Changes in cardiac function in Navy divers during four days of successive dives in very cold diving conditions

INTRODUCTION AND METHODS

There is limited knowledge of cumulative effect of repetitive cold-water diving on cardiac function. Single cold dives cause some known cardiological risks, such as malign arrhythmia, due to a concurrent activation of the sympathetic and parasympathetic autonomic nervous system. A previous study from warmer water dives has shown that successive dives cause a decrease in vagal tone and a less responsive cardiovascular system. The aim of this study was to evaluate changes in cardiac function with 2D echocardiography during 4 days of diving in near-freezing water.

RESULTS

Left ventricle systolic function measures did not show any uniform changes. E/A ratio seemed to decrease successively with the number of dives. The diastolic tissue velocity of relaxing basal septum (e') showed a decreasing trend as well. Diastolic blood pressure seemed to increase from predive (mean: 83 RR mmHg) to postdive values (mean: 87 RR mmHg) (p=NS). Heart rate decreased significantly from predive (mean: 71 bpm, range: 56-103) to postdive values (mean: 60 bpm, range: 37-88) (p < 0.03).

DISCUSSION AND CONCLUSIONS

The study was conducted in very cold condition and with limited number of divers. Results of this preliminary study suggested a decreasing trend in left ventricular diastolic function in successive cold dives. Cumulative changes in cardiac function may cause health risks that need to be considered during cold water diving operations.

Snoring was related to self-reported daytime sleepiness and tiredness in young adults performing compulsory conscript service

STUDY OBJECTIVES

In young adults performing compulsory military service, fatigue and somnolence are common and presumably associated with objective or self-reported sleep deprivation. We aimed to find out whether objective sleep parameters from ambulatory polysomnography could explain their self-reported tiredness and sleepiness and whether habits were associated with sleep parameters or tiredness.

METHODS

Seventy (67 male, age 18-24 years) participants had their sleep assessed with polysomnography. Their self-reported symptoms and demographic data were obtained from online survey including Epworth Sleepiness Scale, Beck's Depression Inventory, items from Basic Nordic Sleep Questionnaire, Internet Addiction Scale, and lifestyle questions.

RESULTS

Snoring (audio recording, percentage of total sleep time) was associated with self-reported sleepiness (P = .010) and tiredness (P = .030) and snoring seemed to, partially, explain sleepiness (P = .029). Twenty-six percent of the conscripts had self-reported sleep deprivation (mismatch between reported need for sleep and reported sleep). Self-reported sleep deprivation was significantly associated with somnolence (P = .016) and fatigue (P = .026). Smartphone usage, both average time (P = .022) and frequency of usage (P = .0093) before bedtime, was associated with shorter total sleep time. On average, objective sleep time was rather short (7 hours, 6 minutes), sleep efficiency high (94.9%), proportion of N3 sleep high (27.7%), and sleep latency brief (9 minutes)-suggesting that many of the conscripts might have chronic partial sleep deprivation.

CONCLUSIONS

Snoring might predispose to tiredness in presumably healthy young adults. Conscripts may have partial sleep deprivation.

CITATION

Orjatsalo M, Toppila J, Heimola M, et al. Snoring was related to self-reported daytime sleepiness and tiredness in young adults performing compulsory conscript service. J Clin Sleep Med. 2023;19(2):243-251.

Hyperventilation and Hypoxia Hangover During Normobaric Hypoxia Training in Hawk Simulator

Introduction: In military aviation during high-altitude operations, an oxygen or cabin pressure emergency can impair brain function and performance. There are variations in individuals’ physiological responses to low partial pressure of oxygen and hypoxia symptoms can vary from one exposure to another. The aim of this study was to evaluate how normobaric hypoxia (NH) affects pilots’ minute ventilation and 10 min afterwards on Instrument Landing System (ILS) flight performance in Hawk simulator during a tactical flight sortie.

Methods: Fifteen volunteer fighter pilots from the Finnish Air Force participated in this double blinded, placebo controlled and randomized study. The subjects performed three flights in a tactical Hawk simulator in a randomized order with full flight gear, regulators and masks on. In the middle of the flight without the subjects’ knowledge, 21% (control), 8% or 6% oxygen in nitrogen was turned on. Minute ventilation (VE) was measured before, during NH and after NH. Forehead peripheral oxygen saturation (SpO₂), wireless ECG and subjective symptoms were documented. The flights were conducted so that both subjects and flight instructors were blinded to the gas mixture. The pilots performed tactical maneuvers at simulated altitude of 20,000 ft or 26,000 ft until they recognized the symptoms of hypoxia. Thereafter they performed hypoxia emergency procedures with 100% oxygen and returned to base (RTB). During the ILS approach, flight performance was evaluated.

Results: The mean VE increased during NH from 12.9 L/min (21% O2 on the control flight) to 17.8 L/min with 8% oxygen (p < 0.01), and to 21.0 L/min with 6% oxygen (p < 0.01). Ten minutes after combined hyperventilation and hypoxia, the ILS flight performance decreased from 4.4 (control flight) to 4.0 with 8% oxygen (p = 0.16) and to 3.2 with 6% oxygen (p < 0.01). A significant correlation (r = -0.472) was found between the subjects’ VE during 6% oxygen exposure and the ILS flight performance.

Discussion: Hyperventilation during NH has a long-lasting and dose-dependent effect on the pilot’s ILS flight performance, even though the hypoxia emergency procedures are executed 10 min earlier. Hyperventilation leads to body loss of carbon dioxide and hypocapnia which may even worsen the hypoxia hangover.

