Aim

Search strategy

Three electronic databases (CINAHL, PSYCHINFO, EMBASE) were used to identify articles from inception to 10th May, 2016. Extensive search terms were identified and used to reduce the risk of missing relevant studies. Search terms included: automobile driv*, driv* ability, driv* competence, driv* perform*, driv* skill, fit*to driv*, AND affective, alcohol abus*, alcohol dependence, alcohol misuse*, alcohol use*, anxiet*, anxious, bipolar disorder, delusion, depress*, drug abus*, drug dependence, drug misuse, drug use*, mania, manic, mental disab*, mental disorder*, mental health, mental ill* disab*, mental ill*, mental* health disorder, mood, neuroses, neurosis, neurotic, obsessive* compulsive, OCD, panic, personality disorder*, phobia, psychiatric, psychiatry, psychology*, psychos*, psychotic, schizophreni*, schizotyp*, somatic, somatoform, stress, substance abus*, substance dependence, substance misuse, substance related disorder*, substance use*, and suicid*. The Search terms ‘antidepressant’, ‘anxiolytic’, ‘antipsychotic’ and ‘mood-stabilizer’ were also exploded and used to search for relevant studies. Citations of retrieved studies were exported into EndNote version ×7, and duplicate studies deleted. Reference lists of included articles were subsequently checked for additional articles of interest, and keywords searched on journal articles to obtain relevant studies.

Inclusion/exclusion criteria

Two authors (CU and MS) independently screened titles and abstracts of all identified studies, and excluded ineligible studies against the inclusion/exclusion criteria. Disagreements among authors were resolved by discussion and achieving consensus. Full copies of studies were obtained to determine eligibility of articles that were hard to identify solely based on titles and abstracts.

Quality assessment/evidence based ratings

Data extraction

Data were synthesised qualitatively, by using a narrative analysis. This method of analysis involved coding information from within individual studies and grouping them into like categories, based on the data provided and the findings of the analysis. Where there was over-lap in information and a study could potentially have been included under more than one of the categories, the study was allocated to the category for which the most data had been provided. Two authors (CU and MS) independently completed data extraction. Publication details, aims of the study, participant details, study design and findings related to the assessment of fitness-to-drive were extracted, summarised and presented in a table format.

Factors impacting on the ability to drive safely among people with mental health conditions.

For those with major depressive disorder, Bulmash et al. [8] found that people with depression, even when not on anti-depression medication, experienced higher levels of sleepiness when driving. This was found to impact their capacity to maintain appropriate speed when driving in a simulator. In addition, it was found that people with depression showed a significantly slower steering reaction time, and a greater number of crashes, as compared to controls. The level of slowed reaction time was not related to the level of severity of symptoms. When not sleepy, road position, speed and speed deviation were no different to those of controls. The association with depression was therefore apparent, even when participants were not on medication, and seemed to manifest itself when sleepiness was experienced in this study.

For those with bi-polar disorder who had committed driving offences, Zingg, Puelschen, and Soyka [41] found that drivers had impairments in problem solving and cognitive flexibility, alertness, and visual scanning/reaction time. It was noted that these signs and symptoms may have been caused by the clinical condition itself, or by medication taken for the condition in this study. Additionally, although information processing ability was found to be impaired in those with bi-polar disorder, this was no more so than in those who had committed driving offences, and who did not have a psychiatric condition. From this study it was suggested that a bi-polar disorder did not appear to have impaired information processing ability specifically. Decrements in psychomotor skill were also reported among people with schizophrenia by Segmiller et al. [40]. However, they demonstrated that reduced skill was not related to medication side effects.

For those in manic and hypomanic states, McNamara and Buckley [38] found that some participants reported speeding, making poor decisions, losing the feeling of control, decreased concentration and judgement, and impulsivity. As some participants reported that they felt their medical condition did not impair their driving ability, as compared with the general population, lack of insight among participants was also apparent in this study. Although participants reported that having an open communication with health professionals about their driving was helpful, they perceived fitness-to-drive guidelines as discriminatory. The underlying signs of grandeur and lack of insight characteristic of hypomanic and manic states among these participants would fit with this lack of capacity to recognise the gravity of risk to themselves and others, and the potential to feel the guidelines were not respectful of their standing.

In the most recent study by Brunnauer et al. [36], the authors explored the impact of mental illness on driving licence possession and driving restrictions. Higher educational status and being partnered or in a relationship was a key predictor for having a driving licence. People with mental health conditions were also found to be less likely to hold a driving licence or to be currently driving, as compared with controls, particularly for those with organic mental and psychotic disorders.

