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Med/Psych Update

How seizure disorders change depression treatment

Suicide risk is high in depressed patients with epilepsy, especially the temporal lobe form.

Vol. 7, No. 9 / September 2008

Ms. A, age 29, has had depression for 6 years and has taken antidepressants with inconsistent response. For 3 weeks, while not taking any antidepressant, she reports loss of energy; feeling sad, subdued, and tearful; poor concentration; and reduced interest in enjoyable activities including sex, the same symptoms she ?rst reported 6 years ago. She has no appetite but has not lost weight.

Several times a month Ms. A “loses” short periods of time. For example she says sometimes she cannot remember what happens between parking her car and sitting at her desk at work. After these episodes, which began 9 years ago, her speech is slightly slurred, and coworkers tease her about being “hungover.” She feels fuzzy-headed, but her speech and thinking clear after a few hours. At other times she smells burning rubber and feels that everything she does repeats what she has done before. Sometimes she feels “out of body” and can watch herself from the ceiling.

Ms. A’s symptoms suggest a seizure disorder. Her depressive features appeared after these ictal episodes began 9 years ago.

Recognizing mood disorders in patients with epilepsy is important because these disorders can be successfully treated within the context of the medical condition.

Many cases of comorbid depression in epilepsy are undiagnosed. A study of 100 patients with refractory epilepsy and depression severe enough for pharmacotherapy found that referral for psychiatric treatment was delayed >1 year in 75% of patients with spontaneous mood disorders and 89% of patients with depression secondary to antiepileptic drugs (AEDs).1

Psychiatrists often are called on to evaluate and treat depression in epilepsy patients or to assess for nonadherence to AEDs. Successfully treating these patients requires understanding:

  • the relationship between epilepsy and depression
  • the etiology of depression in patients with seizure disorder
  • how to treat depression in this population.

High comorbidity

Depression rates are higher in epilepsy patients than in the general population (1% to 3% of men, 2% to 9% of women).2 Depression can be diagnosed in:

  • 20% to 30% of patients with recurrent seizures
  • 6% to 9% of patients in remission
  • 50% to 55% of patients attending hospital epilepsy clinics and video telemetry units.3

Major depressive disorder is more common and severe in patients with a seizure disorder than in those with other neurologic and chronic medical conditions.4 Men with epilepsy have a higher risk of developing depression, whereas in the general population depression is more prevalent in women.5 Major depression may be more common in patients with complex partial seizures—specifically temporal lobe epilepsy (TLE), the most common form of epilepsy in adults.4 An estimated 3% to 21% of epileptic patients have dysthymic disorder.5 The prevalence of bipolar disorder in this population is unknown.

Temporal relationship. Depression can be preictal, ictal, postictal, or interictal.4 One-third of patients with partial seizures report premonitory symptoms, usually before secondary generalized tonic clonic seizures.5

  • Preictal depression occurs hours to days before a seizure and often is relieved by the convulsion.
  • Ictal depression—more common in TLE—occurs as an aura in approximately 1% of patients. Onset is sudden and ranges from mild sadness to profound helplessness and despair. Treating the seizures also treats the depression.
  • Postictal depression in TLE patients lasts hours to days after a seizure.
  • Interictal depression affects up to two-thirds of epilepsy patients, especially those with severe or frequent seizures. Treat interictal depression separately from the Seizures.

Differential diagnosis

Assessing and treating a depressive episode is similar in patients with or without epilepsy. In medically ill patients, DSM-IVTR recommends using diagnostic criteria for major depression and treating the depression whatever its cause.

Search for seizure cause. Although 70% of epilepsies are idiopathic, search for the cause of a patient’s seizures. Neuroimaging can rule out a stroke, cerebral tumor, or traumatic brain injury as the cause of both depression and epilepsy.4 Even after exhaustive study, 10% to 20% of epilepsy cases cannot be identified by electroencephalography (EEG).