Large lungs may predict increased air trapping in navy divers

Navy divers tend to have large lungs and low expiratory flow rates in the terminal portion of a spirogram. We examined Finnish Navy divers for the presence of air trapping, airway obstruction, and functional airway compression, and their association with lung volumes. Divers (n = 57) and non-diving men (n = 10) underwent a variety of pulmonary function tests. The amount of trapped air was calculated as the subtraction of the total lung capacity (TLC) measured in a single-breath helium dilution test from the TLC in body plethysmography (TLCb). Mean vital capacity (VC) was 6.4 L in the divers versus 5.8 L in the controls (p = 0.006) and TLCb 8.9 L in the divers versus 8.1 L in the controls (p = 0.002). No difference existed between them in the amount of trapped air. However, we found break points in a linear regression model (Davies test) between trapped air and several pulmonary parameters. Those individuals above the break points had lower ratio of forced expiratory volume in first second to forced vital capacity, lower resistance of airways, and higher reactance than those below the break points. In conclusion, navy divers had larger lungs than controls. Large lung volumes (VC >7.31 L or >122% of predicted value) were associated with air trapping. Furthermore, large volumes of air trapping (>1.1 L) were associated with increased residual volume (RV) and RV/TLCb. Despite no concurrent obstruction, functional airway compression, or reduced diffusing capacity, this slowly ventilated trapped air might remain disadvantageous for divers.

A Randomized Controlled Trial Protocol for Using an Accelerometer-Smartphone Application Intervention to Increase Physical Activity and Improve Health among Employees in a Military Workplace

Physical activity is beneficial for improving health and reducing sick leave absences. This article describes a protocol for an intervention using an interactive accelerometer smartphone application, telephone counselling, and physical activity recordings to increase the physical activity of workers in the military and improve their health. Under the protocol, employees from six military brigades in Finland will be randomly assigned to intervention and control groups. The intervention group’s participants will use accelerometers to measure their daily physical activities and their quality of sleep for six months. They will receive feedback based on these measurements via a smartphone application. The intervention group’s participants will be encouraged to exercise for two hours per week during working hours, and to participate in telephone counselling. The control group’s participants will continue with their normal exercise routines, without the accelerometer or feedback. The participants of both groups will be measured at the baseline, after the intervention period, and six months after the end of the intervention. The measurements will include accelerometer recordings, biochemical laboratory tests, body composition measurements, physical fitness tests, and questionnaires on sociodemographic factors, physical activities, and health. The primary outcomes will indicate changes in physical activity, physical fitness, and sick leave absences. The findings will help to develop a straightforward and cost-effective model for supporting the health and working capabilities of employees in the military and other workplaces.

Chronotype as self-regulation: morning preference is associated with better working memory strategy independent of sleep

Study Objectives

We set out to examine how chronotype (diurnal preference) is connected to ability to function in natural conditions where individuals cannot choose their sleep schedule. We conducted a cross-sectional study in military conscript service to test the hypothesis that sleep deprivation mediates the adverse effects of chronotype on cognitive functioning. We also examined the effects of time of day.

Methods

One hundred forty participants (ages 18-24 years) completed an online survey, including the Morningness-Eveningness Questionnaire and a Cambridge Neuropsychological Test Automated Battery. Most (n = 106) underwent an actigraphy recording. After bivariate analyses, we created a mediation model (self-reported sleepiness and sleep deprivation mediating effect of chronotype on cognition) and a moderation model (synchrony between most alert time and testing time).

Results

Reaction times in inhibition task correlated negatively with sleep efficiency and positively with sleep latency in actigraphy. There was no relation to ability to inhibit responses. More significantly, spatial working memory performance (especially strategicness of performance) correlated positively with morning preference and negatively with sleep deprivation before service. Synchrony with most alert time of the day did not moderate these connections. No other cognitive task correlated with morningness or sleep variables.

Conclusions

In line with previous research, inhibitory control is maintained after insufficient sleep but with a tradeoff of slower performance. The connection between morning preference and working memory strategy is a novel finding. We suggest that diurnal preference could be seen as an adaptive strategy, as morningness has consistently been associated with better academic and health outcomes.

Diving Responses in Experienced Rebreather Divers: Short-Term Heart Rate Variability in Cold Water Diving

Introduction

Technical diving is very popular in Finland throughout the year despite diving conditions being challenging, especially due to arctic water and poor visibility. Cold water, immersion, submersion, hyperoxia, as well as psychological and physiological stress, all have an effect on the autonomic nervous system (ANS).

Materials and methods

To evaluate divers' ANS responses, short-term (5 min) heart rate variability (HRV) during dives in 2-4°C water was measured. HRV resting values were evaluated from separate measurements before and after the dives. Twenty-six experienced closed circuit rebreather (CCR) divers performed an identical 45-meter decompression dive with a non-physical task requiring concentration at the bottom depth.

Results

Activity of the ANS branches was evaluated with the parasympathetic (PNS) and sympathetic (SNS) indexes of the Kubios HRV Standard program. Compared to resting values, PNS activity decreased significantly on immersion with face out of water. From immersion, it increased significantly with facial immersion, just before decompression and just before surfacing. Compared to resting values, SNS activity increased significantly on immersion with face out of water. Face in water and submersion measures did not differ from the immersion measure. After these measurements, SNS activity decreased significantly over time.

