Differentiating anxiety and depression symptoms in patients with partial epilepsy

Abstract

Anxiety and depression are separate psychiatric conditions that are often interrelated. This study examines whether they exist independently in this population of patients with partial epilepsy and if they affect all quality-of-life domains. Adult epilepsy patients taking two or more antiepileptic drugs completed a health status survey including demographic items, the Hospital Anxiety and Depression Scale, and the Quality of Life in Epilepsy—10 (QOLIE-10). The questionnaire was completed by 201 epilepsy patients. Symptom prevalences of anxiety (52% none, 25% mild, 16% moderate, 7% severe) and depression (62% none, 20% mild, 14% moderate, 4% severe) were high. All health-related quality-of-life (HRQOL) domains worsened significantly with increasing levels of anxiety and depression: Total QOLIE-10 scores decreased from 72 ± 18 in patients with no anxiety to 54 ± 13 in those with mild, 48 ± 18 in those with moderate, and 40 ± 23 in those with severe anxiety (P < 0.0001). Total QOLIE-10 scores decreased from 70 ± 16 in patients with no depression to 50 ± 16 in those with mild, 45 ± 16 in those with moderate, and 24 ± 21 in those with severe depression (P < 0.0001). No significant difference in anxiety scores was observed controlling for seizure frequency or epilepsy duration. Regression analyses showed that anxiety and depression account for different proportions of variance as predictors of HRQOL (R² = 0.337 (anxiety) and 0.511 (depression)). The data suggest that patients may benefit from increased attention to the role of anxiety separately from depression.

Introduction

Psychiatric comorbidities often occur among people with epilepsy. There is a growing body of evidence that the prevalence is substantial. A review of the literature through 1986 described a higher prevalence of behavioral/psychiatric problems among people with neurological disorders than people who were healthy or had nonneurological diagnoses [1]. The number of reports has increased in scope during the past two decades. Devinsky described psychosocial and behavioral dysfunction among epilepsy patients by type [2], while Trimble defined disturbances as ictal, or postictal, and interictal [3]. Most of these concepts can be referred back to the seminal work of Waxman and Geschwind [4] describing the concept of behavior changes beyond ictal events. Neuroimaging has allowed a closer look at the mechanism shared by epilepsy and mood disorders. Both involve the limbic system, with additional involvement of the prefrontal cortex in mood disorders [5].

The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) [6] describes major depression as well as minor affective disorders including depression (dysthymia) that may be chronic. Dysthymia is a low-grade depression encompassing the same features as major depression (depressed mood, weight or appetite change, sleep dysfunction, agitation or psychomotor retardation, guilt, lack of feeling pleasure/enjoyment). Blumer et al. noted that epilepsy patients often have an “interictal dysphoric” syndrome featuring irritability, mood swings, anxiety, and behavioral dyscontrol [7]. Some evidence exists that antidepressants are effective for this diagnosis [8]. The DSM-IV guideline for diagnosis of anxiety includes excitability and worry with restlessness, fatigue, reduced concentration, irritability, muscle tension, and sleep disturbance.

An extensive survey by Murphy et al. demonstrated a strong comorbidity between anxiety and depression [9]; however, although anxiety often was found in the absence of depression, the converse was not true for depression. They pointed out that anxiety is distinctly different and separate from depression based on symptomatology and physiological attributes: “The fearfulness, sweating, trembling, palpitations that subjects report when diagnosed as having an anxiety disorder are different from the sadness, loss of energy, sleep, and appetite that they report when diagnosed as depressed.” When a patient experiences both disorders, anxiety usually appears first, followed by chronic depression, with anxiety persisting if the depression resolves.

The extensive literature on psychiatric disturbances in epilepsy has focused largely on depression. A more detailed view of this concept suggests that people with epilepsy might also suffer greatly from anxiety disorders [10]. The sudden, unpredictable onset of seizures surely can cause anxiety. The fears of embarrassment, danger, and injury from a seizure could lead to a variety of anxiety disorders. Yet, neurologists are not known to evaluate patients for these likely comorbidities routinely, nor has this been a focus of neurological education. Anxiety is less well-studied as a comorbidity in epilepsy than depression, although it affects many patients [11]. Anxiety disorders often are assumed to be part of depression because of the close associations often seen between the two disorders. Acknowledging anxiety about seizures usually is considered a typical feature among epilepsy patients. Simple partial seizures and auras often include affective symptoms including anxiety. Thus, assessment of anxiety should not include peri-ictal feelings. Vasquez and Devinsky noted that anxiety and depression were more common in limbic epilepsy than idiopathic generalized epilepsy [12]. Their review found no studies on the treatment of anxiety among epilepsy patients. Similarly, a UK postal survey found that the prevalence of anxiety (approximately 25%) was less than the prevalence of depression (approximately 40%) [13] . Few detailed reports describe the prevalence of anxiety disorders either alone or concomitant with depression. Johnson et al. evaluated the independent effects of these two types of affective disorder in patients with temporal lobe epilepsy [14]. There is a need for a similar survey focused on anxiety.

We undertook a survey to look further at the influence of anxiety and depression, as well as clinical and demographic correlates, in patients with incomplete control of partial epilepsy. The study was designed to assess the prevalence and concurrence of anxiety and depression among people with active epilepsy using the Hospital Anxiety and Depression Scale (HADS) [15]. The advantage of the HADS is that it provides data for both anxiety and depression based on comparable scoring. This feature allows for comparison between levels of each component affective disorder.