Seizure type and location, severity, laterality of seizure focus, and frequency are important variables in the etiology of depression in patients with epilepsy.6 Similar changes in neurotransmitters—serotonin, noradrenaline, dopamine, and gamma-aminobutyric acid—are observed in both depression and epilepsy.5

Characterize depressive symptoms. Consider involving the patient’s spouse or partner in the discussion to validate and augment the patient’s report. Often patients describe depressive symptoms— such as sleep problems, changes in appetite, loss of libido, and impaired cognition—that could be side effects of AEDs or symptoms of epilepsy.

Depression associated with epilepsy has distinct features. Blumer7 coined the term interictal dysphoric disorder (IDD), characterized by these types of symptoms:

  • somatoform (anergia, pain, and insomnia)
  • affective (irritability, euphoric moods, fear, and anxiety).

The Neurological Disorders Depression Inventory for Epilepsy, an online, 6-item, self-assessment tool, can help identify a possible major depressive episode (see Related Resources).

Is it bipolar depression? Determine if your patient’s depression might be part of a bipolar disorder. This diagnosis may modify your treatment plan because antidepressants could trigger a manic or hypomanic episode. Also look for untreated psychotic features, which are associated with a suicide completion rate of 19% in bipolar epilepsy patients.6

Screen for suicidal behavior. Ask about suicidal ideation, plans, and attempts within the past month and in the patient’s lifetime.4 Compared with the general population, the risk of suicide is 4 to 5 times higher in depressed persons with epilepsy8 and 25 times higher in those with TLE (Table 1).9 Overdoses are used in 80% to 90% of suicide attempts among patients with epilepsy, perhaps because of the availability of AEDs.3

Perceived social stigma, inability to drive, AEDs’ effects on cognition, and interpersonal and psychosocial issues may contribute to the patient’s depression. Ask about social support, recent stressful events, and financial and vocational impact of the seizure disorder.6

Table 1

Risk factors for suicide among epilepsy patients

Age 25 to 49 years

Male gender

Coexisting psychopathology, including personality disorders

Temporal lobe epilepsy

Personal difficulties such as social or workrelated problems

Prolonged duration of epilepsy

Poor seizure control

Source: Reference 3

CASE CONTINUED: Searching for a cause

Previously Ms. A worked steadily and led an active life. She does not have a history of mania or hypomania. She is alert, neat, and cooperative. She sits calmly, gestures appropriately when speaking, and has no abnormal movements. She is subdued but says she is a bit anxious.

Her workup includes routine hematologic and biochemical parameters, EEG, and brain MRI. All are negative.

We look for signs of psychosis, mania, or personality disorder, which can affect the clinical presentation and influence diagnosis and management. Ms. A’s depressive episodes meet DSM-IV-TR criteria for nonmelancholic recurrent depression, but she has atypical features such as feeling “fuzzy-headed,” having slurred speech, and losing track of time.

Her episodes are sudden, brief, and involve altered awareness followed by amnesia. She describes déjà vu, perceptual changes, and motor speech problems.

Ms. A’s behavioral syndrome is consistent with complex partial seizure with frontal and temporal foci. Her dominant brain hemisphere likely is involved because speech is affected. We classify her depression as postictal because of the temporal relationship with the seizures. Thus, controlling the seizures should prevent the depression.

Depression as a side effect

Depression in epilepsy is multifactorial, and pharmacotherapy is one of many biologic and psychosocial risk factors.

AED’s negative effects such as depression and cognitive changes may be caused by polypharmacy, drug- induced folate deficiency, drug titration and dosage, or withdrawal.6 Patients receiving combination therapies are more likely to be depressed.4 AED polypharmacy might be a marker for refractory epilepsy, and thus depression can be caused by both the neurologic illness and its treatment. Shorvon et al10 reported improved alertness, concentration, drive, mood, and sociability after patients’ polytherapy was reduced to monotherapy, especially carbamazepine monotherapy.

