Cognitive impairments and subjective cognitive complaints after survival of cardiac arrest: A prospective longitudinal cohort study

Abstract

Background

Cardiac arrest can lead to hypoxic brain injury, which can affect cognitive functioning.

Objective

To investigate the course of objective and subjective cognitive functioning and their association during the first year after cardiac arrest.

Methods

A multi-centre prospective longitudinal cohort study with one year follow-up (measurements at two weeks, three months and one year). Cognitive functioning was measured with a neuropsychological test battery and subjective cognitive functioning with the Cognitive Failures Questionnaire.

Results

141 cardiac arrest survivors participated. Two weeks post cardiac arrest 16% to 29% of survivors were cognitively impaired varying on the different tests, at three months between 9% and 23% and at one year 10%–22% remained impaired with executive functioning being affected most. Significant reduction of cognitive impairments was seen for all tests, with most recovery during the first three months after cardiac arrest. Subjective cognitive complaints were present at two weeks after cardiac arrest in 11%, 12% at three months and 14% at one year. There were no significant associations between cognitive impairments and cognitive complaints at any time point.

Conclusions

Cognitive impairments are common in cardiac arrest survivors with executive functioning being mostly affected. Most recovery is seen in the first three months after cardiac arrest. After one year, a substantial number of patients remain impaired, especially in executive functioning. Because of absence of associations between impairments and complaints, cognitive testing using a sensitive test battery is important and should be part of routine follow-up after a cardiac arrest.

Introduction

Cardiac arrest (CA) can lead to ischemic-hypoxic brain injury with subsequent cognitive deficits varying from mild to severe and affecting different domains of cognitive functioning [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]. Most reported deficits are loss of memory, psychomotor deficits and problems in executive functioning [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]. At three months post arrest, Ørbo concluded that 44% in a cohort of 45 survivors were cognitively impaired to some degree [8]. Tiainen et al. [13] investigated cognitive performance of CA survivors at six months post arrest. Of 41 survivors, 34% had mild to moderate cognitive deficits and 17% had severe cognitive deficits. Cognitive deficits were predominantly detected in executive and memory functions [13]. Further research at one year concluded that a substantial number of patients had cognitive deficits, with memory being mostly affected in up to 64% [14]. Most recovery of deficits occurs in the first three months [10], [12], [14], [15]. Large heterogeneity between studies and differences in assessment instruments make it difficult to draw firm conclusions about the incidence of cognitive impairments and their time course after surviving CA, which emphasizes the necessity of the current study.

Besides cognitive impairments, subjective cognitive complaints can be present. Previous research has shown that at four weeks after CA 10 of 77 (13%) survivors had subjective cognitive complaints [16]. In this study, it is remarkable that the overlap between patients with cognitive impairments and those with cognitive complaints was limited (<30%), which raises questions about the relation between objective and subjective cognitive functioning. Another study used the Global Deterioration Scale to detect self-estimated cognitive deficits six months post arrest, with 56% of survivors rating themselves as having some degree of cognitive deficits [17]. At three years after CA, Wachelder et al. showed that 13 of 61 (21%) survivors had subjective cognitive complaints [18]. Research on patients with stroke and mild traumatic brain injury has shown no or only a mild correlation between cognitive complaints and cognitive impairments [19], [20]. To our knowledge this relationship has not been studied in CA survivors yet. Previous research shows that cognitive problems can negatively affect quality of life, participation and autonomy of survivors [5], [10], [15], [18], [21], [22].

In the present study the scope was twofold. The first goal was to examine cognitive impairments and subjective cognitive complaints and their course up to one year after CA. The second goal was to examine whether subjective cognitive complaints and objective cognitive impairments were associated.