Conclusion

Our study indicates that the trigeminocardiac part of the diving reflex causes the strong initial PNS activation at the beginning of the dive but the reaction seems to decrease quickly. After this initial activation, cold seemed to be the most prominent promoter of PNS activity - not pressure. Also, our study showed a concurrent increase in both SNS and PNS branches, which has been associated with an elevated risk for arrhythmia. Therefore, we recommend a short adaptation phase at the beginning of cold-water diving before physical activity.

Ten-year changes in the psychosocial well-being, psychopathology, substance use, suicidality, bullying, and sense of coherence of 18-year-old males: a Finnish population-based time-trend study

We studied Finnish 18-year-old males attending obligatory military call-up assessments in 1999 (n = 2340) and 2009 (n = 4309) on time-trend changes in psychosocial well-being, psychopathology, substance use, suicidality, bullying, and sense of coherence. Subjects filled in questionnaires, including the Young Adult Self-Report (YASR) for psychopathology and the Orientation to Life Questionnaire (SOC-13) for sense of coherence. The prevalence of minor mental health problems in the last 6 months decreased from 22.3% in 1999 to 18.6% in 2009 (OR 0.8, 95% CI 0.7-0.9), whereas severe mental health problems remained stable. Suicidal thoughts decreased from 5.7 to 3.7% (OR 0.6, 95% CI 0.5-0.8). The use of illicit drugs decreased from 6.0 to 4.7% (OR 0.8, 95% CI 0.6-0.95), but being drunk at least once a week increased from 10.3 to 13.4% (OR 1.3, 95% CI 1.0-1.5). Attention problems increased in YASR syndrome domains (mean score 2.9 vs 3.2, p < 0.001) and so did somatic complains (mean score 1.7 vs 1.9, p = 0.005). The SOC-13 scores remained stable. The percentage of males who had studied during the past 6 months increased from 91.4 to 93.4% (OR 1.3, 95% CI 1.1-1.6), while being employed decreased from 64.9 to 49.4% (OR 0.5, 95% CI 0.5-0.6). The positive findings included reductions in the prevalence of suicidal thoughts and the use of illicit drugs, but being drunk at least once a week increased. Self-reported somatic problems and attention problems increased. Despite changes in society and family structures, there were only minor overall changes in psychopathology.

Comparison of argon and air as thermal insulating gases in drysuit dives during military Arctic diving equipment development tests

INTRODUCTION

It is vital to protect divers from the cold, particularly in Arctic conditions. The insulating gas layer within the drysuit is crucial for reducing heat loss. The technical diving community has long claimed the superiority of argon over air as an insulating gas. Although argon is widely used, previous studies have shown no significant differences between the two gases. Owing to its lower heat conductivity, argon should be a better thermal insulating gas than air.

METHODS

The study aimed to determine whether argon is beneficial for reducing heat loss in divers during development of military drysuit diving equipment in Arctic water temperatures. Four divers completed 14 dives, each lasting 45 minutes: seven dives used air insulation and seven used argon insulation. Rectal and eight skin temperatures were measured from which changes in calculated mean body temperature (MBT) were assessed.

RESULTS

There was a significant reduction in area weighted skin temperature over time (0-45 minute) on air dives (ΔTskin = -4.16°C, SE = 0.445, P ⟨ 0.001). On argon dives the reduction was significantly smaller compared to air dives (difference between groups = 2.26°C, SE = 0.358, P ⟨ 0.001). There were no significant changes in rectal temperatures, nor was a significant difference seen between groups.

CONCLUSION

Compared to air, argon may be superior as a drysuit insulating gas in Arctic water temperatures for some divers. Argon used as insulating gas can make diving safer and may diminish the risks of fatal diving accidents and occupational hazard risks in professional diving.

Compulsory military service as a measure of later physical and cognitive performance in male survivors of childhood cancer

BACKGROUND

Compromised physical fitness and cognitive difficulties have been reported as late effects of cancer treatment during childhood. To assess this issue, the military rankings of cancer survivors in medical checkups at call-up, and conscripts' physical and cognitive performance during the first weeks of compulsory military education were compared to those of matched population controls without a history of cancer.

MATERIAL AND METHODS

A total of 1680 male patients born between 1960 and 1992 with a malignancy diagnosed before the age of 16 who were alive at the call-up age (18 years) were identified using the Finnish Cancer Registry, and five age, sex and place of residence matched controls for each patient using the Population Register Centre. Data on military service were gathered from Finnish Defense Forces. A conditional logistic regression analysis, the GEE-method with the cumulative logit link function, the chi-square test, the chi-square test for trend and a one-way analysis of variance were used in different analyses.

RESULTS

Cancer survivors were exempted from military service more often than the controls (p < .001). The fit-for-service frequency was highest for survivors of kidney tumors (68%) and lowest after irradiated brain tumors (19%). In service, the results of the 12-min running test were poorer than those of controls for leukemia/non-Hodgkin lymphoma (p = .03) and brain tumor (p = .01) survivors. Interestingly, the standing long-jump test was the only muscle test for which survivor groups performed worse than controls. Performance on cognitive tests only differed from controls in brain tumor survivors.

CONCLUSIONS

Exemption from service is still common under the current guidelines, but fit-for-service survivors do well in military education. These results can be used for reassuring survivors that completion of military service is possible for those fulfilling the national general guidelines for military fitness.

Total and cause-specific mortality of Finnish military personnel following service in international peacekeeping operations 1990-2010: a comprehensive register-based cohort study

OBJECTIVES

To estimate total and cause-specific mortality after international peacekeeping deployments among the Finnish military peacekeeping personnel in comparison to the general population of similar age and sex.

