14 - Psychiatric Disorders
14.1 About psychiatric disorders
The Diagnostic and Statistical Manual of Mental Disorders (DSM-5)*, published by the American Psychiatric Association, contains a standard classification system of psychiatric disorders for health care professionals in the United States and Canada. It classified psychiatric disorders into diagnostic categories. A previous edition (APA, 2000**) utilized five axes, but that multi-axial system was removed from the most recent edition.
(* American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Washington, DC)
(**American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC)
Delirium, dementia, and other cognitive disorders
The effects of delirium, dementia and other cognitive disorders on driving are covered in Chapter 6, Cognitive Impairment including Dementia. It is worth noting that the DSM-5 has relabeled dementia as “Major Neurocognitive Disorder”, and more subtypes (e.g. Lewy Body dementia) are described, organized by the cause, time course, domains affected, and associated symptoms. The DSM-5 retains the term dementia as an alternative to Major Neurocognitive Disorder.
Substance-use disorders refer to the taking of a drug of abuse (including alcohol), despite significant substance-related problems, including medical (e.g. liver disease), physiological (e.g. tolerance and withdrawal), psychological (e.g. cravings), and social (e.g. negative impact on work, school, or home life). Substance-induced disorders refer to a category of apparent behavioral disturbance presumably related to ingestion of a substance (e.g. intoxication or withdrawal), or mental disorder (e.g. substance/medication-induced depressive disorder). Substances include alcohol, amphetamines, cannabis, cocaine, hallucinogens, sedatives, hypnotics and anxiolytics. Alcohol and illicit drug use disorders are not considered in this document. The effects of drugs commonly prescribed for medical conditions are addressed in Chapter 15, Drugs, Alcohol and Driving.
Depressive Disorders - Major Depressive Disorder, or Persistent Depressive Disorder (Dysthymia)
Major Depressive Disorder is characterized by one or more episodes of depressed mood or loss of interest in usual activities, as well as four additional symptoms of depression, with the episodes lasting for two or more weeks. Additional symptoms of depression include:
- change in appetite
- sleep disturbances
- decreased energy or fatigue
- sense of worthlessness or guilt, and
- poor concentration or difficulty making decisions
Persistent depressive disorder (dysthymia) refers to a condition in which mood is persistently depressed for at least 2 years, along with at least two other symptoms such as low self-esteem, hopelessness, appetite or sleep changes, fatigue, difficulty concentrating or making decisions.
Other Depressive disorders include:
- Disruptive Mood Dysregulation Disorder
- a diagnosis characterized by severe and recurrent verbal or physical temper outbursts.
- Generally, this is a diagnosis made in childhood, and “should not be made for the first time after age 18 years”, but is included here since it may persist into adulthood.
- Premenstrual Dysphoric Disorder
- Characterized by symptoms such as mood instability, irritability, depressed mood, or anxiety occurring in conjunction with the majority of menstrual cycles.
- Depressive disorders induced by substances/medications or medical conditions
Bipolar I Disorder is characterized by one or more manic episodes, with or without a history of major depressive episodes. Bipolar II Disorder is similar, but instead of manic episodes, major depressive episodes alternate with hypomanic episodes. Hypomanic episodes are different from manic episodes, as they are of shorter duration, and are not associated with significant impairment in functioning, psychosis or a need for hospitalization.
Cyclothymia is similar to Bipolar II Disorder except that symptoms of depression have not met full criteria for a major depressive episode. Other disorders in the bipolar spectrum are those felt to be due to drugs, substances or other medical conditions.
There are a number of anxiety disorders classified in the DSM-5, including:
- Generalized Anxiety Disorder
- Specific phobias
- Social Phobia
- Panic Disorder.
Symptoms include intense and prolonged feelings of fear or distress that occur out of proportion to the actual threat or danger. The feelings of distress also must be sufficient to interfere with normal daily functioning.
Obsessive compulsive disorder, acute stress disorder, and post-traumatic stress disorder are considered in DSM-5 in separate categories from Anxiety Disorders, although it is acknowledged that anxiety is a common feature of these as well.
Obsessive Compulsive Disorder is characterized by recurrent obsessions (“recurrent and persistent thoughts, urges, or images that are experienced as intrusive and unwanted”) and/or compulsions (“repetitive behaviors or mental acts that an individual feels driven to perform…”).
