Atypical antipsychotics and serotoninergic antidepressants in patients with epilepsy: pharmacodynamic considerations

Risk of seizures associated with antipsychotic treatment in pediatrics with psychiatric disorders: a nested case-control study in Korea

Antipsychotic drugs raise seizure risk in adults, and antipsychotic drug use is increasing among pediatric psychiatric disorder patients. However, few studies have examined seizure risk in this younger patient population. To evaluate seizure risk in pediatric patients on antipsychotics, we conducted a nested case-control study using a nationwide database. Patient information was retrieved from the Korean Health Insurance Review and Assessment (HIRA) database from 2008-2018. Antipsychotic use among newly diagnosed psychiatric patients was gathered starting 1 year before the index date and categorized as recent, past, consistent, or none. Seizure cases among these patients were defined based on (1) prescription of antiepileptic drugs or (2) an electroencephalography (EEG) examination among patients with seizure diagnostic code. A conditional logistic regression model was constructed to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for seizure risk due to antipsychotic use. In total, 1523 seizure cases and 6092 seizure-free controls aged 8-19 years with newly diagnosed psychiatric disorders were included for analysis. Logistic regression revealed a significant association between antipsychotic use and seizure development (recent users OR = 4.03, 95% CI 3.4-4.79; consistent users: OR = 2.84, 95% CI 2.44-3.3). Seizure risk enhanced further with an increase in the number of antipsychotic drugs used. Risperidone, aripiprazole, quetiapine, olanzapine, paliperidone, and blonanserin were independently associated with greater seizure risk. Pediatric patients receiving antipsychotics, especially new or multiple antipsychotic users, should be carefully monitored for seizure development.

Modulatory Effect of Serotonergic System in Pentylenetetrazole-Induced Seizures and Associated Memory Deficit: Role of 5-HT1A and 5-HT2A/2C

Background and Purpose

Recent studies have recognised the memory deficit as one of the most common psychiatric issues in the patients with epilepsy, which severely affects the quality of life. Our previous studies have demonstrated the possible involvement of serotonergic system in the pathogenesis of epilepsy and associated memory deficit. The possible involvement of 5-HT_1A and 5-HT_2A/2C receptor has not been explored yet. Therefore, this study has been envisaged to explore the effect of 5-HT_1A and 5-HT_2A/2C receptor modulation on epilepsy and memory deficit in pentylenetetrazole-kindled mice.

Methods

In the present experimental approach, we examined the efficacy of modulation of 5-HT_1A and 5-HT_2A/2C receptor in pentylenetetrazole-induced kindling in male Swiss mice (n=75). Mice were kindled by sub-convulsive dose of pentylenetetrazole (35 mg/kg, intraperitoneal injection), at the interval of 48±2 hours). Successfully kindled animals were treated with 5-HT_1A and 5-HT_2A/2C receptor modulators. The effect of different treatments on seizure severity score and memory impairment was analysed.

Results

5-HT_1A receptor agonist improved the memory functions while seizure severity was not improved, and the opposite effect was observed with 5-HT_1A receptor antagonist. On the other hand, 5-HT_2A/2C receptor agonist significantly improved memory deficit as well as seizure severity in the kindled animals.

Conclusions

The outcome of the study indicates the possible involvement of 5-HT_2A/2C receptor in the pathogenesis of epilepsy and associated memory deficit, which can be further explored for its management.

Do in vitro assays in rat primary neurons predict drug-induced seizure liability in humans?

Drug-induced seizures contribute to the high attrition rate of pharmaceutical compounds in development. The assessment of drug-induced seizure liability generally occurs in later phases of development using low throughput and intensive in vivo assays. In the present study, we evaluated the potential of an in vitro assay for detecting drug-induced seizure risk compared to evaluation in rats in vivo. We investigated the effects of 8 reference drugs with a known seizurogenic risk using micro-electrode array (MEA) recordings from freshly-dissociated rat primary neurons cultured on 48-well dishes for 28 days, compared to their effects on the EEG in anesthetized rats. In addition, we evaluated functional responses and mRNA expression levels of different receptors in vitro to understand the potential mechanisms of drug-induced seizure risk. Combining the functional MEA in vitro data with concomitant gene expression allowed us to identify several potential molecular targets that might explain the drug-induced seizures occurring in both rats and humans. Our data 1) demonstrate the utility of a group of MEA parameters for detecting potential drug-induced seizure risk in vitro; 2) suggest that an in vitro MEA assay with rat primary neurons may have advantages over an in vivo rat model; and 3) identify potential mechanisms for the discordance between rat assays and human seizure risk for certain seizurogenic drugs.