DESIGN

A register-based study of a cohort of military peacekeeping personnel in 1990-2010 followed for mortality until the end of 2013. Causes of death were obtained from the national Causes of Death Register. The standardised mortality ratio (SMR) for total and cause-specific mortality was calculated as the ratio of observed and expected number of deaths.

SETTING

Finland (peacekeeping operations in different countries in Africa, Asia and in an area of former Yugoslavia in Europe).

PARTICIPANTS

14 584 men and 418 women who had participated in international military peacekeeping operations ending between 1990 and 2010.

INTERVENTIONS

Participation in military peacekeeping operations.

MAIN OUTCOME

Total and cause-specific mortality.

RESULTS

209 men and 3 women died after their peacekeeping service. The SMR for all-cause mortality was 0.55 (95% CI 0.48 to 0.62). For the male peacekeeping personnel, the SMR for all diseases was 0.44 (95% CI 0.35 to 0.53) and for accidental and violent deaths 0.69 (95% CI 0.57 to 0.82). The SMR for suicides was 0.71 (95% CI 0.53 to 0.92).

CONCLUSIONS

Even though military peacekeeping personnel are working in unique and often stressful conditions, their mortality after their service is lower compared with the general population. Military peacekeeping personnel appear to be a selected population group with low general mortality and no excess risk of any cause of death after peacekeeping service.

Demographic Characteristics and Psychiatric Comorbidity of Children and Adolescents Diagnosed with ADHD in Specialized Healthcare

Recent studies have shown an increasing incidence of attention-deficit/hyperactivity disorder (ADHD) among children diagnosed in specialized services. This study aims to describe children with ADHD in Finnish specialized healthcare by reporting the demographic characteristics, time trends in diagnosis, psychiatric comorbidity, and the validity of register-based diagnoses. All the singletons born in Finland between 1991 and 2005 and diagnosed with ADHD by 2011 were identified and their psychiatric comorbidity data was obtained from the Finnish Hospital Discharge Register (FHDR). Parents of 69 patients were interviewed via telephone for a diagnostic validation. A total of 10,409 children were identified with ADHD, with a male: female ratio of 5.3:1 and a psychiatric comorbidity rate of 76.7 %. Of the validation sample 88 % met the diagnostic criteria of ADHD for DSM-IV. There is an increasing trend of ADHD diagnosis among both males and females. Psychiatric comorbidity is common and includes a wide range of disorders among children with ADHD. There was an increase of ADHD diagnoses especially among boys. More attention is needed to detect ADHD among girls in health services. Diagnoses in the FHDR show diagnostic validity and their sociodemographic patterns are in line with previous studies.

Separate and interactive contributions of weak inhibitory control and threat sensitivity to prediction of suicide risk

Biobehavioral dispositions can serve as valuable referents for biologically oriented research on core processes with relevance to many psychiatric conditions. The present study examined two such dispositional variables-weak response inhibition (or disinhibition; INH-) and threat sensitivity (or fearfulness; THT+)-as predictors of the serious transdiagnostic problem of suicide risk in two samples: male and female outpatients from a U.S. clinic (N=1078), and a population-based male military cohort from Finland (N=3855). INH- and THT+ were operationalized through scores on scale measures of disinhibition and fear/fearlessness, known to be related to DSM-defined clinical conditions and brain biomarkers. Suicide risk was assessed by clinician ratings (clinic sample) and questionnaires (both samples). Across samples and alternative suicide indices, INH- and THT+ each contributed uniquely to prediction of suicide risk-beyond internalizing and externalizing problems in the case of the clinic sample where diagnostic data were available. Further, in both samples, INH- and THT+ interactively predicted suicide risk, with individuals scoring concurrently high on both dispositions exhibiting markedly augmented risk. Findings demonstrate that dispositional constructs of INH- and THT+ are predictive of suicide risk, and hold potential as referents for biological research on suicidal behavior.

Distinct variants of extreme psychopathic individuals in society at large: evidence from a population-based sample

This study used model-based cluster analysis to identify subtypes of men who scored high in overall psychopathy (i.e., ≥ 95th percentile on the Triarchic Psychopathy Measure; n = 193) from a larger sample evaluated for service in the Finnish military (N = 4043). Cluster variates consisted of scores on distinct facets of psychopathy together with a measure of negative affectivity. The best-fitting model specified 2 clusters, representing "primary" (n = 110) and "secondary" psychopathy (n = 83) groups. Compared to a low-psychopathy comparison group (n = 1878), both psychopathy subgroups showed markedly elevated levels of externalizing symptoms and criminal behavior. Secondary psychopathic participants also reported high levels of internalizing problems including anxiousness, depression, and somatization, and scored higher on the disinhibition facet of psychopathy relative to the primary group. By contrast, primary psychopathic individuals reported fewer internalizing problems than either the secondary psychopathy or comparison groups and scored higher on the boldness facet of psychopathy. Primary psychopathic participants also had higher rates of violent crimes than the secondary psychopaths. Implications for conceptualizing and studying psychopathy in nonforensic populations are discussed.

Reaction test revealed impaired performance at 6.0 atm abs but not at 1.9 atm abs in professional divers

In order to evaluate the effects of ambient pressure on reaction and movement times we investigated 60 professional divers by a computerized test (Reaction Test). The experiments were carried out four times in a hyperbaric chamber: prior to pressure, at 6.0 and 1.9 atm abs and after decompression. Reaction time varied from 202 to 443 milliseconds (275 +/- 42 ms), but the individual levels remained similar. The reaction time increased between precompression and 6.0 atm abs (p < 0.05), decreased between 6.0 and 1.9 atm abs (p < 0.05) and remained at the original level at 1.9 and 1.0 atm abs after decompression. Ten divers had an increase of more than 1SD in the reaction time at 6.0 atm abs. The number of mistakes was small and not influenced by elevation of pressure. Further, the movement time remained unchanged throughout the experiment. We conclude that the response time increases due to ambient pressure and the increase in simple reaction time is detectable in professional divers at 6.0 atm not at 1.9 atm abs. At the same time accuracy stays constant. We speculate that our findings are caused by nitrogen narcosis in some divers.

