Interaction between parental psychosis and early motor development and the risk of schizophrenia in a general population birth cohort.

BACKGROUND: Delayed motor development in infancy and family history of psychosis are both associated with increased risk of schizophrenia, but their interaction is largely unstudied. AIM: To investigate the association of the age of achieving motor milestones and parental psychosis and their interaction in respect to risk of schizophrenia. METHODS: We used data from the general population-based prospective Northern Finland Birth Cohort 1966 (n=10,283). Developmental information of the cohort members was gathered during regular visits to Finnish child welfare clinics. Several registers were used to determine the diagnosis of schizophrenia among the cohort members and psychosis among the parents. Altogether 152 (1.5%) individuals had schizophrenia by the age of 46 years, with 23 (15.1%) of them having a parent with psychosis. Cox regression analysis was used in analyses. RESULTS: Parental psychosis was associated (P<0.05) with later achievement of holding the head up, grabbing an object, and walking without support. In the parental psychosis group, the risk for schizophrenia was increased if holding the head up (hazard ratio [HR]: 2.46; degrees of freedom [df]=1; 95% confidence interval [95% CI]: 1.07-5.66) and touching the thumb with the index finger (HR: 1.84; df=1; 95% CI: 1.11-3.06) was later. In the group without parental psychosis, a delay in the following milestones increased the risk of schizophrenia: standing without support and walking without support. Parental psychosis had an interaction with delayed touching thumb with index finger (HR: 1.87; df=1; 95% CI: 1.08-3.25) when risk of schizophrenia was investigated. CONCLUSIONS: Parental psychosis was associated with achieving motor milestones later in infancy, particularly the milestones that appear early in a child's life. Parental psychosis and touching the thumb with the index finger had a significant interaction on risk of schizophrenia. Genetic risk for psychosis may interact with delayed development to raise future risk of schizophrenia, or delayed development may be a marker of other risk processes that interact with genetic liability to cause later schizophrenia.

Interaction between parental psychosis and risk factors during pregnancy and birth for schizophrenia - the Northern Finland 1966 Birth Cohort study.

Our aim was to investigate the association between parental psychosis and potential risk factors for schizophrenia and their interaction. We evaluated whether the factors during pregnancy and birth have a different effect among subjects with and without a history of parental psychosis and whether parental psychosis may even explain their effects on the risk of schizophrenia. The sample comprised 10,526 individuals from the Northern Finland 1966 Birth Cohort. A total of 150 (1.4%) cohort members had schizophrenia by the age of 44 years, of them 18 (12.0%) had a parent with a history of psychosis. In non-psychotic cohort members, this figure was 495 (4.8%). In the parental psychosis group, significant early biological risk factors for schizophrenia included high birth weight (hazard ratio, HR 11.4; 95% confidence interval 3.3-39.7) and length (HR 4.1; 1.3-12.5), high birth weight in relation to gestational age (HR 3.2; 1.1-9.0), and high maternal age (HR 2.6.; 1.0-6.7). High birth weight and length and high maternal education had a significant interaction with parental psychosis. The presence of any biological risk factor increased the risk of schizophrenia significantly only among the parental psychosis group (HR 4.0; 1.5-10.5), whereas the presence of any psychosocial risk factor had no interaction with parental psychosis. Parental psychosis can act as an effect modifier on early risk factors for schizophrenia. Evaluation of the mechanisms behind the risk factors should, therefore, include consideration of the parental history of psychosis.

Effects of acoustic environment on work in private office rooms and open-plan offices - longitudinal study during relocation.

The aim was to determine how the perceived work environment, especially acoustic environment, and its effects differed in private office rooms and in open-plan offices. The subjects consisted of 31 workers who moved from private office rooms to open-plan offices and who answered the questionnaire before and after the relocation. Private office rooms were occupied only by one person while open-plan offices were occupied by more than 20 persons. Room acoustical descriptors showed a significant reduction in speech privacy after relocation. The noise level averaged over the whole work day did not change but the variability of noise level reduced significantly. Negative effects of acoustic environment increased significantly, including increased distraction, reduced privacy, increased concentration difficulties and increased use of coping strategies. Self-rated loss of work performance because of noise doubled. Cognitively demanding work and phone conversations were most distracted by noise. The benefits that are often associated with open-plan offices did not appear: cooperation became less pleasant and direct and information flow did not change. Nowadays, most office workers, independent of job type, are located in open-plan offices without the individual needs of privacy, concentration and interaction being analysed. This intervention study consisted of professional workers. Their work tasks mainly required individual efforts, and interaction between other workers was not of primary concern, although necessary. The results suggest that the open-plan office is not recommended for professional workers. Similar intervention studies should also be made for other job types.