Acute Stress Disorder and Posttraumatic Stress Disorder (PTSD) refer to the development of symptoms after exposure to a traumatic event. Symptoms include intrusive memories, avoidance of reminders of the trauma, alterations in mood, memory or arousal. The duration of Acute Stress Disorder is up to one month after the trauma, and the duration of PTSD is more than one month after the trauma.
Attention-Deficit/Hyperactivity Disorder (ADHD) is characterized by inappropriate degrees of inattention, impulsivity and overactivity that begin in childhood. ADHD is one of the most common neurobehavioral disorders of childhood and can persist through adolescence and into adulthood.
Although many individuals with ADHD show symptoms of both inattention and hyperactivity-impulsivity, there may be a predominance of either inattention or hyperactivity-impulsivity. This variability of presentation is reflected in the three major classifications of the disorder:
- Combined Type (exhibiting both inattention and hyperactivity-impulsivity)
- Predominately Inattentive Type, and
- Predominately Hyperactivity-Impulsivity Type.
The symptoms of hyperactivity and impulsivity tend to diminish over time so that many adults will present with primary symptoms of inattention only.
The effects of Schizophrenia on the individual can be profound. Common symptoms include delusions and hallucinations, thought disorders, lack of motivation and social withdrawal. The symptoms of Schizophrenia are generally divided into three broad categories:
- Positive or “psychotic” symptoms are characterized by delusions (fixed false beliefs), or hallucinations (“perception-like experiences that occur without an external stimulus”).
- Disorganised, illogical or bizarre thoughts, speech or behaviours.
- Negative symptoms are typically characterized by diminished emotional expression or a decrease in motivation and initiation of activities
The onset of Schizophrenia can occur at any age, but most typically appears in early adulthood. Many individuals with schizophrenia have recurring acute positive psychotic symptoms (delusions or hallucinations), or disorganization throughout their life, which are typically separated by intervening periods in which they usually experience residual or negative symptoms.
There are a number of personality disorders identified in the DSM-5, including:
- Borderline Personality Disorder
- Schizotypal Personality Disorder
- Anti-social Personality Disorder, and
- Narcissistic Personality Disorder.
Onset typically occurs during adolescence or in early adulthood. The disorder affects thought, emotion, interpersonal relationships and impulse control. The disorders are characterized by “an enduring pattern of inner experience and behavior that deviates markedly from the expectations of the individual’s culture, is pervasive and inflexible, (and)…is stable over time…”
Intellectual Disability (Intellectual Developmental Disorder)
The DSM-5 defines intellectual disability as deficits in intelligence and adaptive functioning, with onset during childhood development. Individuals with this disorder must also meet the cognitive impairment standard.
Suicidal ideation is defined as having thoughts of suicide or taking action to end one’s own life, irrespective of whether the thoughts include a plan to commit suicide or an actual attempt. Studies indicate that the majority of all suicides are associated with psychiatric disorders.
Mood disorders - Major Depressive Disorder, Bipolar Disorder, Dysthymic Disorder
In Canada, approximately 12.2% of adults will experience major depression at some time in their lives*, with approximately 0.9% experiencing Bipolar Disorder*. Depression is more common among women, but the sex ratio for Bipolar Disorder is approximately equal.
Anxiety disorders are estimated to affect 3.8 – 5.0 % of the Canadian population annually*.
Prevalence rates of ADHD vary, depending on the diagnostic criteria used, the setting (e.g. general population vs. clinic sample) and the reporter (e.g. parent, teacher, self).
The point prevalence of adult ADHD is estimated at 4.4%, and it is estimated that 36.3% of those with ADHD in childhood continue to meet diagnostic criteria in adulthood**.
Schizophrenia is estimated to affect 0.4% of people in the community over their lifetime, with onset typically in early adulthood (late teens to mid-30s). Males and females are affected equally*.
Epidemiological studies show a range of prevalence of personality disorder from 9.0% to 15.7% in international studies of community-based populations.
In 2012, 3296 people died of suicide in Canada, corresponding to a rate of 10.4 deaths per 100,000 people*.
