Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Neuroscience

Supervisor

Owen, Adrian M.

2nd Supervisor

Honarmand, Kimia

Co-Supervisor

Abstract

Approximately half of patients who have cardiac surgery will experience deficits in attention, memory, and thinking speed after their operation. Given that heart surgery is one of the most common medical procedures in Canada, it is necessary to better understand the natural history of cognitive impairment after such surgery. Yet, there is no globally accepted method for measuring cognitive function in patients who undergo heart surgery. To address this, we assessed whether it was feasible to use a web-based approach to measure cognition in heart surgery patients before and after their operation. Findings showed that remote administration of cognitive testing was feasible. Relative to healthy age and sex-matched controls, cardiac patients showed impairment on the Creyos battery before and after surgery, specifically on tasks that relied on verbal processing skills. This study will help identify vulnerable patients and inform future interventional trials to promote cognitive recovery and improve patient quality of life.

Summary for Lay Audience

Patients who have heart surgery may experience decreased thinking ability, memory and attention after their surgery1-5 – collectively known as cognitive impairment. These impairments are seen in between 50 – 80% of patients and tend to persist long after heart surgery.6-10 Given that heart surgery is one of the most common medical procedures in Canada,11it is important to investigate how and why this impairment may occur. To date, there is no agreed upon method to test thinking ability in heart surgery patients. Previous research has used different tools to test patients, which has led to inconsistent conclusions.3,12 It is necessary to establish a tool that can be used widely to reduce inconsistency in diagnosing cognitive impairment after heart surgery. Therefore, the present study aims to assess whether using the Creyos Research cognitive platform is feasible among heart surgery patients. The Creyos platform consists of virtual assessments designed as games that patients may complete from home.13-15 The ultimate goal of this research project is to evaluate thinking ability and recovery among heart surgery patients to establish a framework for identifying what are the key factors responsible for the impairments observed.

To this end, I recruited patients ≥18 years old who were scheduled to undergo heart surgery at London Health Sciences Centre and Hamilton Health Sciences and asked them to complete testing before surgery and at 1, 3, 6 and 12 months after their operation. Of 20 participants who completed the cognitive testing, 16 showed severe impairment on at least one Creyos test before surgery. The most severe impairment was found on tests that were associated with verbal processing ability, which suggests a specific pattern of impairment. We also found that using virtual methods to assess thinking ability in a group of heart surgery patients was feasible. The results of this study can inform the design of larger trials to investigate potential treatment of cognitive impairment after cardiac surgery.

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