Effects of Psychotropic Drugs on Seizure Threshold during Electroconvulsive Therapy

OBJECTIVE

To analyze the relationship between seizure threshold (ST) and psychotropic drugs in patients treated with ECT.

METHODS

We examined clinical data from 43 patients. ST was titrated at each treatment session. We examined associations between ST and psychotropic drugs using multivariate correlation analyses. Data are presented as initial ST, the difference in ST between the first and 10th sessions (ΔST_10th), and the mean difference in ST between the first and last sessions (mean ΔST_last).

RESULTS

Multivariate regression analyses showed associations between initial ST and the total chlorpromazine-equivalent dose of antipsychotics (β=0.363, p<0.05). The total fluoxetine-equivalent dose of antidepressants was associated with ΔST_10th (β=0.486, p<0.01) and mean ΔST_last (β=0.472, p<0.01).

CONCLUSION

Our study elucidated possible effects of psychotropic drugs on ST shifts. Larger doses of antipsychotics were associated with higher initial ST, whereas higher doses of antidepressants were associated with stronger shifts in ST.

Altered sleep regulation in a mouse model of SCN1A-derived genetic epilepsy with febrile seizures plus (GEFS+)

PURPOSE

Mutations in the voltage-gated sodium channel (VGSC) gene SCN1A are responsible for a number of epilepsy disorders, including genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome. In addition to seizures, patients with SCN1A mutations often experience sleep abnormalities, suggesting that SCN1A may also play a role in the neuronal pathways involved in the regulation of sleep. However, to date, a role for SCN1A in the regulation of sleep architecture has not been directly examined. To fill this gap, we tested the hypothesis that SCN1A contributes to the regulation of sleep architecture, and by extension, that SCN1A dysfunction contributes to the sleep abnormalities observed in patients with SCN1A mutations.

METHODS

Using immunohistochemistry we first examined the expression of mouse Scn1a in regions of the mouse brain that are known to be involved in seizure generation and sleep regulation. Next, we performed detailed analysis of sleep and wake electroencephalography (EEG) patterns during 48 continuous hours of baseline recordings in a knock-in mouse line that expresses the human SCN1A GEFS+ mutation R1648H (RH mutants). We also characterized the sleep-wake pattern following 6 h of sleep deprivation.

KEY FINDINGS

Immunohistochemistry revealed broad expression of Scn1a in the neocortex, hippocampus, hypothalamus, thalamic reticular nuclei, dorsal raphe nuclei, pedunculopontine, and laterodorsal tegmental nuclei. Co-localization between Scn1a immunoreactivity and critical cell types within these regions was also observed. EEG analysis under baseline conditions revealed increased wakefulness and reduced non-rapid eye movement (NREM) and rapid eye movement (REM) sleep amounts during the dark phase in the RH mutants, suggesting a sleep deficit. Nevertheless, the mutants exhibited levels of NREM and REM sleep that were generally similar to wild-type littermates during the recovery period following 6 h of sleep deprivation.

SIGNIFICANCE

These results establish a direct role for SCN1A in the regulation of sleep and suggest that patients with SCN1A mutations may experience chronic alterations in sleep, potentially leading to negative outcomes over time. In addition, the expression of Scn1a in specific cell types/brain regions that are known to play critical roles in seizure generation and sleep now provides a mechanistic basis for the clinical features (seizures and sleep abnormalities) associated with human SCN1A mutations.

Interactions between antiepileptics and second-generation antipsychotics

INTRODUCTION

Pharmacokinetic and pharmacodynamic drug interactions (DIs) can occur between antiepileptics (AEDs) and second-generation antipsychotics (SGAPs). Some AED and SGAP pharmacodynamic mechanisms are poorly understood. AED-SGAP combinations are used for treating comorbid illnesses or increasing efficacy, particularly in bipolar disorder.

AREAS COVERED

This article provides a comprehensive review of the interactions between antiepileptics and second-generation antipsychotics. The authors cover pharmacokinetic AED-SGAP DI studies, the newest drug pharmacokinetics in addition to the limited pharmacodynamic DI studies.

