Depression is the psychiatric condition most frequently identified in people with epilepsy. Nevertheless, it is very often unrecognized and untreated. It should be considered a serious problem because of its significant negative impact on the patient's quality of life and increased potential for self-injury or suicide. An important tool in understanding the variety of depressive syndromes in epilepsy is the timing of the mood symptoms in relation to the ictus:

Preictal symptoms of depression can appear hours to days before a seizure. This phenomenon has been well documented in studies utilizing rating scales for depression and associated symptoms before and after seizures. Patients typically report feelings of irritability, inability to experience any pleasure in activities, problems with concentration, and feelings of hopelessness. The intensity of these symptoms worsens over time. Symptoms usually remit after seizures, though in some patients symptoms may persist into the postictal period.

During the ictal phase, the mood may suddenly change to sadness, suicidal ideation or feeling of helplessness or hopelessness with no environmental precipitant. Symptoms of depression and fear are the two most common ictal expressions of psychiatric symptoms. Often they may be the only symptoms of the ictus, hence presenting as simple partial seizures. More often than not, however, these symptoms last less than 30 seconds and are followed by alteration of consciousness leading to a complex partial or secondarily generalized tonic-clonic seizure. Some investigators have suggested that the presence of psychiatric "auras" may be associated with a higher occurrence of interictal depressive disorders in patients with epilepsy.

Ictal crying (dacrystic seizures) is rare, despite the prevalence of unpleasant or dysphoric mood auras. Ictal laughing (gelastic seizures) is more common, yet the experience of euphoria during an ictus (a "Dostoyevskian seizure") is extremely rare. The divergence may represent an uncoupling of emotional experience from the expression of affect during the ictal phase.

During the postictal phase, symptoms of depression are common but often overlooked. In a recent study, 43% of 100 consecutive patients with intractable partial epilepsy experienced symptoms of depression after more than half of their seizures. The average duration of these symptoms was 24 hours, with a range from several minutes to up to a week. Of these 43 patients, 18 reported clusters of at least five symptoms of depression that lasted at least 24 hours and mimicked the symptoms of a major depressive episode, and 13 experienced suicidal thoughts. Most of the patients who reported symptoms of depression also reported symptoms of anxiety and disturbances in their sleep and appetite. Clearly, these symptoms have a greater impact in the life of patients than the actual seizure.

During the interictal phase, depression is the most frequent comorbid psychiatric disorder. Interictal depressive disorders result from a variety of factors including:

• chemical and electrophysiological changes in the brain resulting from the epileptic disorder itself
• a genetic predisposition to experience depression
  
• a reaction to the multiple obstacles faced by people with epilepsy
• an adverse effect of medications used to treat the seizures

The depressive disorders in people with epilepsy may be identical to those of people in the general population, but in up to 50% of people with epilepsy, interictal depressive episodes present features considered "atypical." Symptoms of irritability, poor frustration tolerance, and mood lability may be more prevalent and obvious than other symptoms typical of "classic" depression, such as inability to find pleasure in activities, problems with sleep and appetite, or feelings of helplessness and hopelessness. Their symptoms tend to last between a few hours and several days and may remit spontaneously for several days before recurring without any apparent reason. This on-off course of symptoms can persist for a very long time, to the point that patients and their families often consider these "mood changes" to be normal and "a part of the epilepsy." Thus, they fail to report them to the physician and the depressive episodes go untreated while having a significant taxing effect on the quality of life of the patients and their families.

Treatment of pre-ictal, ictal, and postictal symptoms of depression depends largely on seizure control. The efficacy of antidepressant drugs in treating postictal depressive episodes has not yet been evaluated.

On the other hand, patients with sustained episodes of interictal depression may benefit from antidepressants. These drugs seldom compromise seizure control in clinical practice.

Adapted from: Holzer JC and Bear DM. Psychiatric considerations in patients with epilepsy. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 131-148.
With permission from Elsevier (www.elsevier.com)
Reviewed and extensively revised April 2004 by Andres M. Kanner, M.D., epilepsy.com Editorial Board