Capability and perception of health professionals assessing fitness-to-drive of people with mental health conditions

As can be seen in Table 3, Subgroup 2, the majority of studies examining health professionals’ assessment of fitness-to-drive were conducted in Canada, with the remaining few studies being conducted in the Republic of Ireland. The studies examined attention to the mental health condition and its impact on fitness-to-drive, and the nature and occurrence of recording of such factors in the medical notes. Variations in differing health professionals’ foci of interest were also investigated with all studies being exploratory and qualitative in nature.

Crash rates

Crancer and Quiring [47] conducted the earliest studies examining the link between mental illness and limitations in driving capacity. They identified that those with psychotic disorders, personality disorders and psychoneurotic disorders had higher rates of reckless driving, negligent driving and driving with defective equipment. Other studies undertaking epidemiological secondary data analysis showed that crashes were more prevalent among people with mental health conditions and that the injuries sustained are more serious, with someone with a mental health condition being more likely to be hospitalised than those without [49]. With regards to the diagnostic groups in these studies, in the second stage analysis of the study conducted by Kastrup, Dupont, Bille, and Lund [50], the most common diagnostic group was found to be personality disorder. The drivers with psychiatric diagnosis were found to be characterised by women, aged 25–54 years. They were more frequently alcohol intoxicated, and with a higher blood alcohol level. They were found to be more likely to be driving a stolen vehicle, without a valid licence, and were found not to have used safety belts at the time of the crash. From this study it appears that those with personality disorders are having crashes due to the behavioural manifestations of their condition; that is, they undertake risky behaviours that impact on their ability to drive safely. Elkema, Brosseau, Koshnick, and McGee [48] also reported the highest crash rate of those with mental health conditions was those with personality disorders. In this study, it was noted that the behavioural traits demonstrated by those with personality disorders were very different in substance to those with significant mental illness due to depression and bi-polar disorders, associated with an impairment of executive level function.

Impact of specific mental health conditions on the ability to drive safely

Research to date appears to suggest that the behavioural, cognitive and psychomotor impairments that reduce fitness-to-drive may differ between different diagnostic groups. Crancer and Quiring [47] conducted one of the earliest studies on the link between mental health conditions and driving capacity, associating psychotic disorders, personality disorders and psychoneurotic disorders with impaired fitness-to-drive. Due to the age of this study, these findings may need to be reinvestigated as improvements in medication and healthcare for people with these conditions may alter the findings. However, in a recent study Segmillar et al. [40], also found patients with schizophrenia had impaired psychomotor function that could not be attributed to side effects of psychopharmacological treatment, although no chronological decline was found in the early stages of the disease. Similarly, Brunnauer and Laux [51] concluded that even when stabilised with antipsychotic medication, a great proportion of schizophrenic patients are not fit to drive.

For those with major depressive disorder, Bulmash et al. [8] reported higher levels of sleepiness when driving, irrespective of medication use. Similarly, Wingen et al. [9] also concluded that impaired driving performance in this population is probably not due to antidepressant medications. This finding of a high level of sleepiness suggests that behavioural approaches to keep alertness levels higher may need to be considered, such as shortening routes, not eating a heavy meal before driving, and having a caffeine drink half an hour before driving. These interventions could be tested in a simulator experiment to see which elements are most effective for people with major depressive disorders. When comparing the results from Bulmash et al. [8] and Zingg, Puelschen, and Soyka [41], it appears that major depressive disorder is associated with a more widespread impact on the skills needed for driving than those with bi-polar disorder. Zingg, Puelschen, and Soyka [41] found that bi-polar disorder did not impair information processing and driving ability specifically; but rather that poor information processing maybe an underlying weakness of those who commit driving offences. This hypothesis could be researched by introducing information processing testing as part of a standard driving test, and then conducting prospective research to determine the threshold that relates to safe driving.