EXPERT OPINION

Dosing correction factors and measuring SGAP levels can help to compensate for the inductive properties of carbamazepine, phenytoin, phenobarbital and primidone. Further studies are needed to establish the clinical relevance of combining: i) AED strong inducers with amisulpride, asenapine, iloperidone, lurasidone and paliperidone; ii) valproate with aripiprazole, asenapine, clozapine and olanzapine; iii) high doses of oxcarbazepine (≥ 1500 mg/day) or topiramate (≥ 400 mg/day) with aripiprazole, lurasidone, quetiapine, risperidone, asenapine and olanzapine. Two pharmacodynamic DIs are beneficial: i) valproate-SGAP combinations may have additive effects in bipolar disorder, ii) combining topiramate or zonisamide with SGAPs may decrease weight gain. Three pharmacodynamic DIs contributing to decreased safety are common: sedation, weight gain and swallowing disturbances. A few AED-SGAP combinations may increase risk for osteoporosis or nausea. Three potentially lethal but rare pharmacodynamic DIs include pancreatitis, agranulocytosis/leukopenia and heat stroke. The authors believe that collaboration is needed from drug agencies and pharmaceutical companies, the clinicians using these combinations, researchers with expertise in meta-analyses, grant agencies, pharmacoepidemiologists and DI pharmacologists for future progression in this field.

Striking differences in proconvulsant-induced alterations of seizure threshold in two rat models

During drug development, seizure threshold tests are widely used to identify potential proconvulsant activity of investigational drugs. The most commonly used tests in this respect are the timed intravenous pentylenetetrazole (PTZ) infusion seizure test and the maximal electroshock seizure threshold (MEST) test in mice or rats. To our knowledge, no study is available in which proconvulsant drug activities in these models are directly compared, which prompted us to perform such experiments in male Wistar rats. Five drugs with reported proconvulsant activity were tested in the two models: d-amphetamine, chlorpromazine, caffeine, theophylline, and tramadol. Furthermore, the anticonvulsant drug phenobarbital was included in the experiments. While phenobarbital exerted anticonvulsant activity in both models, the five proconvulsant drugs markedly differed in their effects. In the dose range tested, d-amphetamine significantly lowered the PTZ seizure threshold but increased the MEST, caffeine and theophylline did not alter the PTZ seizure threshold but decreased the MEST, and tramadol reduced the PTZ threshold but increased the MEST. These marked differences between seizure threshold tests are most likely a consequence of the mechanisms underlying seizure induction in these tests. Our data indicate that using only one seizure threshold model during preclinical drug development may pose the risk that potential proconvulsant activity of an investigational drug is overseen. However, the label "proconvulsant" may be misleading if such activity only occurs at doses high above the therapeutic range, but the drug is not proconvulsant or even exerts anticonvulsant effects at lower, therapeutically relevant doses.

Epilepsy as a spectrum disorder: Implications from novel clinical and basic neuroscience

Epilepsy is increasingly recognized as a disease that reaches well beyond seizures. Cognitive and psychiatric impairment affect half of all epilepsy patients, and to date there are no specific treatments for these symptoms. It is unclear which of these comorbidities are directly due to seizures and which are due to separable mechanisms that are parallel to those underlying ictal activity. Cellular and molecular mechanisms underlying synaptic modulation are central to both the ictal and nonictal changes in epilepsy. Current diagnostic methods are rapidly advancing to better delineate the nature and extent of ictal activity, and could soon be critical in identifying patterns unique to the cognitive and psychiatric comorbidities.

A Case of Treatment Resistant Depression and Alcohol Abuse in a Person with Mental Retardation: Response to Aripiprazole and Fluvoxamine Therapy upon Consideration of a Bipolar Diathesis after Repetitive Failure to Respond to Multiple Antidepressant Trials

Mental Retardation (MR) is a developmental disability characterized by impairments in adaptive daily life skills and difficulties in social and interpersonal functioning. Since multiple causes may contribute to MR, associated clinical pictures may vary accordingly. Nevertheless, when psychiatric disorders as Treatment Resistant Depression (TRD) and/or alcohol abuse co-exist, their proper detection and management is often troublesome, essentially due to a limited vocabulary MR people could use to describe their symptoms, feelings and concerns, and the lack of reliable screening tools. Furthermore, MR people are among the most medicated subjects, with (over) prescription of antidepressants and/or typical antipsychotics being the rule rather than exception. Thus, treatment resistance or even worsening of depression, constitute frequent occurrences. This report describes the case of a person with MR who failed to respond to repetitive trials of antidepressant monotherapies, finally recovering using aripiprazole to fluvoxamine augmentation upon consideration of a putative bipolar diathesis for “agitated” TRD. Although further controlled investigations are needed to assess a putative bipolar diathesis in some cases of MR associated to TRD, prudence is advised in the long-term prescription of antidepressant monotherapies in such conditions.

