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of cardiac risk among profe ssional drivers. Scand J Work Environ Health 1994;20:73-86.This literature review indicates that professional drivers have excess cardiac risk that is not fully explained by standard risk factors. The contributi on of occupation is suggested by two independent methods and by psychophysiological studies during on-the-job driving. Driving has been conceptualized as a threat-avoidance task. Stimuli encountered in traffic are not inherently aversive but become so by association with driving experie nce, a formulation corroborated by laboratory studies in which stimuli such as car headlights elicit cardiovascular hyperreactivity and electroencephalographic signs of arousal in professional drivers. More-advanced neurophysiological methods (event-related potentials) show higher cortical electrone gativity to imperative signals among professional drivers than among nondriver referents. These data are viewed in light of reports of possible associations between event-related slow potentials and cardiac risk. A clinically and ecologically relevant neurocardiological model is proposed, and preventive strategies, including workplace interventions, are suggested.K EY TERMScardiova scular disease, event-related potentials, glare, neurocardiology, professional drivers, review, work stress.Of the numerous studies performed in va rious countries on cardiovascular disease and professional driving over a sp an of almost three de cades, ne arly all have shown an exce ss ri sk of cardiovascular di sease among professional drivers. Despite rigorous se lection against these disorders at hiring and during periodic medical foll ow-up ( 1-4), a risk of hyp ertension, ventri cu lar arrhythmias, myocardial infarction, and other ischemic heart disease ha s been ob served in 28 of the 32 reports found to consider thi s question (1-32). (No ns ig nifica nt findings have be en reported in references 13, 18, 19, and 23.) Of particular note in many of these studies is the close relation between the number of work years as a driver and the untowardly yo ung ag e at which these ev e nts occur (l , 5, 7, 9 17, 26, 29, 32). For example, in studies of young myocardial infarct ion patients, fo r whom profession was determined, an unexpectedly high percentage (up to 40 %) comprised professional dri vers (9,17,26,29,32). While standard ri sk-factor status tends to be high in thi s population, these fa ctors have not been clearly shown to distinguish professional drivers from other lo wer ri sk groups (1 , 15, 16,33-35) (tab le I). Rece ntly , Ro sengren and her co-workers (27) demonstrated that the excess risk of coronary he art disease among middle-aged bus and tram drivers occurred independently of sta ndard ri sk-factor status .Thus the quest ion ari ses as to how this excess cardiac risk oc curs for professional drivers. A growing co nse ns us indicates that occupational factors must be gi ven ca reful consideration (1-3). A focus on neural mech anisms pr omises to offer meaningful insig hts into the problem (3,36,37). In...

Somatosensory evoked potential (SEP) changes associated with selective attention were investigated. In 16 subjects, SEPs were recorded from five locations while they counted electrical stimuli to one of four randomly stimulated fingers. Sequential SEP events measured included peaks P30 (positivity at 30 msec). P45, N60, P100. N140. P190. N230, P400. Counting was associated with greater P45, P100. P190, N230, and P400 amplitudes; effects were not attributable to eye or tongue activity. Analyses designed to reveal changes associated with two conceptualized “channels” (finger class, hand) showed that the P45, P100, and P190 amplitude increases involved both channels. The P400 effect was limited to the target finger. Channel effects for N60 and N140 amplitudes resulted from decreases localized to the unattended element of one channel, suggesting “inhibition.” Latency effects involved mainly the hand channel; counted hand latencies were shorter for P30, P45, P100 and P190. The findings indicate modifications of both early and late electrocortical events with selective attention, and that changes can be of several kinds. They support the view that attention proceeds in more than one stage.

Patterns of electroencephalographic (EEG) and polygraphically recorded cardiovascular (CV) reactivity to the glare pressor test (GPT) were compared in 19 healthy, young male professional drivers and eight non-driver controls. After the first headlight impulse, 15 drivers showed persistent blockade of spontaneous alpha activity or complete desynchronization. This was accompanied by a significant fall in digital pulse amplitude and a significant rise in diastolic blood pressure (BP) (7.3 +/- 9.5 mmHg). Most drivers recovered baseline alpha activity and showed milder diastolic BP and digital pulse changes after the final (5th) glare impulse. However, in two drivers this last glare stimulus elicited the most pronounced changes: in one case a rapid onset of ventricular extrasystoles and in the other, maximal rise in diastolic BP, together with a persistently desynchronized EEG. No significant effects of the GPT upon central and CV indices were found in the control group. These results indicate that drivers show cardiovascular hyperreactivity to the GPT, with strong central arousal as expected during night driving when an on-coming headlight can represent impending danger and the need for accurate and timely responses to avoid a collision. Once optimal stimulus parameters for routine application are determined, the glare pressor test with EEG and polygraphic recording will offer a clinically useful, standardizable method for evaluating the connection between central mechanisms and CV reactivity in professional drivers, a cohort of patients whose occupational activity epitomizes mentally stressful work, and who are at high cardiac risk.