Neuropsychological Services Are Essential for Depressed Patients among Transport Industry Workers

Introduction

In a recent systematic meta-analysis of suicide among transport industry workers, it was found that these workers have a significantly higher risk for suicide than people in the general employed population (Matthieu et al., 2022). The potential risk of depression and suicide, especially after COVID-19 pandemic, has also been recently recognized in the related aviation industry (Vuorio & Bor, 2020). It has been established that neurocognitive performance is directly affected by mood disorders and among transport workers (e.g. aviation, shipping, oil and gas, train drivers, truck and logistics operators as well as bus drivers, among others), and this in turn can impede response and reactions times, cognitive capacity, concentration, attention, auditory and visual processing, among other higher level cognitive functions (Keilp et al., 2013; Jollant et al., 2011). Diagnosis and treatment of mood disorders, through selective serotonin uptake inhibitors combined with transcranial magnetic stimulation, have shown be beneficial (Schillin et al., 2021) and may improve cognitive impairments and therefore safety in transport systems. Unfortunately, the number of psychiatrists, psychologists, neurologists, and neuropsychologists across European countries is low (Kasten et al., 2021). There is a need to improve availability of such specialist services, as well as harmonize qualifications of these professionals between the European countries. For specific transport profession, such as airline pilots, there is a need to have neuropsychologists specialized in aviation.

Suicidal ideation and suicidal attempts

There is a need to understand more about suicidal behavior, using neuropsychological and neuroimaging methodology, because predicting and preventing suicide is challenging. A suicide attempt is often triggered by the culmination of complex pathological processes, impulsively or over a longer period of time. In and of itself, expressing suicidal thoughts is quite common in depressed patients, without ideation necessarily leading to suicide. For example, in the questionnaire-based study carried out in 2015 among nearly 2000 airline pilots, 13.5% met the criteria for depression based on responses to the Patient Health Questionnaire 9, and 4.1% of these pilots had had suicidal thoughts within the previous two weeks (Wu et al., 2016). Regarding commercial aircraft-assisted suicide accident investigations a detailed psychological autopsy of pilots is utmost important (Vuorio et al., 2023). It is generally estimated that about half of patients with a mood disorder have suicidal thoughts (Kessler et al., 1999). However, the presence of suicidal thoughts is a relatively poor predictor of suicide attempt (Nock et al., 2017).

The recent controlled study of 106 patients who had psychiatric diagnoses without suicidal ideation/behavior or with suicidal ideation or with suicide attempts (Comparelli et al., 2022). 
These 106 patients were divided into three groups stratified by suicide risk level: suicide attempt, suicidal ideation, patient controls, and healthy controls. Then it was analyzed whether there were differences between the neurocognitive profiles between the groups. When neurocognitive assessments were performed it was found that social cognition impairment presented among those patients who had either suicidal ideation or suicidal attempts. If patients have social cognition impairment, this may reflect a diminution or absence of the recognition of one’s own or other people’s emotions. Furthermore, emotional regulation may be impaired or compromised. This study demonstrates that neurocognitive profiling provided with the help of neuropsychological testing may help to screen for and assess risk in suicidal behavior among those with mood disorders. It is possible that specific cognitive therapeutic interventions aimed at improving social cognitive functions, like decreasing impulsivity and increasing decision-making, may be used clinically in suicide prevention.

Neuropsychological tests can be compared with modern functional neuroimaging findings. This approach was used in a recent study (Kashimura et al., 2022). Patients with the history of suicide attempts showed significantly higher impulsivity and hopelessness when compared healthy controls. Interestingly, the functional neuroimaging during emotional recognition test showed that these features were associated with increased responses in specific parts of the frontal cortex. It is known that the frontal cortex is responsible for controlling responses to emotions, among many others. 

Suicidal behavior risk is modified by cognitive traits that may differ from the psychopathology of associated psychiatric illnesses (Mann & Rizk, 2020). It needs to be emphasized that the challenge in understanding brain neuropsychology is not only to understand the association between different parts of brain and suicidality, but to also to understand dysfunction between brain networks. This was shown in meta-analyses demonstrating that there is hypoconnectivity in depressed patients between frontal cortex, which is responsible for controlling emotions, among other functions, and other parts of brain responsible of cognitive regulation and control (Kaiser et al., 2015). 

Neurocognitive profile in depression

Further studies have investigated cognitive functioning during depression. Some of the neuropsychological defects are related to depressive symptoms, but some of these defects persist after the depressive symptoms disappear. It has been shown that in the acute phase, processing speed, learning, and memory are impaired (Kriesche et al., 2022). In addition to traditional clinical symptoms of depression, there are also less recognized neurocognitive symptoms in patients (Hammar et al., 2022). If there is a paucity of neuropsychological assessment clinicians, neurocognitive defects in depressive patients may go unrecognized. These specific neurocognitive defects have relevance especially when assessing and treating those who work in the public transport sectors and related occupations. Antidepressant treatment may, itself, have a positive effect on cognitive functions. A very recent study showed that medication with Vortioxetine after depression followed 1 and 3 months by COVID-19, significantly improved cognitive functioning measured by two different neuropsychological tests (Di Nicola et al., 2023). Although these results are preliminary and there still needs to be larger-scale studies of this patient group, these results demonstrate that at least certain new antidepressants may have a beneficial, targeted effect on cognitive functioning in individuals recovering from depression. This could have a significant effect on those being treated for depression in cognitively demanding transport occupations, such as airline pilots and train drivers.
    
Neuropsychological findings in depressed suicidal patients

Cognitive processing among depressed, suicidal patients is not yet well understood although some of those who may go on to attempt to act on suicidal thoughts have been found to be cognitively rigid. Cognitive processing has been studied among depressed people who have made suicide attempts in the past and some were found to have neuropsychological deficits (Keilp et al., 2001). In this study, depressed patients with a history of suicide attempts had significantly worse general intellectual functioning, attention, and memory. These differences were not attributable to education or occupation. These findings can be associated with prefrontal cortical dysfunction. Neuropsychological dysfunction or pathology may contribute to suicide risk by impairing decision-making.

In conclusion

The neurocognitive effects of depression are the subject of contemporary research. Findings are largely based especially on studies that have combined functional neurological imaging methods with neuropsychological tests. It has been already shown that in the acute phase, processing speed, learning and memory may be impaired in depression. Furthermore, it has been shown that depressed patients with a history of suicide attempts have significantly worse general intellectual functioning, attention, and memory than in their pre-morbid state. Certain antidepressant treatments may have positive specific impact on cognitive functions. Additionally, specific cognitive therapeutic interventions, aimed at improving social cognitive functions like decreasing impulsivity and increasing decision-making may be useful in suicide prevention. There is a need to improve the availability of neuropsychological services as well as harmonize qualifications of clinical neuropsychology between the European countries. For safety-critical workers in the transport industry, there is a need to have neuropsychologists available to assist in the assessment and treatment of depressed workers and in assisting in determining when they are fit to operate again.

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