictors besides level of education, were work related: high job-strain OR 1.67 (CI 95% 1.03; 2.71) and work dissatisfaction OR 1.78 (CI 95% 1.09; 2.91) whereas for women baseline predictors are related to private life dissatisfaction OR 1.84 (CI 95% 1.16; 2.91) and to a lesser degree low social support from co-workers OR 1.50 (CI 95% 0.93; 2.40). In both genders baseline severe depression symptoms defined by a CES-D score of percentile 90 or above is a predictor of long term sick-leave for clinical depression. In multivariate analyses, in a model without baseline CES-D high job-strain and job dissatisfaction remain independent predictors for incident clinical depression in men whereas only private life dissatisfaction remains a significant predictor in women. When added to the model CES-D is the most powerful predictor of clinical depression in both genders. Together with level of education, work dissatisfaction remains borderline significant in men whereas private life dissatisfaction remains an independent predictor for clinical depression in women. In men baseline symptoms of depression alleviate the impact of high job-strain on incident clinical depression whereas in women, private life dissatisfaction remains an independent predictor of clinical depression.

Autonomic responses to sighs in healthy infants and in victims of sudden infant death.

OBJECTIVE: Sigh, defined as an isolated breath with an increased tidal volume, can be associated with abrupt changes in heart rate (HR) or blood oxygenation. Sigh may be followed by a central apnea. As impairment of autonomic control was postulated in future SIDS victims, we hypothesized that their autonomic responses to sighs were different from those of healthy control infants. METHODS: Sighs followed by central apnea were studied in the sleep recordings of 18 infants who eventually died of SIDS and of 18 control infants. The infants of the two groups were matched for sex, gestational age, postnatal age, weight at birth and sleep position during sleep recording. HR autoregressive power spectral analysis was performed on RR intervals preceding and following sighs. RESULTS: In all infants, most sighs followed by an apnea were found in NREM sleep. Compared to the control infants, the future SIDS victims were characterized by a greater sympathovagal balance and a lower parasympathetic tonus before the sighs. Following the sighs, no more differences were found in NREM sleep. CONCLUSION: Based on the present findings, it can be postulated that sighs contribute to reset autonomic tonus during NREM sleep.

Cardiac autonomic characteristics in infants sleeping with their head covered by bedclothes.

The risk of Sudden Infant Death Syndrome is increased in infants sleeping with their head covered by bedding items. This study was designed to evaluate cardiac autonomic nervous controls in infants sleeping with the head covered by bedclothes. Sixteen healthy infants with a median age of 12 weeks (range 9-13 weeks) were recorded polygraphically for one night. While they slept in their usual supine position, a bedsheet was placed over their head for about 45 min. All infants were challenged with the head covered and with the head free during both rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. Sleep, breathing and heart rate (HR) characteristics were recorded simultaneously, together with rectal and pericephalic temperatures. In both head-free and head-covered conditions, autoregressive spectral analysis of HR was evaluated as a function of sleep stages. During the head-covered periods, parasympathetic tonus decreased and sympathetic activity increased in both REM and NREM sleep. Compared with the head-free periods, the head-covered sleep periods were characterized by greater rectal (P = 0.012) and pericephalic temperatures (P = 0.002). Covering the infant's head with a bedsheet was associated with significant changes in autonomic balance. The finding could be related to an elevation in temperatures within the infant's microenvironment.

Decreased arousals in infants who sleep with the face covered by bedclothes.

OBJECTIVE: The risk of becoming a victim of sudden infant death syndrome is increased in infants who sleep with their face under bedding items. The present study was designed to evaluate auditory arousal thresholds of infants who sleep with their face covered by bedclothes. METHODS: Twenty healthy infants with a median age of 11.5 weeks (range: 4-22 weeks) were recorded polygraphically for 1 night. Although they slept in their usual supine position, a bed sheet was placed over their face for 60 minutes. Fifteen of the 20 infants were chosen at random and were exposed to white noises of increasing intensities to determine their auditory arousal thresholds. All infants were challenged with the face covered and with the face free during both rapid eye movement (REM) and non-REM (NREM) sleep. Seven infants were first challenged with the face covered, and 8 were challenged with the face free. The following variables were recorded simultaneously: electroencephalogram, breathing and heart rates, and rectal and pericephalic temperatures. In 5 infants who were not exposed to the auditory challenges, end tidal CO2 was recorded for 30 minutes while sleeping with the face covered. RESULTS: During REM sleep, arousals occurred for significantly more intense auditory stimuli when the infant's face was covered than when free. No significant difference was seen in NREM sleep. Compared with the face-free periods, the face-covered sleep periods were characterized by greater rectal and pericephalic temperatures, a greater density of body movements, and a decrease in NREM sleep. Respiratory frequency was increased during the face-covered periods in both REM and NREM sleep. No differences were seen in the frequency or duration of apnea. There was a tendency for heart rate to increase during both sleep stages when the face was covered, compared with the face-free periods, but the changes were not statistically significant. A positive correlation was found between pericephalic temperatures and arousal thresholds (r = 0.60) during REM sleep. End tidal CO2 values increased when the face was covered, reaching a maximum value during the first 5 minutes of the experiment. No fall in oxygen saturation was seen. CONCLUSIONS: Covering the infant's face with a bed sheet was associated with a significant increase in auditory arousal threshold. The finding could be related to an elevation in temperatures within the infant's microenvironment.