(*Patten, S.B., Wang, J.L., Williams, J.V.A., Currie, S.R., Beck, C.A., Maxwell, C.J., El-Guebaly, N., 2005. Descriptive epidemiology of major depression in Canada. Can. J.Psychiatry 51, 84–90)
(*McDonald, K.C., Bullock, A.G.M., Duffy, A., et al. Prevalence of bipolar I and II disorder in Canada. Canadian Journal of Psychiatry 2015; 60(3): 151-6)
(*Romans, S., Cohen, M., Forte, T. Rates of depression and anxiety in urban and rural Canada. Social Psychiatry Psychiatric Epidemiology 2011; 46: 567-575)
(*Kessler, R.C., Adler, L, Barkley, R. et al The prevalence and correlates of adult ADHD in the United States: Results from the National Comorbidity Survey Replication. American Journal of Psychiatry 163(4): 716-23)
(*Kessler, R.C., Adler, L.A., Barkley, R. Patterns and predictors of ADHD persistence into adulthood: Results from the National Comorbidity Survey Replication. Biological Psychiatry 2005, 57(11): 1442-1451)
(*McGrath, J., Saha, S., Chant, D., Welham, J. Schizophrenia: A concise overview of incidence, prevealnce and mortality. Epidemiologic Reviews 2008, 30(1): 67-76)
14.3 Psychiatric disorders and adverse driving outcomes
Despite the prevalence of psychiatric disorders in the general population, there have been few investigations into the relationship between these disorders and adverse driving outcomes. Surprisingly, the majority of research was done, on average, more than 30 years ago.
There are a number of methodological issues that impact the ability to draw conclusions from the existing research, in particular, the impact of improved treatment of psychiatric disorders and changes in the complexity of the driving environment on the results of older studies. Nonetheless, the consistency of findings supports a general conclusion that drivers with psychiatric conditions are at increased risk of adverse driving outcomes.
Mood disorders - Major Depressive Disorder, Bipolar Disorder, Dysthymic Disorder
A few studies have identified depression as one of a number of factors that may influence driving performance. However, the results of these studies are equivocal, and methodological limitations significantly limit any conclusions that may be drawn.
Pharmacological treatment of mood disorders is an important consideration. When treatment is effective, the alertness, cognitive ability and judgment of a person with a mood disorder may be improved. At the same time, the significant side effects of anti- depressant medications may include impairments in psychomotor functioning, sedation and impairments in cognitive functioning. The impact of the side effects of drug treatment on driving is considered in Chapter 15, Drugs, Alcohol and Driving.
There are no studies that have investigated the relationship between anxiety disorders and driving, although symptoms of anxiety may increase the risk of self reported collisions*.
Pharmacological treatment with sedatives or hypnotics may include side effects that impair functional ability to drive. See Chapter 15, Drugs, Alcohol and Driving, for more information.
(*Wickens, C.M., Mann, R., Stoduto, G., et al The impact of probable anxiety and mood disorder on self-reported collisions: A population study. Journal of Affective Disorders 2013; 145: 253-5)
There is a small body of research that suggests that drivers with ADHD are at a higher risk for crashes, have higher rates of traffic citations and licence revocations or suspensions, and are more likely to drive without a licence.
There is some indication that pharmacological treatment of ADHD with stimulants may have a positive effect on driving performance. However, research in this area has primarily relied on driving simulators to measure outcomes. A few studies have investigated the relationship between pharmacological treatment of ADHD and on-road performance. However, methodological limitations, including small sample size (< 20 in all cases), limit the findings. The effects of pharmacological treatment of ADHD are discussed further in Chapter 15, Drugs, Alcohol and Driving.
The results of the few studies on the relationship between Schizophrenia and adverse driving outcomes are equivocal, although may be related to a reduced rate of licensure and driving exposure, as simulator studies tend to consistently show impairment.
There are no contemporary studies of the risks of collisions associated with personality disorders.
However, two studies, both more than 30 years old, considered the relationship between personality disorders and adverse driving outcomes. Both studies found an increased crash risk for drivers with personality disorders.
Studies on the incidence of traffic suicides indicate that suicide attempts play a significant role in motor vehicle crashes. Moreover, it is likely that the reported incidence rates of traffic suicides are an underestimation, due to the methodological difficulties in classifying a traffic death as suicide.
Research indicates the following risk factors for traffic suicides:
- males are significantly more at risk (90% to 95%) than females
- whites are more at risk than other racial groups
- those who are “depressed” or “mentally disturbed” are more at risk than those who are not, and
- those with a history of attempted suicide or a family history of suicide are more at risk than those without such history.