Another issue raised for drivers with bi-polar disorder relates to self-insight, which resonates with the view of those with bi-polar disorder feeling that the fitness-to-drive guidelines are discriminatory. Reduced self-insight is of real concern for drivers in hypomanic and manic states, who may have ideas of grandeur and reduced self-regulation. Reduced self-insight and self-regulation may be an issue for those with bi-polar disorder requiring further attention in this population specifically, as these capacities do not appear to be impaired by all mental health conditions. The self-report of symptoms affecting capacity to drive identified by Rouleau, Mazer, Menard, and Maryse [45] matched some of those factors measured in a driving simulator, in that people with mental health conditions (predominantly mood disorders) recognised that their condition and medication caused them to have poor concentration, fatigue, dizziness, and sometimes feelings of aggression and nervousness. They reported being more careful when driving or not driving at all when experiencing these symptoms. For those individuals with a mental health condition currently not driving, even though they possess a licence, this suggests a component of self-regulation. The evidence presented by De Las Cuevas and Sanz [37] supported the fact that some drivers with mental health conditions do self-regulate, but only up to a point, since none of the drivers reported their mental health condition to licensing authorities. The issue of non-reporting may be linked with reduced insight about the need to do so or with the associated fear of licence suspension or cancellation.

Health professionals’ role in assessing fitness-to-drive

Alongside licensing authorities, medical professionals, occupational therapists and psychologists are involved in licensing decisions for drivers with mental health conditions. Menard et al. [43] found that only one quarter of psychiatrists felt skilled in making fitness-to-drive decisions. Half of these psychiatrists felt that people with mental health conditions were more likely to be involved in a crash. Studies have examined the rate of recording of assessment of fitness-to-drive by these professionals, as well as the documentation of advice on managing medication and its impact on driving. In one study, only half of those patients needing advice on the impacts of medication on their ability to drive, had this noted in their medical records. Additionally, there was minimal recording of how the mental health condition itself would impact on the patient’s driving capacity [42]. Over half of these psychiatrists said that they had advised on this issue, but it was not evident in the medical notes. Similar results were found by Menard et al. [43], who noted that psychiatrists were only aware of whether their patient was an active driver in a quarter of cases, and for these patients, psychiatrists were more likely to advise on medication impacts than effects of the medical condition. Rouleau, Mazer, Menard, and Maryse [45] also noted that psychiatrists paid attention to medication side effects on fitness-to-drive, alongside mood.

While psychiatrists may focus on the impact of medication on fitness-to-drive, occupational therapists are able to take clients for on-road driving tests and have been noted to emphasise the driver’s physical status, cognitive skills, impulsivity levels and driving history [44, 46] to assist determine fitness-to-drive. Focussing on impulsivity levels may be regarded as important, since impulsivity can be related to risk taking behaviours and difficulty self-regulating; characteristics present in the profile of those drivers most likely to crash [38, 48, 49]. Menard et al. [44] additionally found that occupational therapists paid attention to the client’s perception of their driving ability, factors impacting on their driving capabilities, and identifying goals related to driving. The emphasis was therefore on the person’s meta-cognitive functions related to self-regulation, risk taking behaviour and on-road driving ability, rather than on the effects of medication or the medical condition itself. Similar results were reported by Vrkljan, Myers, Blanchard, Crizzle, and Marshall [46], with occupational therapists in the study also in favour of the use of an on-road assessment to inform decision making in clients with a mental health conditions. The on-road assessment was used and seen by most participants as the most valid means of making fitness-to-drive recommendations, over-riding clinic-based test results (including simulation), in cases where the clinic-based test had indicated negative results. With clinic-based tests and simulation results lacking predictive validity when used alone [8], on-road assessment is important to consider with drivers with mental health conditions where there is a doubt about their capacity. As noted above, although literature on ADHD was not included in this review, Jerome et al.’s., [26] systematic review of the ADHD and driving literature also suggest that risk taking is an important area for further investigation. In particular, driving anger and aggression have been consistently associated with risky driving, and therefore health professionals can work off-road with clients to develop flexible strategies to better manage these emotions.

Crash statistics

A number of studies examining the correlation between mental health conditions and risk of crash have shown an association between significant mental illness and primarily higher level cognitive functions, when drivers were tested in a simulator. For example, Bulmash et al. [8] showed that those with major depressive disorders showed slower steering reaction times and a greater number of car crashes when compared to controls using a driving simulator. Driving simulation experiments appear to show that impaired executive functions impact on driving capacity, yet this is not always borne out in crash data held by licensing authorities [39]. One group that does seem to be over-represented in crash rate data, however, is those with personality disorders. Crancer and Quiring [47] confirmed variation in impairment and crash rates, due to diagnostic group. When compared to controls, statistically higher crash rates were identified in both the personality disorder group (114% higher) and in the psychoneurotic group (49% higher), whereas crash rates in the schizophrenic group were similar to the control group. Of note are the findings of Eelkema, Brosseau, Koshnick, and McGee [48] who showed that with treatment, crash rates decreased for all mental health conditions, apart from those with personality disorders. This is an interesting finding to compare against people with ADHD. While people with personality disorders and ADHD demonstrate several of the same traits such as inattentiveness and impulsiveness, in drivers with ADHD, the negative driving outcome are more focussed on driving violations and citations rather than crashes [26]. Approaches to improving safe driving behaviour in those with personality disorders and ADHD require further investigation.

