Does Chronic Obstructive Lung Disease Influence the Cognitive Function

Does Chronic Obstructive Lung Disease Influence the Cognitive Function: Assessment Using a Driving Simulator and Other Cognitive Tests

Studies have documented impaired cognitive function in patients with COPD. The possible reasons for this and correlation to the severity of the disease are not well described. This explorative study examines the cognitive skills of COPD patients, quantified by their ability to drive a vehicle and other cognitive test. Furthermore, we want to study the cognitive skills in COPD patients before and after they are diagnosed with and treated for obstructive sleep apnoea (OSA). The overall hypothesis is that chronic lung patients´ cognitive skills correlate with the severity of their disease. We expect that their ability to drive a vehicle drops in relation to the severity of the disease and to comorbidities.

200 COPD patients recruited from the outpatient clinic at the Department of Respiratory Diseases at Vejle Hospital. Approximately 2600 COPD patients are treated in Vejle.

For this study a driving simulator is being used. The subjects are placed in front of a computer monitor which simulates a horizon on the middle of the screen, and a road that appears in the bottom half of the screen. The subjects are encouraged to keep the virtual vehicle on the road, using a steering wheel in front of them. Simultaneous, they are required to keep focus on both sides of the screen where a line of numbers is frequently changing. Every time the number 2 occurs, the subjects must press a button on the steering wheel.

The subjects´ overall ability to control the driving simulator is being expressed by the standard deviation (sd) of distance of the car´s centre to the centre of the road and the number of off-road events. Relevant cognitive measurements, such as reaction speed and ability to split attention, are quantified by the reaction speed to the occurrence of the number 2. The reason for this is that the software of the simulator measures the mean reaction time from the number have occurred until the correct button is pressed, and the number of nil-responses, where the number 2 is not detected.

Every participating subject will receive a 5 minutes testing period of the simulator followed by 30 minutes of applicable driving time.The other tests will be performed/collected just after the driving test.

Besides the driving simulator and tests (see sections below) following are obtained: 1) Lung function (FEV1, FVC and FEV1/FVC), 2) Arterial blood sample including PaO2, PaCO2 and carbonmonooxidhemoglobin (HbCO) (1.5 ml), 3) Smoking status and number of pack years, 4) Status of oxygen therapy, 5) Number of COPD exacerbations in the last year, 6) Comorbidities such as diabetes, metabolic diseases, cardiovascular diseases, kidney insufficiency, 7) Medicine, 8) Height and weight, 9) Level of education, 10) Degree of dyspnoea Medical research Council breathlessness scale (MRC-scale) and 11) Global initiative for chronic Obstructive Lung Disease (GOLD) classification of airflow limitation.

The blood samples will be analysed immediately after they are taken, and as a consequence no biobank will be established. The information will be gathered from the journals and from patient interview in connection with the trial. The information will be used in the assessment of possible reasons to COPD patients´ expected reduced cognitive skills.

The NOX T3TM (see section below) will be delivered in connection with the trial. If the patients are diagnosed with OSA they will shortly after receive standard treatment in the public Sleep Clinic at Vejle Hospital, if the patients accept. After 2-3 month of treatment, the patients will repeat all the tests and blood samples, except the cardiorespiratory monitoring.

To exclude that an improvement of skills is not due to the patients having learned how to improve the test, we will establish a control group. The control group must consist of COPD patients without OSA who must perform a retest like the patients with OSA.

Inclusion Criteria:

1. Doctor-diagnosed chronic obstructive lung disease (forced expiratory volume in the first second (FEV1) / forced expiratory vital capacity (FVC) <0.70).
2. Severity of COPD - GOLD 3+4 (GOLD 2019 classification).
3. No exacerbations in the last 6 weeks (aggravation of the respiratory symptoms compared with habitual state, which require treatment).
4. Age ≥ 40 years and ≤ 75 years
5. The patient must have driven a vehicle within the last 3 months.

Exclusion Criteria:

1. Lacking the ability to operate the driving simulator (physical deformities or lack of comprehensive skills to understand instruction of operating the simulator).
2. No valid driver´s license.
3. Do not read and understand Danish.
4. Known obstructive sleep apnoea (OSA).
5. Alcohol consumption (>21 units per week for men, >14 units per week for women).
6. Consumption of alcohol and/or narcotics within the last 24 hours.
7. Uncorrected sight- or hearing reduction.
8. Unstable ischemic heart disease, uncontrolled hypertension or diabetes, left sided heart failure, serious neurologic conditions, cancer, phlebitis, severe psychiatric diseases, uncontrolled thyroid disease or former apoplexy.