14.4 Effect on functional ability to drive
|Condition||Type of driving impairment and assessment approach||Primary functional ability affected||Assessment tools|
|Persistent impairment: Functional assessment||
|Episodic impairment: Medical assessment - likelihood of impairment||
|Personality disorders||Persistent impairment: Functional assessment||Affective||Medical assessments|
|Episodic impairment: Medical assessment - likelihood of impairment||Affective||Medical assessments|
Psychiatric disorders can result in either a persistent or episodic impairment of the functions necessary for driving.
The role of insight
A driver’s level of insight is a critical consideration when assessing the risk of an episodic impairment of functional ability due to a psychiatric disorder.
Drivers with good insight are more likely to be diligent about their treatment regime and to seek medical attention and avoid driving when experiencing acute episodes and have the judgment and willingness to adapt their driving to these limitations.
Poor insight may be evidenced by non-compliance with treatment, trivializing the driver`s role in a crash or repeated involuntary admissions to the hospital, often the result of discontinuing prescribed medication.
Affect refers to the observed expression of emotion. The ability to manage one’s affect is an important functional component of safe driving performance. Affect includes:
- emotional intelligence
- impulse control/emotional control
- frustration threshold
- agitation, and
- impulsivity and/or mood control/management
Psychomotor functions affect the coordination of cognitive processes and motor activity.
Abnormalities can include agitation, restlessness, pacing, aimless activity or slowing down of movements or thought. In his document, psychomotor function will be considered as one of the functional abilities needed for driving for drivers with psychiatric disorders.
Mood disorders - Major Depressive Disorder, Bipolar Disorder, Dysthymia
Cognitive abilities that may be affected by mood disorders include:
- attention and concentration
- information processing
- reaction time, and
- psychomotor functioning.
The research on the effects of anxiety disorders on functional ability is limited. Findings from studies examining the effects of anxiety disorders on cognitive functioning are equivocal. Neurobiological studies suggest that medial and temporal lobe structures are affected in anxiety disorders. These are structures that are responsible for memory and higher order executive functioning. From a clinical perspective, the potential for diminished attention or perseverating on errors (including “freezing”) in the face of unexpected risks on the road may be of concern for driving.
The pattern of deficits in adults with ADHD is similar to that in children and adolescents. One of the primary cognitive functions that may be affected is the ability to sustain attention, particularly when performing demanding cognitive tasks. In addition to attentional impairments, individuals with ADHD often experience other cognitive deficits such as difficulties with:
- planning and forethought
- problem solving
- working memory, and
- response inhibition.
Symptoms of ADHD referenced in the DSM-5 that may be relevant to driving include:
- often fails to give close attention to details or makes careless mistakes in school work, work or other activities
- often has difficulty sustaining attention in tasks or play activities
- often is easily distracted by extraneous stimuli
- often is “on the go” or acts as if “driven by a motor”
- often has difficulty awaiting his or her turn
Apart from the core symptoms of psychosis (delusions, hallucinations, disorganized thoughts and (behavior), apathy and neuropsychological deficits associated with schizophrenia may impact driving. The degree of functional impairment associated with schizophrenia varies between the acute and residual phases of the disorder.
Neuropsychological functions that may be impaired include:
- executive function
- spatial abilities
- memory, and
- motor and tactile dexterity.
The characteristics of personality disorders most likely to affect driving include:
- affectivity (e.g. aggression, frustration, anger)
- interpersonal functioning (e.g. failure to conform to social norms, reckless disregard for the safety of others), and
- poor impulse control.
Suicidal ideation is an important consideration regarding drivers with psychiatric disorders because of the risk of traffic suicide.
In addition to the direct effects of psychiatric disorders on functional ability to drive, the impact of pharmacological treatment is an important consideration when assessing drivers. The effects of drug treatment are considered in Chapter 15, Drugs, Alcohol and Driving.
Drivers with psychiatric disorders are not able to compensate for their impairments.
14.6 Guidelines for assessment
National StandardNote: Requires ballot as 6 months is dropped
All drivers eligible for a licence if
|Conditions for maintaining licence||
RoadSafetyBC will impose the following conditions on an individual who is found fit to drive
|Information from health care providers||
|Rationale||Given the nature of psychiatric disorders, assessment must rely primarily on the clinical judgment of health care professionals involved in treatment. Where the disorder results in a persistent impairment, the impact of that impairment should be functionally assessed|