Michael R. Trimble

The psychiatric comorbidity of epilepsy

Several studies have assessed the prevalence of psychiatric disorders in epilepsy. They are characterized by considerable heterogeneity, because of differences in the population setting and type of study. A non‐systematic review of the literature allows us to draw some useful, although not definite, conclusions. Six per cent of people with epilepsy in the general population appear to suffer from a psychiatric disorder, while this rises to 10–20% in populations with temporal lobe and/or refractory epilepsy. Mood disorders are the most common culprit (24–74%), particularly depression (30%), followed by anxiety disorders (10–25%), psychoses (2–7%) and personality disorders (1–2%). This comorbidity appears to be related to endogenous and exogenous (including iatrogenic) factors and to the severity and chronicity of epilepsy. Conditions such as schizophrenia‐like psychosis of epilepsy and interictal dysphoric disorder are represented only in epilepsy. Adequate recognition and treatment of psychiatric conditions in epilepsy is essential for patient management because of their considerable burden in morbidity and quality of life.

Activity in ventromedial prefrontal cortex covaries with sympathetic skin conductance level: a physiological account of a "default mode" of brain function

We examined neural activity related to modulation of skin conductance level (SCL), an index of sympathetic tone, using functional magnetic resonance imaging (fMRI) while subjects performed biofeedback arousal and relaxation tasks. Neural activity within the ventromedial prefrontal cortex (VMPFC) and the orbitofrontal cortex (OFC) covaried with skin conductance level (SCL), irrespective of task. Activity within striate and extrastriate cortices, anterior cingulate and insular cortices, thalamus, hypothalamus and lateral regions of prefrontal cortex reflected the rate of change in electrodermal activity, highlighting areas supporting transient skin conductance responses (SCRs). Successful performance of either biofeedback task (where SCL changed in the intended direction) was associated with enhanced activity in mid-OFC. The findings point to a dissociation between neural systems controlling basal sympathetic tone (SCL) and transient skin conductance responses (SCRs). The level of activity in VMPFC has been related to a default mode of brain function and our findings provide a physiological account of this state, indicating that activity within VMPFC and OFC reflects a dynamic between exteroceptive and interoceptive deployment of attention.

Brain activity relating to the contingent negative variation: an fMRI investigation

The contingent negative variation (CNV) is a long-latency electroencephalography (EEG) surface negative potential with cognitive and motor components, observed during response anticipation. CNV is an index of cortical arousal during orienting and attention, yet its functional neuroanatomical basis is poorly understood. We used functional magnetic resonance imaging (fMRI) with simultaneous EEG and recording of galvanic skin response (GSR) to investigate CNV-related central neural activity and its relationship to peripheral autonomic arousal. In a group analysis, blood oxygenation level dependent (BOLD) activity during the period of CNV generation was enhanced in thalamus, somatomotor cortex, bilateral midcingulate, supplementary motor, and insular cortices. Enhancement of CNV-related activity in anterior and midcingulate, SMA, and insular cortices was associated with decreases in peripheral sympathetic arousal. In a subset of subjects in whom we acquired simultaneous EEG and fMRI data, we observed activity in bilateral thalamus, anterior cingulate, and supplementary motor cortex that was modulated by trial-by-trial amplitude of CNV. These findings provide a likely functional neuroanatomical substrate for the CNV and demonstrate modulation of components of this neural circuitry by peripheral autonomic arousal. Moreover, these data suggest a mechanistic model whereby thalamocortical interactions regulate CNV amplitude.

Phenomenology of depression in epilepsy

Summary: Sixty‐six patients with epilepsy and depression were studied. Thirty‐four had a family history of psychiatric illness; depression was the most common condition. Assessed using standardised rating scales, the severity of the depression was moderate and was endogenous in –40% of patients. Attendant features were high state and trait anxiety and hostility. The EEGs of the patients and a control group were not significantly different. Patients receiving phenobarbital (PB) were more depressed, whereas those taking carbamazepine (CBZ) were both less depressed and less anxious. The phenomenology of the depression was not clearly influenced by epilepsy variables. We suggest that the depression in patients with epilepsy represents the outcome of multiple factors in genetically predisposed individuals.

Obsessions and compulsions in Gilles de la Tourette's syndrome

The incidence of obsessive-compulsive disorder (OCD) in patients with Gilles de la Tourettes syndrome (GTS) was assessed with a specially designed questionnaire. The Inventory was administered to patients with OCD, patients with GTS, and normal controls. Fifty-one percent of the patients with GTS had significantly elevated Inventory scores. The frequent occurrence of OCD in GTS suggests that the two disorders may share common neurobiologic mechanisms.

