Differential melatonin alterations in cerebrospinal fluid and serum of patients with major depressive disorder and bipolar disorder.

BACKGROUND: Melatonin, which plays an important role for regulation of circadian rhythms and the sleep/wake cycle has been linked to the pathophysiology of major depressive and bipolar disorder. Here we investigated melatonin levels in cerebrospinal fluid (CSF) and serum of depression and bipolar patients to elucidate potential differences and commonalities in melatonin alterations across the two disorders. METHODS: Using enzyme-linked immunosorbent assays, CSF and serum melatonin levels were measured in 108 subjects (27 healthy volunteers, 44 depressed and 37 bipolar patients). Covariate adjusted multiple regression analysis was used to investigate group differences in melatonin levels. RESULTS: In CSF, melatonin levels were significantly decreased in bipolar (P<0.001), but not major depressive disorder. In serum, we observed a significant melatonin decrease in major depressive (P=0.003), but not bipolar disorder. No associations were found between serum and CSF melatonin levels or between melatonin and measures of symptom severity or sleep disruptions in either condition. CONCLUSION: This study suggests the presence of differential, body fluid specific alterations of melatonin levels in bipolar and major depressive disorder. Further, longitudinal studies are required to explore the disease phase dependency of melatonin alterations and to mechanistically explore the causes and consequences of site-specific alterations.

Assessment of prescribed increases in physical activity: application of a new method for microprocessor analysis of heart rate.

A portable solid-state recorder-display system was used to measure and analyze heart rate during the waking hours of 3 consecutive days in free-living sedentary normal middle-aged men who were randomized to undergo 3 regimens of physical activity during a 12-week period: low-intensity exercise training at home (n = 21), high-intensity exercise training at home (n = 23) and customary activity (n = 20). This was done to determine whether the system could detect changes in heart rate and, indirectly, in physical activity within the 3 groups. In both training groups the percentage of total recorded time spent within the prescribed high or low heart rate range recorded at 6 or 12 weeks increased significantly (p less than 0.05), whereas control subjects showed no increase above baseline values. Peak oxygen consumption increased by 8% and 17% in men undergoing low- and high-intensity training, whereas in control subjects it did not change. This solid-state system reliably measures prescribed increases in heart rate and provides an indirect measure of physical activity in normal sedentary men undergoing exercise training at home.

Effects of low- and high-intensity home-based exercise training on functional capacity in healthy middle-aged men.

The effects of 12 weeks of home-based exercise training on peak oxygen consumption (VO2 max) in healthy sedentary middle-aged men, mean age 49 +/- 6 years, were evaluated. Twenty-one men trained at low intensity, 23 trained at high intensity and 20 were control subjects. Individually prescribed low- and high-intensity training was performed 5 times per week within a range of 42 to 60% and 63 to 81% of baseline VO2 max, corresponding to average heart rates of 102 to 122 and 128 to 148 beats/min, respectively. Caloric expenditure per training session approximated 350 kcal in both groups; adherence was at least 90% in both groups. VO2 max increased 8% in patients who trained at low intensity, 17% in those who trained at high intensity (both p less than 0.001), and not at all in control subjects. Low-intensity exercise training at home significantly augments functional capacity in healthy sedentary middle-aged men.

Ski injuries.

A group of 147 injuried skiers seen in the emergency room of a midwestern hospital was studied. There were almost twice as many males as females, and lower-extremity injuries outnumbered upper-extremity injuries two to one. Leg injuries tended to occur in beginners whose bindings failed to release. Upper-extremity injuries were prevalent in better skiers whose bindings released properly. Frequent binding checks only slightly improved the likelihood of proper binding function.