Drug treatment-related factors of inadequate seizure control

To optimize seizure control it is important to identify modifiable factors. We conducted a case-control study to explore to what extent drug treatment-related factors are associated with seizures. Eighty-six patients with epilepsy were evaluated: 45 cases (recently experienced a seizure) and 41 controls (seizure-free for at least 2 months). There was a significant association between low AED serum concentration and seizures (odds ratio (OR)=8.9, 95% confidence interval (CI)=1.7-47.8), compliance was not associated with seizures (OR=0.9, 95% CI=0.2-4.0), and changes in medication (mainly non-AEDs) were more frequently observed in the case group than in the control group (OR=4.1, 95% CI=0.9-18.3). These findings indicate that patients with low AED serum levels have a nine times higher risk of seizures compared with patients with therapeutic AED levels and that changes in medication regimens in patients with epilepsy should be made with care.

Changes in medication associated with epilepsy-related hospitalisation: a case-crossover study

AIM

To assess the association between changes in medication and epilepsy-related hospitalisation.

METHODS

Data were obtained from the PHARMO Record Linkage System (Jan 1998 to Dec 2002). We conducted a case-crossover study among patients with a first epilepsy-related hospital admission who had continuously used at least one antiepileptic drug (AED) during a 28-week period before admission. For each patient, changes in medication in a 28-day window before hospitalisation were compared with changes in four earlier 28-day windows. Evaluated changes were: changes in AEDs (pattern and dosage), changes in interacting co-medication and changes in non-interacting co-medication (i.e. introduction of non-interacting drugs). The strength of the association between changes in medication and epilepsy-related hospitalisation was estimated using conditional logistic regression analysis and expressed as odds ratios (ORs) with 95% confidence intervals (CI).

RESULTS

Out of 1185 patients with a first epilepsy-related hospitalisation, 217 patients met the inclusion criteria. Of the changes in antiepileptic therapy, discontinuation showed a trend towards an increased risk of hospitalisation (OR: 2.57; 95%CI: 0.81-8.17). Drug interactions influencing antiepileptic therapy rarely occurred. Introduction of three or more non-interacting drugs was significantly associated with epilepsy-related hospitalisation (OR: 4.80; 95%CI: 2.12-10.87). Of individual drugs, addition of antimicrobial agents was significantly associated with epilepsy-related hospitalisation (OR: 1.99; 95%CI: 1.06-3.75).

CONCLUSIONS

Changes in AED therapy were not significantly associated with epilepsy-related hospitalisation and few drug interactions influencing antiepileptic therapy occurred. However, patients starting three or more new non-AEDs had a nearly five times increased risk of epilepsy-related hospital admission.

Transient nonketotic hyperglycinemia and defective serotonin metabolism in a child with neonatal seizures

Neonatal nonketotic hyperglycinemia is usually fatal or, less commonly, severely developmentally disabling, whereas transient nonketotic hyperglycinemia has usually been followed by normal development. We report a boy who had transient neonatal nonketotic hyperglycinemia but a coexistent disorder of serotonin metabolism manifested by initially low cerebrospinal fluid 5-hydroxyindoleacetic acid (which later normalized), low whole blood serotonin, and decreased platelet serotonin uptake. He survived the neonatal period but was neurodevelopmentally delayed and developed an autistic-like disorder. Later, his positron emission tomographic (PET) scans with alpha[(11)C] methyl-l-tryptophan revealed a pattern characteristic of autistic children. Although we know of no link between glycine and serotonin metabolism, and our patient had low, rather than high, central and peripheral serotonin, this case might represent a novel infantile disorder that affects both the glycine and serotonin neurotransmitter systems.