Psychiatric adverse events during levetiracetam therapy

The prevalence and psychopathologic features of psychiatric adverse events (PAE) in 517 patients taking levetiracetam (LEV) were investigated. Fifty-three (10.1%) patients developed PAE. A significant association was found with previous psychiatric history, history of febrile convulsions, and history of status epilepticus, whereas lamotrigine co-therapy had a protective effect. PAE were not related to the titration schedule of LEV, and certain patients seem to be biologically more vulnerable.

Anticonvulsant drugs and cognitive function: a review of the literature.

Summary: Alterations of cognitive function are separate from disturbances of behavior seen in association with epilepsy. The nature of the cognitive disability may to a certain extent depend on the seizure type. Partial seizures, mainly derived from a temporal lobe focus, impair memory tasks, while generalized seizures seem to have more effect on attentional abilities. A number of studies, reviewed in this paper, suggest that anticonvulsant drugs further impair cognitive function. Maximal impairments are seen in patients receiving polytherapy: rationalization of polytherapy improves cognitive abilities. Studies in children and adults have allowed differentiation of the effects of various commonly used antiepileptic agents. Maximal cognitive deficits are seen with. phenytoin, while phenobarbital and sodium valproate induce moderate disturbances, and carbamazepine seems relatively free from such toxicity. Further research is needed on the interrelationship between types of seizure disorders, types of anticonvulsant medications, and cognitive function.

Vigabatrin and psychosis.

We report a series of 14 cases of psychosis occurring in patients with severe intractable epilepsy, following the prescription of vigabatrin, a new antiepileptic drug. Nine patients had no previous history of psychosis. In eight patients the psychosis occurred following a change in the habitual pattern of seizure activity; in four it developed after a period of seizure freedom followed by a cluster of seizures, and in the other four patients an alternating psychosis was observed. In five patients there was no clear relationship to seizure pattern. Another patient developed psychosis after taking an overdose of between eight and 12 g of vigabatrin. A further three patients, who developed psychosis following vigabatrin withdrawal, were not included in this series. The mean dose at onset of the psychosis (excluding the patient who took an overdose) was 2580 mg, and the period from initiation of therapy to the onset of psychosis varied from five days to 32 weeks (and occurred 24 hours after the overdose of vigabatrin). In all cases the psychosis resolved, but necessitated the withdrawal of vigabatrin, except in the single patient who took the overdose. The mechanism of this behaviour change is unclear, but in some instances may reflect vigabatrins powerful anti-epileptic action. This is clearly not the case for all patients. Vigabatrin should be started with caution in patients with severe epilepsy, particularly in the presence of a previous history of psychosis, and such patients should be carefully monitored.

Depression and epilepsy: Epidemiologic and neurobiologic perspectives that may explain their high comorbid occurrence☆

Depression is the most frequent psychiatric comorbidity in people with epilepsy (PWE) with lifetime prevalence rates ranging between 30 and 35%. Multifactorial variables play a pathogenic role in the high comorbid occurrence of these two disorders. These variables were critically examined during an international symposium held in Chicago in September 2010, the results of which are presented in two companion manuscripts. The first manuscript summarizes new epidemiologic data highlighting the bidirectional relation between depression and epilepsy and related methodological issues in studying this relationship. An examination of the neurobiologic aspects of primary mood disorders, mood disorders in PWE and pathogenic mechanisms of epilepsy derived from studies in animal models and humans is allowing a better understanding of the complex relation between the two conditions. In the first manuscript, we review data from animal models of epilepsy in which equivalent symptoms of depression and anxiety disorders develop and, conversely, animal models of depression in which the kindling process is facilitated. Data from structural and functional neuroimaging studies in humans provide a further understanding of potential common pathogenic mechanisms operant in depression and epilepsy that may explain their high comorbidity. The negative impact of depression on the control of seizure disorders has been documented in various studies. In this manuscript, these data are reviewed and potential mechanisms explaining this phenomenon are proposed.

Topiramate and Psychiatric Adverse Events in Patients with Epilepsy

Summary:  Purpose: The aim of this study was to determine the prevalence of psychiatric adverse events (PAEs) in patients with epilepsy treated with topiramate (TPM). Classification, relation to TPM dosing, and outcome were evaluated to identify a patient profile at risk of developing PAEs.