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Inter-ictal bipolar disorder
The prevalence of this is low (<5%) and characterised by periods of depressed mood and
episodes of mania. Several case series have reported a preponderance of patients with
complex partial epilepsy, particularly with right-sided foci.

Inter-ictal psychosis
The prevalence is reported to be 410% in patients with epilepsy, mainly in those with
temporal lobe epilepsy7,8,9. It is a chronic disorder and clinically resembles chronic
schizophrenia (symptoms of delusions, hallucinations, thought disorder) but there are some
reports that personality is better preserved. The onset of the psychosis is variable but usually
occurs after many years of epilepsy (more than ten years). The risk factors that have been
reported are early age of onset of epilepsy, bilateral temporal foci and a refractory course. It
has been more commonly associated with left-sided epileptic focus10,11. The
pathophysiological mechanisms of psychosis in epilepsy are unclear and both focal and
generalised brain abnormalities have been implicated12-15.

Treatment with antipsychotic medications is usually long term. The atypical antipsychotic
drugs are potentially less likely to reduce seizure threshold (with the exception of clozapine)
or cause extrapyramidal side effects. Lower doses than those used in primary schizophrenia
seem to be effective. Psychosocial support and family education are also important.

Treatment-related psychiatric problems

Antiepileptic drugs
Some antiepileptic drugs (AEDs) can cause psychiatric problems, most commonly
depression, anxiety, behavioural or cognitive problems and, in rare cases, psychosis.
Phenobarbitone, primidone, tiagabine, topiramate, vigabatrin and felbamate have been
associated with depression. Psychosis is a rare complication of a number of AEDs such as
vigabatrin and topiramate.

Improved seizure control has been associated with the emergence of psychiatric symptoms.
Landolt introduced the term ‘forced normalisation’ which refers to a dramatic reduction in
epileptiform activity on EEG being associated with the emergence of psychosis or sometimes
behavioural/mood disturbances. This phenomenon has been reported with most AEDs and
therefore any new drug should be started at low doses and increased slowly. The risk may be
higher in patients who are on polytherapy, become seizure free abruptly, or if there is a past
psychiatric history.

Epilepsy surgery
Transient mood disturbances (emotional lability, depression and anxiety) have been reported
following temporal lobe surgery for epilepsy (about 25%) in the first 612 weeks16. However,
in some patients (10%), symptoms, particularly depression, may persist and require
psychiatric treatment. There are also reports of de novo inter-ictal psychosis arising after
surgery. It is therefore important for pre- and post-surgical psychiatric evaluation to form part
of the assessment/management for epilepsy surgery.

References

1. MARSH L, RAO V. Psychiatric complications in patients with epilepsy: a review. Epilepsy Res 2002; 49: 11-33.
2. KANNER AM, NIETO JC. Depressive disorders in epilepsy. Neurology 1999; 53: S26-S32.
3. KANNER AM, STAGNO S, KOTAGAL P, MORRIS HH. Postictal psychiatric events during prolonged video-

electroencephalographic monitoring studies. Arch Neurol 1996, 53: 258-263.
4. LOGSDAIL SJ, TOONE BK. Postictal psychoses: a clinical and phenomenological description. Br J Psych 1988;

152: 246-252.
5. ROBERTSON MM, TRIMBLE MR, TOWNSEND HRA. Phenomenology of depression in epilepsy. Epilepsia

1987; 28: 364-368.