Cardiovascular disease (CVD) affects nearly 83 million Americans [
Psychiatric comorbidity is also prevalent in persons with CVD with nearly one-fourth of patients with CVD reporting symptoms congruent with a depression diagnosis [
Similar to this high risk of depressive symptoms, recent work also suggests that CVD patients are at risk for apathy [
The prevalence of apathy in a CVD population has not been empirically examined. Based on the above findings, it is likely that apathy frequently occurs in persons with CVD and is associated with cognitive function [
Participants were recruited from outpatient cardiology clinics. Inclusion criteria required that participants speak English. Exclusion criteria included history of neurological disorder (e.g., dementia, stroke), moderate or severe head injury (defined as greater than 10 minutes loss of consciousness), past or current severe psychiatric illness (e.g., schizophrenia, bipolar disorder), past or current alcohol or drug abuse (as defined by Diagnostic and Statistical Manual of Mental Disorders 4th Edition (DSM-IV) criteria), and a history of learning disorder or developmental disability (as defined by DSM-IV criteria) [
Descriptive statistics for demographic, psychological, and medical information (
Demographic variables | |
Age, mean (SD) | 61.42 (11.55) |
Male (%) | 77.2 |
Psychological variables | |
BDI, mean (SD) | 4.44 (3.75) |
AES total, mean (SD) | 26.39 (6.52) |
Medical variables (% yes) | |
Coronary Artery Bypass Graft | 11.4 |
Type 2 diabetes | 17.1 |
Heart attack | 31.7 |
High cholesterol | 83.7 |
Heart failure | 5.7 |
High blood pressure | 69.1 |
METs, mean (SD) | 9.85 (3.09) |
The Apathy Evaluation Scale (AES) was developed as a method of measuring apathy related to brain pathology, in order to discriminate patients with apathy from those without and to distinguish depression from apathy. This measure is comprised of 18 questions on a 4-point Likert scale, thus resulting in scores from 1 to 4 for each item and total scores from 18 to 72, with higher scores representing greater levels of apathy. Internal consistency, test-retest, and interrater reliability indices are satisfactory and range to 0.94 [
Depression was assessed using the Beck Depression Inventory-II (BDI-II). The BDI-II is a check-list of depressive symptoms that demonstrates good psychometric properties in persons with medical conditions (i.e., test-retest reliability of
A brief neuropsychological battery was administered to all participants to assess current levels of cognitive function. All measures exhibit strong psychometric properties and they are commonly used in clinical practice and research. The following measures were administered to the participants in the current sample to assess global cognitive function, attention, executive function, memory, and visuospatial abilities: Modified Mini-Mental Status Exam (3MS) [ Trail Making Tests A and B (TMT A and B) [ Rey-Osterrieth Complex (Rey-O) Figure Test Copy and Delayed Recall [ Ruff 2 and 7 Test—The Automatic Detection Accuracy (ADA) and Controlled Search Accuracy (CSA) [
Metabolic equivalents (METs) is a stress test measure that estimates cardiac workload. METs were obtained from a standardized symptom limited volitional maximal treadmill stress test (GXT). The exercise protocol was comprised of an increase in mill elevation every 60 seconds that estimates a relative increase in workload of 15%, holding speed constant. Testing also utilized an increase in speed every 3 minutes that also reflects a relative increase in workload of 15% from the previous stage. The test was ended at the patient’s request, or if the patient showed clinical signs of cardiovascular, neurologic, or musculoskeletal distress. Peak exercise capacity was approximated from the treadmill speed, grade, and duration and was expressed as METs [
Demographic and medical characteristics were ascertained through self-report and corroborated by a medical record review.
All study methods were approved by the appropriate IRB approval and all participants provided written informed consent. Participants completed a brief assessment of apathy, depression, and cognitive functioning, including a cognitive battery and self-report measures. Cardiovascular fitness was assessed with an exercise stress test protocol, providing metabolic equivalents (METs) during maximal exercise. Finally, a medical chart review was conducted.