The effects of increased pressure, variation in inspired gases and the use of a mask during dry chamber dives on salivary cortisol in professional divers

INTRODUCTION

Stress activates the hypothalamic-pituitary-adrenal axis resulting in measurable changes in hormone levels in blood or saliva in humans. We aimed to find out if professional divers expressed any change in salivary cortisol levels during a simulated dive to 608 kPa (50 metres' sea water) in a hyperbaric chamber. Furthermore, we investigated the effect of wearing a mask or modifying the breathing gas during decompression.

METHODS

We investigated 89 Navy and Coast Guard male divers. The divers were randomised into three groups for decompression by inspired gas and the use of a mask. The saliva samples were collected before and approximately 3 minutes after the hyperbaric test.

RESULTS

Salivary cortisol levels decreased from a mean (SD) of 16.0 (8.1) mmol per L pre-dive to 10.3 (5.0) mmol per L post-dive (P < 0.01). Cortisol values did not relate to the anthropometric and physical fitness characteristics of the divers or to increased pressure, variation in inspired gases or the use of a mask. The individual variation in cortisol values was large.

CONCLUSIONS

This finding is in line with previous studies demonstrating large individual variations in salivary cortisol. Our findings suggest that professional divers are well adapted to these hyperbaric conditions. However, there continues to be a need to identify divers sensitive to stress caused by diving and the hyperbaric environment.

Psychosocial factors associated with suicidal ideation among young men exempted from compulsory military or civil service

AIMS

The aim of this study was to identify factors associated with suicidal ideation among young men exempted from compulsory military or civil service in Finland.

METHODS

The study involved a total of 356 men exempted from military or civil service. The research data were collected using questionnaires and register data.

RESULTS

One third of the young men exempted from compulsory military or civil service reported serious suicidal ideation. Of the men with serious suicidal ideation, one third had attempted suicide. Various childhood adversities and current stressful life events and problems were associated with suicidal ideation. Multivariate logistic regression analysis showed that the following factors were independently associated with suicidal ideation: maternal alcohol-related problems, changes in the family, discord with the boss over the past 12 months, and lack of social support. Accumulation of problems predicted suicidal ideation.

CONCLUSIONS

Men exempted from compulsory military or civil service comprise an important target group in the prevention of suicide. In order to prevent suicidal behaviour among young men at risk, it is important to address the significance of social support and relationships, and likewise to be aware of early risk indicators such as maternal alcohol-related problems.

Unaltered blood coagulation and platelet function in healthy subjects exposed to acute hypoxia

INTRODUCTION

Acute hypoxia has been suspected to cause blood coagulation and platelet activation. Our aim was to study blood coagulation and platelet function during a short hypoxic exposure.

METHODS

Healthy nonsmoking men (N = 10) inhaled a normobaric hypoxic gas mixture containing 8% of oxygen (92% nitrogen) for 7 min via a face mask. Venous blood was collected 5 min before and during the 5 to 7 min of hypoxia exposure (i.e., pretest and hypoxia samples, respectively) while monitoring arterial oxygen saturation (SaO2) with pulse oximetry. Blood sampling was completed in 2 min and the face mask was removed. Venous epinephrine and norepinephrine, complete blood counts, and a panel of coagulation markers were analyzed. Platelet aggregation induced by ristocetin, adenosine diphosphate (ADP), arachidonic acid, and thrombin receptor activating peptide was studied with Multiplate and shear force-dependent functions with PFA-100R (collagen/epinephrine and collagen/ADP cartridges), both assays in whole blood.

RESULTS

During hypoxia, SaO2 declined from 98 to 58% (ranges 97-99% vs. 42-85%), while heart rate increased from 69/min to 94/min (SD 11 vs. SD 13). Venous epinephrine and norepinephrine levels also increased. This short hypoxia induced minor but uniform increases in red cells, reticulocytes, and leukocytes and decreases in platelet counts. Plateletfunctions and prothrombin time, APTT, thrombin time, D-dimer, fibrinogen levels or von Willebrand factor (VWF), antithrombin, factor V (FV) or FVIII activities did not change.

DISCUSSION

Profound acute hypoxia failed to affect blood coagulation or platelet functions in healthy individuals.

[Motion sickness at sea and in the air]

Sea sickness was first described in 1881, and since then the syndrome has been described to be associated with travelling also in other means of transportation. Symptoms of motion sickness are quite common in otherwise healthy people. The symptoms are usually of short duration and last for not longer than three days. Children of 2 to 12 years are most susceptible. Women are more susceptible than men to motion sickness. Predisposing factors include menstruation and pregnancy. Scopolamine and antihistamines are used for prevention of motion sickness.

Young men exempted from compulsory military or civil service in Finland--a group of men in need of psychosocial support?

AIMS

The aim of this study was to find out whether young men exempted from compulsory military or civil service constitute a group of young men in need of psychosocial support from the social and health services.

METHODS

The study involved a total of 356 men exempted from military or civil service and 440 young men conscripted into service. The research data were collected using questionnaires and register data.

