Brain Function After Cardiac Arrest (Measured With FMRI and Cognitive Tests)

The aim of this longitudinal study is to determine whether brain function is affected after a cardiac arrest.

The primary question is whether cognitive function is affected after cardiac arrest and whether it changes over time (during the first year after the event), compared with a healthy control group. Brain function during cognitive tasks and emotion processing will also be studied using functional MRI (fMRI). Another aim is to study whether clinical outcomes such as PTSD, anxiety and depression can be correlated with cognitive function and whether health- related quality of life is affected after a cardiac arrest.

The results from the cardiac arrest patient group will be compared with a healthy control group.

The study is a prospective cohort study and aims to enroll 30 cardiac arrest patients and 30 matched (regarding age, gender and level of education), healthy controls.

Patients who are enrolled in the study will on three different occasions (in the acute phase, after six and after twelve months) answer questions regarding their health state and perform a computerized cognitive test and a behavioral test.

Patient/ control health status will be assessed through the following tests:

* Cognitive function will be assessed using the Montreal Cognitive Assessment (MoCa) screening tool which measures attention/concentration, executive functions, memory, verbal skills, visual construction skills, abstract thinking, computation and orientation.
* Presence of delirium will be assessed using the Confusion Assessment Method for the Intensive Care Unit (CAM- ICU) and will be complemented with information from the patients' medical records.
* The Richmond Agitation - Sedation Scale (RASS) will be used to assess sedation.
* Health- related quality of life will be measured using the three level version of EQ-5D (EQ-5D-3L; Euro-Qol 5-Dimensions).
* A Mini International Neuropsychiatric Interview (MINI) will be performed to detect psychiatric syndromes (such as PTSD, anxiety and depression). Symptoms of anxiety and depression will also be measured using The Montgomery-Åsberg Depression Rating Scale- Self report (MADRS-S) and Impact of Event Scale-Revised -22. Alcohol use will be assessed using AUDIT (Alcohol Use Disorders Identification Test).

Information will also be collected from the patients' medical records.

Cognitive/ neuropsychological testing will be performed using the Cambridge Neuropsychological Test Automated Battery (CANTAB), which measures amongst others memory, planning, executive functions and attention. For this study, the following CANTAB modules will be used:

* Delayed matching to sample (DMS)
* Paired associate learning test (PAL)
* Stockings of Cambridge (SOC)/ One Touch Stockings of Cambridge (OTS)
* Motor Screening Task (MOT), which provides a general assessment of whether sensorimotor deficits or lack of comprehension will limit the collection of valid data from the participant.

The tests are performed on a tablet. All task stimuli are non- verbal.

An approach- avoidance test that measures avoidance behavior will also be performed. Patients will be presented with auditory and visual (pictures) stimuli and will choose whether the stimuli presented to them will be of a neutral or aversive character. Patients will be informed that choosing the aversive stimuli will reward them with a small amount of money.

Functional magnetic resonance imaging (fMRI) will be performed six and twelve months after the cardiac arrest. The MRI scan will also include morphological images. The fMRI sequence will include tests regarding emotional activation, emotional memory and cognitive interference. A DMS task with emotionally loaded stimuli will be performed. Blood oxygenation level dependent (BOLD)- imaging will be used to produce the fMRI images, where differences in blood flow in different parts of the brain will be registered through echo planar imaging (EPI). The images will be analyzed with the Statistical Parametric Mapping (SPM)-12 program using MATLAB computing language.

The healthy control group will on two occasions (with the second occasion taking place six months after the first) answer questions regarding their health state, perform cognitive testing and fMRI. The same will be assessed for the control as for the patient group, with the exception of CAM-ICU, RASS and information from medical records, which will not be included in the control group.

Eligibility Criteria:
Inclusion Criteria:

* Patients who have suffered a cardiac arrest of cardiac cause who were admitted to hospital after the event.
* Age 18-70
* Consents to participating in the study

Exclusion Criteria:

* Terminal disease with expected survival \<1 year, moribund patient with \>1 treatment limitations.
* A history of brain injury or brain disease that affects cognitive function, such as dementia
* Severe psychiatric disorder, for example psychotic disorders or severe alcohol use disorder
* Insufficient knowledge of the spoken language to understand instructions and answer questionnaires (oral or written)
* Deceased within 1 month.