Performance effects and subjective disturbance of speech in acoustically different office types--a laboratory experiment.

UNLABELLED: This study examined how the intelligibility of irrelevant speech, determined with the Speech Transmission Index (STI), affects demanding cognitive task performance. Experiment was carried out in a laboratory that resembled an open-plan office. Three speech conditions were tested corresponding to a private office (STI = 0.10), an acoustically excellent open office (STI = 0.35) and an acoustically poor open office (STI = 0.65). All conditions were presented at equal level, 48 dBA. The STI was adjusted by the relative levels of speech and masking sound. Thirty-seven students participated in the experiment that lasted for 4 h. All participants performed five tasks in each of the three speech conditions. Questionnaires were used to assess subjective perceptions of the speech conditions. Performance in the operation span task, the serial recall and the activation of prior knowledge from long-term memory were deteriorated in the speech condition with the highest speech intelligibility (STI = 0.65) in comparison with the other two conditions (STI = 0.10 and STI = 0.35). Unlike performance measures, questionnaire results showed consistent differences among all three speech conditions, i.e. subjective disturbance increased with ascending speech intelligibility. Thus, subjective comfort was disturbed more easily than performance. The results support the use of STI as an essential room acoustic design measure in open-plan offices. PRACTICAL IMPLICATIONS: Reduction of speech intelligibility in office environments by proper acoustic design would be beneficial in terms of both work performance and subjective comfort. Proper acoustic design requires both the use of high acoustic absorption and an appropriate masking sound.

The effect of speech and speech intelligibility on task performance.

The aim of this study was to find out what are the effects of three different sound environments on performance of cognitive tasks of varying complexity. These three sound environments were 'speech', 'masked speech' and 'continuous noise'. They corresponded to poor, acceptable and perfect acoustical privacy in an open-plan office, respectively. The speech transmission indices were 0.00, 0.30 and 0.80, respectively. Sounds environments were presented at 48 dBA. The laboratory experiment on 36 subjects lasted for 4 h for each subject. Proofreading performance deteriorated in the 'speech' (p < 0.05) compared to the other two sound environments. Reading comprehension and computer-based tasks (simple and complex reaction time, subtraction, proposition, Stroop and vigilance) remained unaffected. Subjects assessed the 'speech' as the most disturbing, most disadvantageous and least pleasant environment (p < 0.01). 'Continuous noise' annoyed the least. Subjective arousal was highest in 'masked speech' and lowest in 'continuous noise' (p < 0.05). Performance in real open-plan offices could be improved by reducing speech intelligibility, e.g. by attenuating speech level and using an appropriate masking environment.

Driving circumstances and accidents among novice drivers.

OBJECTIVE: The study evaluated the accident risk of certain driving circumstances and driving motives among novice drivers. METHODS: Self-reported exposure and accidents according to driving circumstances and driving motives were compared between young (n = 6,847) and middle-aged (n = 942) male and female novice drivers. For young drivers, self-reported accidents were further compared to fatal accidents (n = 645) in terms of the driving conditions in which they occurred. The survey was conducted in 2002 and the questions regarding the quantity and quality of driving exposure and accidents covered the first four years of the novice drivers' driving career after licensing. Data on fatal accidents related to the period of 1990 to 2000. RESULTS: Leisure-time driving, driving just for fun, and driving with passengers and during evenings and at night was more typical for young drivers than for middle-aged drivers. For middle-aged drivers, the most typical driving was driving to or from work. Driving on errands was more typical for females than males. Nighttime driving was overrepresented in young drivers' self-reported and fatal accidents, compared to the share of young drivers' driving at night. Slippery road conditions were over-represented in young male drivers' self-reported accidents, but not in their fatal accidents, whereas for young females slippery road conditions seemed to increase the propensity of fatal accidents. CONCLUSIONS: The study concluded that some driving conditions increase the risk of certain types of accidents among certain driver groups, but not among all drivers. For example, slippery road conditions were overrepresented in young male drivers' minor (self-reported) accidents, but not in their fatal accidents. For young female drivers slippery road conditions seem to increase the propensity of fatal accidents. Driving circumstances are different in minor (self-reported) and fatal accidents. When drawing conclusions regarding accident risk, it is important to determine the seriousness of the accidents which take place.