RESULTS

Men exempted from military or civil service differed from conscripts in terms of psychosocial well-being. Compared with conscripts, they had already been in a more disadvantaged position with regard to their childhood living conditions. As young adults, they had met with a greater number of mental and social problems than conscripts: alcohol-related problems, unemployment, financial problems, homelessness, lack of social support and psychological distress. Young men exempted from service typically suffered from an accumulation of problems. Diverse problems were common particularly among men who had interrupted their service. There was a moderate correlation between current and childhood adversities.

CONCLUSIONS

Men exempted from military or civil service comprise a group with a wide range of psychosocial problems and are a target group for supportive interventions. Special attention should be paid to the prevention of problems and promotion of well-being of men who interrupt their service. The accumulation of problems poses a challenge for the development of such interventions.

Psychosocial correlates of police-registered youth crime. A Finnish population-based study

This study is focused on psychosocial correlates of youth crime in a sample of 2330 Finnish boys born in 1981. Two kinds of data were combined: questionnaires completed by the boys at call-up in 1999 and crime registered in the Finnish National Police Register between 1998 and 2001. One-fifth of the boys were registered to offending during the 4-year period in late adolescence; 14% were registered for one or two offences, 4% for three to five offences, and 3% for more than five offences. Crime accumulated heavily in those with more than five offences, as they accounted for 68% of all crime. Independent correlates of crime were living in a small community, parents' low educational level and divorce, having a regular relationship, self-reported delinquency, daily smoking, and weekly drunkenness, whereas anxious-depressiveness was reversely associated with crime. Most psychosocial problems covaried linearly with offending frequency, being particularly manifested by multiple recidivists. However, recidivists had very rarely used mental health services. The results indicate that offending and various psychosocial problems accumulate in a small minority of boys not reached by mental health services.

Police-registered offenses and psychiatric disorders among young males : the Finnish "From a boy to a man" birth cohort study

OBJECTIVE

To study associations between crime and psychiatric disorders among adolescent males in a representative population-based cohort study.

METHOD

The sample includes 2,712 Finnish boys born in 1981. Information on criminality consists of offenses registered in the Finnish National Police Register 1998-2001. Crime was classified according to frequency and type (drug, violent, property, traffic, and drunk driving offenses). Information on psychiatric diagnoses between 1999 and 2004 was collected from the Finnish National Military Register.

RESULTS

Of the 2,712 boys, 22% had a crime registration during the 4-year period, and 10% had at least one psychiatric disorder according to the Military Register. Those with psychiatric disorders accounted for 49% of all crimes. Of those with more than five crimes (n = 98), 59% had psychiatric diagnoses. After adjusting for other crime types and childhood socio-economic status, property crime was independently associated with several diagnoses: antisocial personality (APD), substance use (SUD), psychotic, anxiety, and adjustment disorders. Drug offending was independently associated with APD, SUD, and psychotic disorder, and traffic offenses with APD.

CONCLUSIONS

Youth crime is predominantly associated with antisocial personality and substance use disorders. Crime prevention efforts should focus on boys showing a risk for antisocial and substance use problems. In particular, property, drug, and repeat offenders need mental health and substance use assessment. There is a need to develop integrated mental health and substance use treatment services for young offenders within or alongside the criminal justice system.

Childhood predictors of drunkenness in late adolescence among males: a 10-year population-based follow-up study

AIMS

To study childhood precursors of drunkenness frequency among 18-year-old boys in a representative, nation-wide 10-year follow-up study.

DESIGN

In 1989, a general population sample of 2,946 8-year-old boys was collected. Three different informant sources were used: parents, teachers and the boys themselves. The follow-up was 10 years later in 1999, when the boys were called up for their obligatory military service at age 18. Information about drunkenness frequency was obtained from 78.3% (n=2306) of the original sample.

SETTING

Finland, nation-wide; in 1989 at schools, in 1999 at the obligatory military call-up.

PARTICIPANTS

General population sample of Finnish boys born in 1981.

MEASUREMENTS

At age 8, the Rutter A2 scale, Rutter B2 scale and Child Depression Inventory (CDI) were used. At age 18, self-reported drunkenness frequency during the previous 6 months was determined.

FINDINGS

Of the subjects, 15.0% reported never being drunk from alcohol, 74.6% reported being occasionally drunk and 10.4% reported being drunk at least once a week during the previous 6 months. After adjusting for other variables, teacher's estimate of the child's problem behaviour at age 8 predicted frequent drunkenness in late adolescence. Hyperactive problems predicted both occasional and frequent drunkenness. Conduct problems at age 8 predicted only frequent drunkenness. High teacher-reported scores of emotional problems predicted lower occurrence of drunkenness-orientated alcohol use.

CONCLUSIONS

The educational system has a potential role in detecting boys at risk of later risk-taking behaviours, such as frequent drunkenness. Early interventions in children with conduct problems and hyperactivity are called for.

ADAPTIVE FUNCTIONING, PSYCHOPATHOLOGY AND SERVICE USE AMONG 18-YEAR-OLD BOYS WITH DRUNKENNESS-RELATED ALCOHOL USE

AIMS

To study the associations between drunkenness frequency and adaptive functioning, psychopathology and service use among 18-year-old Finnish boys in a nation-wide population-based study.

METHODS

Information about drunkenness frequency within the previous six months was collected from the Finnish boys born in 1981 (n = 2306) at the boys' obligatory military call-up in 1999. Self-report questionnaires were used to study demographic factors, adaptive functioning, risk behaviour, life events, and mental health service use. Psychopathology and adaptive functioning was assessed with the Young Adult Self-Report (YASR) questionnaire.