Behavioral and antiepileptic effect of acute administration of the extract of the aquatic plant Echinodorus berteroi (Sprengel) Fassett (upright burhead)

Echinodorus berteroi is an aquatic plant found in Central America and the Caribbean to which antiepileptic action has been attributed by folk medicine. The aim of the present study was to investigate the potential behavioral and antiepileptic effect of decoctions (1, 5, and 30%, intraperitoneally) of the dried roots. One and five percent decoctions produced hypoactivity in mice. Hyperactivity induced by amphetamine (3mg/kg, subcutaneously) was significantly reduced by the 30% decoction, in rats. The extracts did not modify the latency to the first clonic convulsion or the survival time of isoniazid (210 mg/kg, ip)-treated mice. The 30% decoction significantly increased the latency to the first picrotoxin-induced clonic convulsion (7 mg/kg, intraperitoneally), as well as survival time. Repeated administration of the 5% decoction (30-minute intervals) significantly reduced the amplitude (muV) of the epileptic spikes induced by topical application of penicillin to sensorimotor cortex, in curare-treated rats. In summary, the root decoctions of E. berteroi paradoxically exhibited neuroleptic and antiepileptic actions. Nevertheless, these results partly justify the use of the plant for the treatment of epilepsy by practitioners of folk medicine.

The alkaloid alstonine: a review of its pharmacological properties

Indole compounds, related to the metabolism of tryptophan, constitute an extensive family, and are found in bacteria, plants and animals. Indolic compounds possess significant and complex physiological roles, and especially indole alkaloids have historically constituted a class of major importance in the development of new plant derived drugs. The indole alkaloid alstonine has been identified as the major component of a plant-based remedy, used in Nigeria to treat mental illnesses by traditional psychiatrists. Although it is certainly difficult to compare the very concept of mental disorders in different cultures, the traditional use of alstonine is remarkably compatible with its profile in experimental animals. Even though alstonine in mice models shows a psychopharmacological profile closer to the newer atypical antipsychotic agents, it also shows important differences and what seems to be an exclusive mechanism of action, not entirely clarified at this point. Considering the seemingly unique mode of action of alstonine and that its traditional use can be viewed as indicative of bioavailability and safety, this review focuses on the effects of alstonine in the central nervous system, particularly on its unique profile as an antipsychotic agent. We suggest that a thorough understanding of traditional medical concepts of health and disease in general and traditional medical practices in particular, can lead to true innovation in paradigms of drug action and development. Overall, the study of this unique indole alkaloid may be considered as another example of the richness of medicinal plants and traditional medical systems in the discovery of new prototypic drugs.

Previous exposure to (±) 3,4-methylenedioxymethamphetamine produces long-lasting alteration in limbic brain excitability measured by electroencephalogram spectrum analysis, brain metabolism and seizure susceptibility

Seizures represent the most common neurological emergency in ecstasy abusers; however, no study addressed whether (+/-) 3,4-methylenedioxymethamphetamine ("ecstasy") per se might produce long-lasting alterations in brain excitability related to a pro-convulsant effect. C57 Black mice were treated with three regimens of (+/-) 3,4-methylenedioxymethamphetamine (5mg/kg x 2 for 1, 2 or three consecutive days). Following the last dose of (+/-) 3,4-methylenedioxymethamphetamine, during a time interval of 8 weeks, the following procedures were carried out: 1) cortical electroencephalographic recordings, including power-spectrum analysis; 2) administration of sub-threshold doses of kainate; 3) measurement of regional [(14)C]2-deoxyglucose uptake; 4) monoamine assay. We demonstrate that all mice pre-treated with (+/-) 3,4-methylenedioxymethamphetamine showed long-lasting encephalographic changes with frequencies peaking at 3-4.5 Hz at the power-spectrum analysis. This is concomitant with latent brain hyperexcitability within selected limbic brain regions, as shown by seizure facilitation and long-lasting latent metabolic hyperactivity which can be unraveled by phasic glutamate stimulation. This study sheds new light into the brain targets of (+/-) 3,4-methylenedioxymethamphetamine and discloses the occurrence of (+/-) 3,4-methylenedioxymethamphetamine-induced latent hyperexcitability within limbic areas, while it might provide a model to study in controlled experimental conditions limbic seizures and status epilepticus in C57 Black mice. Persistent changes produced by (+/-) 3,4-methylenedioxymethamphetamine in limbic brain excitability might be responsible for seizures and limbic-related disorders in chronic (+/-) 3,4-methylenedioxymethamphetamine abusers.

Epilepsy and psychiatry: Automatic psychic paroxysms

This study analyzes diverse psychic phenomena which, although always occurring with very characteristic clinical features, are sometimes diagnosed as epilepsy and sometimes as symptoms of different psychiatric disorders depending on the availability of an electroencephalogram. It is posited that these phenomena, whenever they are accompanied by the features characteristic of an epileptic consciousness (suddenness, automatic nature, great intensity and a strong sensation of strangeness) should be diagnosed as partial seizures with a psychic content, regardless of the availability of an EEG. The co-occurrence of these four clinical signs, which are relatively simple to objectivize, is a more reliable clinical criterion for diagnosis than a transcraneal electroencephalogram, which, as is known, is of little value in measuring the electrical activity of partial seizures. Moreover, an interpretation of this type makes it possible to reconcile scientific data from various neurosciences which thus far have seemed contradictory.