Microanatomical characteristics of marginal ommatidia in three different size-classes of the semi-terrestrial isopod Ligia exotica (Crustacea / Isopoda)

The aims of this paper have been (a) to characterize marginal ommatidia from different eye regions through a detailed description of their distinct ultrastructural features in three different size-classes of L. exotica, and (b) to compare microanatomical characteristics of the marginal ommatidia with those of ommatidia of the same eye, but located further centrally. On the basis of transverse as well as longitudinal sections we conclude that new ommatidia are added from a crescentic dorso-anterio-ventral edge of the eye and that maturing ommatidia go through a sequence in which originally the nuclei of cone-, pigment-, and retinula cells are arranged in three separate layers. At the beginning of the microvillar development, the organization of the corresponding rhabdomeres is still quite different (much less regular) from that of those rhabdomeres that make up the mature rhabdom. Marginal ommatidia always possess smaller diameters than more centrally located ones and retinal screening pigment granules are most apparent in the retinula cells only after the first microvilli have appeared. The diameters of rhabdom microvilli (approx. 55 nm) do not differ in ommatidia from the five investigated eye regions in small specimens (< 1.5 cm body length), but show a tendency to be slightly wider in the anterior (= frontal or rostral) regions of the eye (approx. 65 nm) in larger specimens (> 2.0 cm body length).

Microanatomical characteristics of marginal ommatidia in three different size-classes of the semi-terrestrial isopod Ligia exotica (Crustacea / Isopoda)

The aims of this paper have been (a) to characterize marginal ommatidia from different eye regions through a detailed description of their distinct ultrastructural features in three different size-classes of L. exotica, and (b) to compare microanatomical characteristics of the marginal ommatidia with those of ommatidia of the same eye, but located further centrally. On the basis of transverse as well as longitudinal sections we conclude that new ommatidia are added from a crescentic dorso-anterio-ventral edge of the eye and that maturing ommatidia go through a sequence in which originally the nuclei of cone-, pigment-, and retinula cells are arranged in three separate layers. At the beginning of the microvillar development, the organization of the corresponding rhabdomeres is still quite different (much less regular) from that of those rhabdomeres that make up the mature rhabdom. Marginal ommatidia always possess smaller diameters than more centrally located ones and retinal screening pigment granules are most apparent in the retinula cells only after the first microvilli have appeared. The diameters of rhabdom microvilli (approx. 55 nm) do not differ in ommatidia from the five investigated eye regions in small specimens (< 1.5 cm body length), but show a tendency to be slightly wider in the anterior (= frontal or rostral) regions of the eye (approx. 65 nm) in larger specimens (> 2.0 cm body length). (AU)

Novice drivers' accidents and violations--a failure on higher or lower hierarchical levels of driving behaviour.

The study compared accident and offence rates of 28 500 novice drivers in Finland. The purpose was to study differences in accident and offence rates between male and female novice drivers of different age. The drivers reported in a mailed questionnaire, how many accidents they had been involved in and how much they had driven during their whole driving career. All the drivers had a driving experience of 6-18 months. Information about offences for a 2-year period was obtained from an official register of drivers' licences. The drivers were classified into three age brackets: 18-20, 21-30 and 31-50 years. The effect of driving experience was controlled by dividing the drivers into different mileage brackets. The data was analysed and the results were discussed in the framework of the hierarchical model of driving behaviour. Young novice drivers and especially young male drivers showed more problems connected to the higher hierarchical levels of driving behaviour than middle-aged novice drivers. The number of accidents and offences was highest among the young males and their accidents took place more often at night than female or older drivers' accidents. Female drivers showed more problems connected to the lower hierarchical levels of driving behaviour, e.g. problems in vehicle handling skills. Ways of measuring accident risk of different driver groups were also discussed, as well as the usefulness and reliability of self-reports in accident studies.