RESULTS

Of the boys, 85% reported drunkenness within the previous 6 months. Most of the subjects were occasionally drunk: 39% reported drunkenness less than a month, and 35% less than once a week, while 10% reported being frequently drunk once a week or more often. Occasional drunkenness was associated with better adaptive functioning and psychosocial well-being in general. Refraining from drunkenness was associated with suicidal ideation and internalizing problems in the YASR scale. Frequent drunkenness associated with daily smoking, illicit drug use, and externalizing problems in the YASR scale, especially delinquent behaviour. In the multivariate analysis, number of friends, having a regular relationship and cigarette smoking had a linear association with frequency of drunkenness, while drunkenness-related alcohol use was less common among those with poor friendship quality. Among the participants, entering substance use treatment was rare (0.2%). Frequent drunkenness was found to be common among mental health service users.

CONCLUSIONS

Among late-adolescent boys, occasional drunkenness is a normative alcohol use pattern and associates with social competence and good psychosocial functioning. Late-adolescent boys refraining from drunkenness in addition to those with frequent drunkenness may be in a need of mental health assessment. As entering substance use treatment is infrequent, establishing integrated services with multi-professional co-operation for late-adolescent males with frequent drunkenness is emphasized.

Factors associated with ideation and acts of deliberate self-harm among 18-year-old boys. A prospective 10-year follow-up study

BACKGROUND

The aims of the study were: (1) to identify the prevalence of ideation and acts of deliberate self-harm in 18-year-old boys; (2) to report the use of mental health services among these boys; (3) to identify risk factors assessed at age 8 and (4) to identify associated cross-sectional factors at age 18 of self-reported ideation and acts of deliberate self-harm.

METHODS

The participants in this community-based 10-year follow-up study consisted of 2,348 boys born during 1981. At baseline, three informant sources were used: parents, teachers and the children themselves. The questionnaires used were the Rutter Parents Scale, the Rutter Teacher Scale and the Children's Depressive Inventory. At follow-up, boys' psychopathology, adaptive functioning and substance use were studied using the Young Adult Self-Report questionnaire. Further questions about demographic factors and life events were added at both stages.

RESULTS

The prevalence of ideation of deliberate self-harm was 4.0%, and of acts 2.2%, during the preceding 6 months. Of the subjects who reported ideation, 9.7%, and of those who reported acts, 16.0%, had used mental health services during the previous year. Self-reported depressive symptoms at age 8 predicted ideation and acts of deliberate self-harm 10 years later. Suicidal boys' problems in many life areas were linked with suicidal tendency through psychiatric symptoms, especially anxious/depressed symptoms and aggressive behaviour.

CONCLUSIONS

The connection between self-reported depressive symptoms at age 8 and ideation and acts of deliberate self-harm at age 18 is a good reason to already pay special attention to children's own intimations of distress in elementary school. It is likely that an effective way to prevent suicidality among adolescents is to search for and treat psychiatric problems among young people. Self-reported screening questionnaires used, e.g. in school healthcare, may provide an opportunity to recognize these problems.

Recognition of psychiatric disorders, and self-perceived problems. A follow-up study from age 8 to age 18

OBJECTIVE

To study the rate of, and factors associated with, recognition of psychiatric disorders and self-perceived problems among 18-year-old adolescent boys.

METHOD

The study population consisted of 2347 Finnish boys born during 1981 attending military call-up (79.7% of the original sample). At age 8, the boys were evaluated by parental and teacher Rutter scales and by self-reports using the Child Depression Inventory (CDI). At military call-up 10 years later, the boys filled in the Young Adult Self-Report (YASR). Information about psychiatric disorders recognized at the military call-up health examination was obtained from the national military register.

RESULTS

About 4.6% of boys were recognized as having a psychiatric disorder at the military call-up medical examination. In addition, 23.1% of boys reported emotional, behavioral or relational difficulties but were not recognized as having an ICD 10 psychiatric diagnosis at the military call-up medical examination. A higher level of psychopathology, problems across different life domains and early onset of problems were more strongly associated with recognition of psychiatric disorder than with self-reports of difficulties without a recognized psychiatric disorder. All informant sources, parents, teachers and children themselves at age 8, independently predicted recognition of psychiatric disorders and perceived difficulties 10 years later.

CONCLUSIONS

Only a minority of adolescents with psychiatric problems are recognized as having a psychiatric disorder in the health services. Efforts to prevent psychiatric disturbance in early life are emphasized. The use of screening methods in school health settings to detect children in need of child mental health services is justified.

Childhood predictors of psychiatric disorders among boys: a prospective community-based follow-up study from age 8 years to early adulthood

OBJECTIVE

To study early childhood predictors for early adulthood psychiatric disorders.

METHOD

The sample included 2,712 Finnish boys born in 1981. Information about the 8-year-old boys' problem behavior was obtained from parents, teachers, and children. The 10-15-year follow-up information about psychiatric disorders in early adulthood was based on the national military register between the years 1999 and 2004.

RESULTS

According to the military register, 10.4% of men had a psychiatric disorder. All informant sources, parents, teachers, and the children themselves predicted early adulthood psychiatric disorders. Conduct symptoms at age 8 independently predicted substance abuse, antisocial personality, and psychotic disorders in early adulthood. Self-reported depressive symptoms, poor school performance, and living in a nonintact family had an independent predictive association with antisocial personality and depressive disorders. Parent-reported emotional symptoms and self-reported psychosomatic symptoms independently predicted anxiety disorders. About one third of those who had used services at age 8 had a psychiatric disorder in early adulthood. Among service users, conduct and hyperkinetic symptoms predicted psychiatric disorders in early adulthood.