Onset or worsening of depression could coincide with starting a new AED.6 Phenobarbital and topiramate are most closely associated with acute depression during initial treatment.3 One study noted that depressed patients taking barbiturates as part of polytherapy were significantly more depressed than those taking carbamazepine.8 Phenobarbital can produce depression, suicidal ideation, and suicidal and parasuicidal behavior.

Patients starting tiagabine might develop agitation, withdrawal, and mood disturbance that could suggest depression.3 With topiramate the rate of affective symptoms is dose-dependent, with an incidence of 9% with 200 mg/d and 19% with 1,000 mg/d.11

Some patients (11% to 15%) receiving polytherapy that includes liver enzyme -inducing AEDs (carbamazepine, oxcarbazepine, phenobarbital, phenytoin, primidone, and topiramate) present with decreased serum, erythrocyte, and cerebrospinal fluid folate levels, which is associated with depression.4

Bipolar depression. AEDs such as carbamazepine, valproic acid, and lamotrigine are used for bipolar maintenance therapy in patients without a seizure disorder. Lamotrigine is used to treat bipolar depression in non-epilepsy patients. Therefore, these AEDs are first-line treatment for comorbid epilepsy and bipolar depression.12

Using antidepressants

Effectively treating depression in epilepsy patients (Algorithm) encompasses assessment of prescribed AEDs and the use of antidepressants, electroconvulsive therapy (ECT), and psychotherapy. No evidence indicates that any 1 antidepressant is more effective than others for treating depression in patients with epilepsy. When starting an antidepressant, consider the drug’s effect on seizure threshold, its efficacy, and drug-drug interactions.

Seizure risk. Seizures are a rare but serious adverse effect of most antidepressants (Table 2).13 Compared with the incidence of first seizures in the general population (<0.1%), the prevalence of seizures occurring with therapeutic doses of antidepressant is increased (0.1% to 4%).4 Generalized tonic-clonic seizures are associated with increased mortality in tricyclic antidepressant (TCA) overdose, especially with amitriptyline, maprotiline, and clomipramine.

Desipramine, monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (SSRIs), and trazodone are preferred options for depressed epilepsy patients because these drugs lower the seizure threshold less than other antidepressants, with a 1% to 1.5% incidence of seizures during the first 2 years of treatment.14 Because most seizures reported with these medications are dose-related, blood level monitoring is helpful. Avoid bupropion, which has a seizure rate double that of other antidepressants.6

Clinical trial experience and EEG studies suggest that the SSRIs are less epileptogenic than TCAs. MAOIs also are less likely than TCAs to cause seizures but can cause excessive sedation when coadministered with barbiturates. The only double-blind trial of antidepressants (amitriptyline, nomifensine, and placebo) to treat comorbid depression and epilepsy found no significant differences among drugs or placebo.8

Drug-drug interactions. Consider the cytochrome P450 enzyme system when choosing an antidepressant for an epilepsy patient.6 Antidepressants can alter serum levels of phenobarbital and carbamazepine, and AEDs usually reduce antidepressant levels.8 For example, carbamazepine could lower TCA levels, valproic acid might elevate TCA levels,15 and imipramine and nortriptyline might increase phenytoin levels. Similarly, monitor TCA levels during AED withdrawal, as increased TCA concentrations can result in toxicity and concomitant behavioral effects.13

SSRIs may cause a dramatic rise in AED levels, leading to dizziness, ataxia, confusion, and somnolence. Sertraline and citalopram seem less likely to increase AED levels than fluvoxamine or fluoxetine.6 Fluvoxamine inhibits carbamazepine and phenytoin metabolism.3 Among SSRIs, most case reports of drug-drug interactions involve fluoxetine, which inhibits cytochrome enzymes and may increase carbamazepine or phenytoin levels, sometimes with clinical consequences.6 Monitor electrolytes when prescribing carbamazepine or oxcarbazepine with an SSRI because the combination may cause hyponatremia.

Start antidepressants at doses lower than used in patients without epilepsy, and gradually increase until depression remits. Periodically check AED levels during antidepressant treatment, and adjust dosages to maintain a therapeutic level.

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