Self-destruction in Finnish motor traffic accidents in 1974-1992.

To find out the prevalence of suicides and other types of self-destructive behaviour in fatal motor traffic accidents in Finland, all the data on fatal accidents compiled by road accident investigation teams in the years 1987-1988 and 1991-1992 were investigated. The results were compared to an earlier study covering the years 1974-1975 and 1984-1985. The two 4-year periods covered a total of 2440 cases, which were classified into four groups: suicides, unclears, negligents and 'true' accidents. During the studied, nearly 20-year period, the number of suicides and negligent drivers had increased significantly. Also the relative proportion of suicides had increased from 1.1% to 7.4% and the relative proportion of negligents from 11.2% to 20.0%. There were no significant changes in the number of unclear cases. Suicide and unclear cases were similar to each other in many respects, whereas the negligent cases differed from these two. Most of the drivers were males in each of the three groups. Single-vehicle accidents were typical in the negligent group and collisions in the other groups. The drivers in the negligent group were younger than the drivers in the suicide and unclear groups. At the time of the accident, the most common mental state among suicide drivers was 'depression'.

Older drivers fail in intersections: speed discrepancies between older and younger male drivers.

A high percentage of older drivers' accidents occur in intersections when entering the traffic or crossing a main road. The problems may be in perception or attention, motor performance or inadequate interaction with other road users. Attempts to explain older drivers' problems have mostly focused on the properties and behaviour of the older drivers only, without considering the interaction between older and younger road users. The descriptions of older drivers' problems in intersections are usually based on accident data. This study aimed to describe the normal behaviour of older drivers, including driving habits, attention patterns and interaction with younger drivers. The driving behaviour of young, old and middle-aged male drivers was studied using video cameras and observers in three T-shaped intersections in Sendai, Japan. The results showed no differences in attention behaviour between the age groups as measured with head movements. The age groups had different acceleration habits and thus different turning time, which also varied depending on whether the vehicle on the main road came from the left or the right. Also the outcome of the turning manoeuvre was dependent on age. The time margins to the vehicles on the main road were shortest when an old driver was turning and a young driver approached on the main road. The time margin between the turning driver and the vehicle approaching on the main road was clearly shorter when the latter vehicle was a motorcycle than if it was a car. The results are discussed in relation to the literature on the risk behaviour of old drivers.

Differences in fatal loss-of-control accidents between young male and female drivers.

The study describes some factors behind fatal loss-of-control accidents of young male and female drivers. These loss-of-control accidents were compared to accidents in which the driver did not lose control of the car. The data comprised all fatal car accidents of young (18-21 years old) drivers in Finland during the years 1978-1991. Only culpable drivers were included in the analysis (the number of accidents studied was 338 for males and 75 for females). All these accidents were investigated by the Road Accident Investigation Teams in Finland and the original team reports were used. The results showed that equal proportions of all male and female drivers' accidents were loss-of-control accidents. However, when male drivers lost control of their car, it usually led to a single-vehicle accident, but for female drivers the loss of control usually resulted in a collision with another car. Male drivers drove too fast and under the influence of alcohol more often in loss-of-control accidents than in other types of accidents. Typically the male drivers' loss of control accidents took place during evenings and nights. The female drivers' loss-of-control accidents usually took place in slippery road conditions. This study concludes that risky driving habits play a bigger role in male drivers' loss-of-control accidents than in male drivers' no loss-of-control accidents or in any kind of female drivers' accidents. Lack of vehicle handling skills may be crucial in female drivers' loss-of-control accidents. Advantages of studying loss-of-control accidents instead of single-vehicle accidents are discussed.

Conflicting goals of skid training.

Efforts to make novice drivers drive more safely on slippery roads by means of special courses have mainly failed. In order to understand why the courses have failed, the views of instructors and students on the goals of skid training courses were compared. The importance given to anticipating vs manoeuvring skills was analysed. After completing a skid training course, students in four Nordic countries (Denmark, Finland, Norway and Sweden) assessed manoeuvring skills to be equally important to anticipating skills in the courses. However, instructors assessed anticipating skills to be more important than manoeuvring skills. The differences between the assessments of instructors and students were the same in all four countries. Manoeuvring exercises are widely used in the courses although the main purpose of these courses is to develop anticipating skills. The exercises may give students the impression that manoeuvring skills are more important than anticipating skills. Manoeuvring exercises also increase their self-confidence and may lead to underestimation of the risks involved, resulting in e.g. driving at higher speed.