CONCLUSIONS

Efforts to prevent early adult psychiatric disturbance already present in childhood are emphasized. Active screening to detect children in need of early interventions in childhood to prevent negative development in early adulthood is justified.

Military fitness class of Finnish 18-year-old men--prediction of military fitness class at call-up with the YASR and sociodemographic factors

OBJECTIVE

The aim of this study was to examine psychosocial factors associated with military fitness class, classified as capability of service, vs. temporary or permanent exemption from service.

METHOD

Participants were 2,340 (80% of the original sample) Finnish 18-year-old men at call-up for obligatory military service who filled in the Young Adult Self-Report (YASR) questionnaire.

RESULTS

Temporary exemption from military service was independently associated with the YASR total problem score, externalizing and internalizing problems, excessive alcohol use, drug use, problems with peers and family, and mental health service use. Permanent exemption was independently associated with problems with peers and family.

CONCLUSION

The YASR is a potential selection tool to be used at call-up. Temporary exemption was more strongly associated with psychosocial problems than permanent exemption. Because of the high level of psychological problems among those temporarily exempted, the call-up situation offers a unique opportunity to identify those with problem behaviour and risk of marginalization.

Sense of coherence among Finnish young men--a cross-sectional study at military call-up

The aim of this study was to study associations between sense of coherence (based on Antonovsky's theory), and mental health problems, the use of mental health services, substance use, predisposition to suicide and possible psychiatric diagnosis among Finnish young men. The study included 2314 18-year-old young men who attended military call-up in autumn 1999 and completed the 13-item Orientation to Life Questionnaire (SOC-13) questionnaire (89.1% of the study sample attending military call-up). Furthermore, all young men had a medical examination at military call-up, including evaluation of possible psychiatric disorder. Suicidality, perceived mental health problems, psychiatric diagnosis at military call-up medical examination, use of mental health services, excessive alcohol consumption and use of illicit drugs were identified as independent factors associated with sense of coherence. Sense of coherence is a valuable construction in psychiatric evaluation of adolescents. SOC-13 can be used both in clinical practice and in epidemiological research to evaluate the adolescent's health resources. Future research on its applications in clinical practice is warranted.

Factors associated with depressive symptoms among 18-year-old boys: a prospective 10-year follow-up study

BACKGROUND

The aim is to study associative and predictive factors for self-reported depressive symptoms among 18-year-old boys.

METHODS

The participants in this community-based 10-year follow-up study consisted of 2348 boys born during 1981. At baseline, three informant sources were used: parents, teachers, and the children themselves. At follow-up, self-report questionnaires were used to study boys' family factors, life events, adaptive functioning, and substance use. Depressive symptoms at age 18 were established using Beck's Depression Inventory (BDI).

RESULTS

Poor adaptive functioning within family and in education, having fewer than two close friends, somatic health problems, and using illicit drugs were all independently associated with a high level of depressive symptoms in the cross-sectional data at age 18. Self-reported depressive symptoms (Children's Depression Inventory, CDI) at age 8 independently predicted an increased number of depressive symptoms 10 years later.

LIMITATIONS

Only self-reported questionnaires were used at follow-up.

CONCLUSIONS

The high association between depressive symptoms at age 8 and at age 18 gives grounds for paying special attention to children's own intimations of distress already in the early school years. Using self-report screening questionnaires in school health care may help identify children's depressive symptoms.

Mental health service use among 18-year-old adolescent boys: a prospective 10-year follow-up study

OBJECTIVE

To study prevalence and factors associated with mental health service use among 18-year-old adolescent boys.

METHOD

Predictors at age 8 and factors at age 18 associated with mental health service use during the preceding 12 months were studied in a general population sample of 2,316 Finnish boys born in 1981 attending military call-up (79% of the original sample).

RESULTS

Within the preceding 12 months, 2.1% of the boys had used mental health services. At age 18, internalizing, anxious-depressive, and withdrawal symptoms; health problems; not living with parents; use of illicit drugs; high level of alcohol use; and regular smoking were independently associated with service use. At age 8, a high level of emotional and behavioral symptoms, need for referral, and low school performance according to teacher evaluations predicted service use 10 years later.

CONCLUSIONS

Only a minority of adolescents with severe problems had used mental health services. Because of the wide range of problems and comorbidity among service users, there is a need for integration of different services. Education services have a central role in the early detection of those who will later use mental health services.

Anatomy of the Achilles tendon (tendo calcaneus) with respect to tendon thickness measurements

267 normal controls of different ages underwent achilles tendon thickness measurements by ultrasonography (US) for reference. 96 recruits and 10 young women additionally underwent magnetic resonance imaging of the achilles tendons and calves for more systematic evaluation of the factors influencing tendon thickness. Children under 10 had a tendon thickness (mean +/- SD) of 4.6 +/- 0.8 mm, 10-17 year-olds 6.1 +/- 0.8 mm, 18-30 year-olds 6.3 +/- 0.5 mm and over 30 year-olds 6.9 +/- 1.0 mm. Women had slightly thinner tendons than men, but the difference was statistically significant only in the oldest age group. Normal variation in shape of the tendon caused up to a 25% variation in the measured thickness values. In the large sample of recruits a statistically significant correlation was found between the tendon thickness and body height. Differences in population height could account for the measured differences in normal achilles tendon thickness found in studies on Japanese subjects compared with studies on European and American subjects.