Licensing authority actions concerning renewal, suspension, or cancellation of a person’s driving licence appear to be closely tied with evidence of crashes. Drivers who do not self-report mental health condition/s may come to the attention of licensing authorities after being involved in one or more crashes, and a relationship appears to exist between involvement in a crash and having a driving licence revoked among people with mental health conditions. However, this relationship may not be warranted. For example, in a case control study by Niveau and Kelley-Puskas [39], people reported to the authorities due to severity of psychiatric disease, were actually more likely to have a clean driving record in relation to crashes and violations than those who were not reported. Hence license revocation seemed to be due to the perceived severity of psychiatric disease itself rather than capacity to drive safely. The judgment of fitness-to-drive in this study was based on clinical or medical records, which is far less accurate that on-road assessments. As noted above, further studies investigating how fitness-to-drive recommendations are made for people with mental health conditions are warranted, and would reveal any inherent biases. Of course, licensing authority staff and health professional may always err on the side of caution, as although revoking a person’s driving licence can limit quality of life and subsequent health of the driver, this has to be balanced against allowing an unsafe driver to continue driving. The key is determining whether the driver with a mental health condition is any more unsafe than other drivers, and there is currently insufficient evidence to guide this decision.

Limitations and directions for future research

This systematic review was limited by the English language restriction imposed, as several studies published in other languages, such as German, could not be accessed. A meta analysis was not possible since studies were generally of low quality and heterogeneous in terms of aims and mental health conditions included. For example, while there is preliminary evidence to suggest that psychomotor skill levels and crash rates are different for populations of drivers with major depressive disorders, schizophrenia, bi-polar disorder and personality disorders, too few studies exist to allow for analyses and recommendations to be made. In contrast, such meta –analyses have been undertaken by pooling study data in the area of drivers with ADHD [26]. Future studies also require larger populations of each diagnostic group so that the impact of key variables on fitness-to-drive outcomes such as years of driving experience, medication use, and severity of the condition, can also be investigated. A systematic review of the 24 papers located that investigate the impact of medication use on drivers with mental health conditions is also required. This new review could also compare findings against comparable studies from the current review that did not specifically investigate the impact of medication on driving. The quality of future studies could also be increased by including age and sex-matched controls where possible, and the inclusion of longitudinal follow-up of people with mental health conditions who both do and don’t drive. It is generally the driver’s duty to report to the licensing authority any permanent or long-term condition which may impact on their fitness-to-drive. With regards to mental health conditions where a person’s insight may be affected, drivers may not be able to detect a problem and may continue to drive when they are not safe to do so. When individuals continue to drive when they are not fit to do so, this creates legal and ethical issues for treating health professionals, as well as the affected individual’s family.

This review has demonstrated that a number of health professionals feel ill-equipped to make fitness-to-drive recommendations for people with mental health conditions. General medical practitioners are expected to conduct assessments to identify individuals who may be unfit to drive, as well as to provide information to the driver licensing authority on an individual’s diagnosis, treatment and extent of impairment. Numerous studies have indicated that few general medical practitioners have any formal training, specific to fitness-to-drive [52–54], although a recent concerted national education programme on medical fitness to drive has proved effective for Irish general practitioners [55]. Furthermore, while specialist driver-assessor occupational therapists do play a role in assessing fitness-to-drive of a wide range of people with heath concerns and age-related health declines [55], the literature provides limited information about their attitudes, practices and knowledge regarding fitness-to-drive among individuals with mental health conditions [44]. Finally, it may be the case that recommendations of fixed time limits for driving cessation imposed on people with mental health conditions may be unrealistic, lack an evidence base and are possibly ignored by health professionals. Whether to suspend, cancel, renew, or issue a person’s driving licence has considerable impact on not only a person’s health, but also on the subsequent health and well-being of all road users. Currently, insufficient evidence exists to support fair and equitable decision making for fitness-to-drive among people with mental health conditions, and further research is required to support health professionals in this area.