Lack of pro-convulsant activity of the antipsychotic alkaloid alstonine

Psychiatry co-morbidity with epilepsy is common and often requires the combined use of psychotropic and antiepileptic drugs (AEDs). For schizophrenic patients, the occurrence of seizures with atypical agents is highest among antipsychotics, although these agents are more effective in alleviating symptoms (including negative symptoms) and are associated with fewer extrapiramidal effects. The indol alkaloid alstonine is the major component of plants used by traditional Nigerian psychiatrists as anti-dementia drugs. The alkaloid presents an experimental profile very similar to the atypical antipsychotic clozapine. This study aimed to compare the pro-convulsant activity of these two antipsychotic compounds. Through repetitive administration over a 30-day period in a kindling paradigm, it is shown that, unlike clozapine, alstonine does not possess pro-convulsant activity. The data adds to previous suggestions that alstonine deserves to be scrutinized as a model for the development of newer antipsychotics.

[Pharmacological treatment of psychosis in epilepsy]

Epilepsy is one of the main causes of functional disability, and it is usually associated to psychiatric comorbidity, such as psychosis of epilepsy (POE). POE requires more careful pharmacological treatment, considering the propensity of the antipsychotics (AP) to provoke seizures and the risk of pharmacokinetic interaction with anti-epileptic drugs (AEDs). We discussed the classification and the main types of POE, as well as some characteristics of AP typical and atypical, its potential to decrease the epileptogenic threshold (ET) and possible interactions between AP and AED. Atypical AP, except clozapine, disclosed smaller influence on ET than typical AP. Regarding pharmacokinetic interactions, AEDs are related with a significant increase of the AP metabolism. Therefore, in spite of the risk for AP induced convulsions be dose-dependent, higher doses of AP can be necessary in the treatment of POE.

The importance of being seizure free: topiramate and psychopathology in epilepsy

The aim of this study was to analyze in detail psychopathology associated with topiramate (TPM) prescription and to analyze the relationship between psychopathology and seizure freedom. We analyzed the data on 103 patients who developed psychiatric disorders during TPM therapy. Forty-six patients developed an affective disorder, 22 aggressive behavior, 16 psychosis, 11 anxiety, and 8 personality changes such as anger, agitation, and hostile behavior. Patients with psychosis were more likely to be seizure-free during psychopathology, to receive psychotropic drug prescription, and to be admitted to hospital. In general, patients seizure-free during psychopathology were more likely to have a diagnosis of idiopathic generalized epilepsy, to be in co-therapy with vigabatrin, and to remit after drug reduction. We observed that psychopathology was related to seizure control in a subgroup of patients. The role of forced normalization, interlinked with interactions with other antiepileptic drugs, could be relevant.

Suicide in Neurologic Illness

The risk of attempted or completed suicide is increased in patients with migraine with aura, epilepsy, stroke, multiple sclerosis, traumatic brain injury, and Huntington's disease. Contrary to the general perception that the risk of suicide among patients with Alzheimer's disease and other dementing conditions is low, several reports suggest that the risk of suicide in these patients increases relative to the general population. Some patients at risk for neurologic disorders are also at increased risk for suicide; in particular, the risk of suicide is increased among persons at risk for Huntington's disease, independent of the presence or absence of the Huntington's gene mutation. The risk of attempted or completed suicide in neurologic illness is strongly associated with depression, feelings of hopelessness or helplessness, and social isolation. Additional suicide risk factors in persons with neurologic illness include cognitive impairment, relatively younger age (under 60 years), moderate physical disability, recent onset or change in illness, a lack of future plans or perceived meaning in life, recent losses (personal, occupational, or financial), and prior history of psychiatric illness or suicidal behavior. Substance dependence, psychotic disorders, anxiety disorders, and some personality disorders (eg, borderline personality disorder) may also contribute to increased risk of suicide among persons with neurologic illnesses. Identification and aggressive treatment of psychiatric problems, especially depression, as well as reduction of modifiable suicide risk factors among patients with neurologic illness is needed to reduce the risk of attempted and completed suicide in this population.