Self-reported hostility and suicidal acts, accidents, and accidental deaths: a prospective study of 21,443 adults aged 25 to 59.

The association of self-reported hostility with morbidity and mortality due to external causes, including suicidal acts, was analyzed in 10,586 Finnish men and 10,857 Finnish women aged 24 to 59 years. Hostility was assessed from self-ratings on irritability, ease of anger-arousal, and argumentativeness. Three groups, low (33.6% of subjects), intermediate (50.6%), and extreme (15.9%), were formed from the self-reported hostility scores. A 6-year mortality follow-up yielded 76 violent deaths among men and 11 among women. A 4-year morbidity follow-up found 399 hospitalizations due to external causes among men and 169 among women. Among men, the risk ratio between the highest and lowest hostility groups was 1.51 (95% confidence interval, 1.16-1.96) for all events due to external causes and 3.6 (95% confidence interval, 1.63-7.89) for suicidal behavior, when effects of age, marital status, social status, and self-reported alcohol use were controlled in a multivariate model. No association was observed between traffic-related injuries and hostility. Hostility did not predict accidents or accidental deaths or suicidal behavior among women.

Individual alcohol reaction profiles.

The purpose of this study was to evaluate interindividual variation in acute reactions to ethanol. Six young, healthy female subjects participated in a double-blind experiment consisting of two identical alcohol sessions and one control session where glucose was infused instead of ethanol. Alcohol was infused in a standardized way to reach blood alcohol concentration of 1 mg/ml in 1 hr. During the 4 hr-sessions EEG-spectra, smooth pursuit eye movements, various mood variables, BAC and breath alcohol concentrations were studied repeatedly. The results showed that the subjects had a rather repeatable, individual reaction profile as expressed by changes in alpha mean frequency, theta band power, amount of corrective eye movements and subjective intoxication. The sensitivity of the subject to ethanol should thus be expressed as a reaction profile rather than as a change in a single variable.

Heart rate variability, cardiac mechanics, and subjectively evaluated stress during simulator flight.

The effects of a simulator flight task on the heart rate variation (HRV) and hemodynamic variables were studied in nine pilots with instrument flight ratings. An electrocardiogram (ECG), phonocardiogram (PCG), and impedance cardiogram (ICG) were recorded continuously during three successive flights. Indices of HRV, power spectra, and autocorrelograms were computed from the R-R interval signal. Stroke volume (SV), cardiac output (CO), and systolic time intervals (STI) were determined by means of the ECG, PCG, and ICG. A scaling method for a subjective evaluation of tiredness, effort, and success during the flight was used. The repeats of the flight task decreased the heart rate (HR), CO, and cardiac index (CI). The different phases of the flight altered the HR (mean 97 min-1, S.E.M. 4 min-1), total HRV (RMSM) (mean 33 ms, S.E.M. 5 ms), and the periodic HRV. Subjectively, the pilots felt only moderate stress. The subjectively evaluated tiredness was significantly associated with the STI. Moderate informative stress in the flight simulator affected the chronotropic parameters of the heart. The inotropic state of the heart was not affected by the different phases of the flight but possibly by the diminishing sympathetic drive with accommodation during the repeats.

Acute effects of intravenously given alcohol on saccadic eye movements and subjective evaluations of intoxication.

Effects of intravenously given alcohol on eye movements were analysed in ten voluntary subjects. Each subject served as his/her own control. Good correlations were found between the changes in saccade variables and subjective evaluations of alertness, eye movement control and intoxication. Interindividually, the subjective evaluation of drunkenness correlates with the alcohol effect on saccade variables better than do the other subjective variables or blood or breath alcohol concentrations. A steady decrease of mean and maximum velocity and a steady increase in the duration of saccades was observed during the alcohol infusion. The latency of saccades also increased. There was, however, a slight decrease of latency due to alcohol 15 min after the start of infusion, suggesting a biphasic effect of alcohol on saccade latency.