Pearson correlations were conducted to determine whether demographic and medical variables were correlated with apathy scores and to define possible covariates. Following this analysis, partial correlations controlling for demographic and medical variables that emerged as significant contributors to apathy were performed to examine the correlation between apathy scores and measures of cognitive function. Finally, Chi-square and independent sample
Overall, participants exhibited relatively preserved levels of cardiovascular fitness, as the sample had an average METs value of 9.85 (
Descriptive statistics and average
Mean | Standard deviation |
| |
---|---|---|---|
3MS | 95.15 | 4.38 | 56 |
TMT A | 32.29 | 9.46 | 53 |
TMT B | 83.63 | 38.85 | 48 |
Rey-O Copy | 27.75 | 5.25 | 43 |
Rey-O Recall | 13.39 | 6.05 | 49 |
Ruff ADA | 93.27 | 6.70 | 41 |
Ruff CSA | 90.60 | 7.10 | 43 |
Higher scores on the BDI-II were associated with higher total apathy scores (
Correlation between demographic, psychological, neuropsychological, and medical variables and apathy scores (
Total AES | Emotional AES | Behavioral AES | Cognitive AES | Other AES | |
---|---|---|---|---|---|
Age | 0.05 | 0.05 | −0.08 | 0.06 |
|
Gender | −0.12 | −0.14 | −0.05 | −0.11 |
|
Type 2 diabetes | 0.11 | 0.03 | 0.07 | 0.14 | 0.05 |
Heart attack | 0.17 | 0.11 | 0.07 | 0.20* | 0.14 |
Heart failure | −0.10 | −0.02 | −0.13 | −0.12 | −0.01 |
High cholesterol | 0.13 | 0.05 | 0.10 | 0.16 | 0.06 |
High blood pressure | 0.01 | −0.04 | −0.02 | 0.05 |
|
CABG | 0.03 | 0.09 | −0.04 | 0.04 | 0.03 |
METs | −0.16 | −0.12 | 0.00 | −0.20* | −0.14 |
BDI | 0.49** | 0.11 | 0.44** | 0.44** | 0.52** |
TMT A | 0.05 | 0.09 | 0.08 | 0.01 | 0.00 |
TMT B | 0.11 | 0.03 | 0.19* | 0.08 | 0.06 |
3MS | 0.08 | 0.11 | −0.02 | 0.16 | −0.09 |
Rey-O Copy | 0.05 | 0.07 | 0.01 | 0.06 | 0.02 |
Rey-O Delayed | 0.08 | 0.11 | 0.05 | 0.06 | 0.04 |
Ruff ADA | −0.06 | −0.02 | −0.07 | 0.02 | −0.19* |
Ruff CSA | −0.06 | −0.04 | −0.06 | −0.01 | −0.12 |
*
Partial correlations adjusting for cardiovascular fitness, BDI-II, and past history of heart attack revealed a significant association between the other apathy subscale score with Ruff ADA (
Given the low prevalence of apathy in the overall sample, exploratory analyses were conducted to determine potential group differences between those expressing apathy 1.5 standard deviations greater than the mean values from a sample of healthy older adults [
Comparison of low and high apathy groups on demographic, psychological, neuropsychological, and medical variables.
Test statistic |
| |
---|---|---|
Chi-squares | ||
Gender | 2.08 | 0.21 |
Heart attack | 1.54 | 0.28 |
Heart failure | 1.03 | 0.50 |
High cholesterol | 1.95 | 0.32 |
High blood pressure | 0.01 | 1.00 |
CABG | 0.00 | 1.00 |
|
||
Age | −0.67 | 0.51 |
METs | 1.02 | 0.31 |
TMT A | −1.95 | 0.06 |
TMT B | −1.58 | 0.12 |
3MS | −0.28 | 0.78 |
Rey-O Copy | −0.62 | 0.54 |
Rey-O Recall | −0.52 | 0.68 |
Ruff ADA | 0.77 | 0.44 |
Ruff CSA | 0.57 | 0.57 |
BDI-II | −6.15 | 0.001 |
Although the current study found that apathy was not prevalent in this sample of persons referred for cardiac testing, higher levels of apathy were associated with greater depression symptoms, a history of heart attack, and poorer cardiovascular fitness. In terms of cognitive function, apathy was correlated with poorer performance on tasks of speeded planning and sequencing and cancellation of visual stimuli. Several aspects of these findings warrant further discussion.
Average apathy scores in the current sample were lower than the proposed cut off score of 37 and above levels used in neurological samples [
Indeed, our findings suggest that CVD severity may offer an alternative explanation as poorer fitness and positive history of heart attack were associated with apathy. This pattern indicates that more severe levels of CVD are likely associated with higher levels of apathy. Further, individuals with more severe forms of CVD have shown more pervasive brain changes (i.e., gray matter loss) [
Consistent with expectations, depression scores were closely associated with apathy total and subscale scores. Depression and apathy share many features, frequently cooccur, and can result from structural changes in the brain [
Apathy was largely unrelated to cognitive test performance in the current study, which is contrary to past work in other medical populations. For example, one study found that apathy was associated with poorer performance on tasks measuring working memory, learning, and cognitive flexibility in HIV samples [
The current study was limited in several ways. The sample consisted of individuals being referred for evaluation of possible CVD and future studies should enroll participants with more severe CVD, particularly those with HF. This approach would likely produce a sample with higher apathy scores, more severe brain changes, and greater impairments on neuropsychological testing. Other related methodological changes would include selectively targeting older patients, those with known cognitive impairment, and/or CVD patients identified as having significant levels of apathy. Each of these approaches would minimize range restriction and promote understanding of apathy in CVD patients. Finally, the study was restricted to an apathy measure based solely on self-report, yet the addition of collateral report of apathy could enhance the current findings. Collateral report might provide additional insight into this population’s range of apathy levels.
In summary, low levels of apathy were observed in a sample of persons referred for cardiac testing and apathy was largely unrelated to cognitive function. Future research would benefit from utilizing an older population with more severe CVD to clarify the prevalence of and mechanisms for apathy in this population. Further, utilization of modern techniques assessing brain changes in the CVD population, such as functional MRI (fMRI) or diffusion tensor imaging (DTI), might provide additional insight into the proposed relationship between apathy and cognition in CVD patients. A better understanding of this phenomenon could provide helpful information to health care providers, patients, and those regularly caring for individuals with CVD.
The indirect support for this work included the National Institutes of Health (NIH) Grants DK0751169 and HLO89311.