Pramipexole to Improve Cognition in Bipolar Disorder: A Randomized Controlled Trial.

BACKGROUND: Adults with bipolar disorder (BD) often experience neurocognitive impairment that negatively impacts functioning and quality of life. Previous trials have found that dopamine agonist agents improve cognition in healthy volunteers and that adults with BD who have stable mood and mild cognitive deficits may also benefit. We hypothesized that pramipexole, a dopamine agonist, would improve neurocognitive function in patients with BD. METHODS: We recruited 60 adults (aged 18-65 years) with a diagnosis of BD I or II for an 8-week, double-blind, placebo-controlled trial (NCT02397837). All had stable mood and clinically significant neurocognitive impairment at baseline. Participants were randomized to receive pramipexole (n = 31) or a placebo (n = 29), dose was initiated at 0.125 mg 2 times a day and increased to a target of 4.5 mg/d. RESULTS: At trial end, the primary outcome, MATRICS Consensus Cognitive Battery composite score, had not improved more in the pramipexole group (mean [SD] = 1.15 [5.4]) than in the placebo group (mean [SD] = 4.12 [5.2], Cohen's d = 0.56, P = 0.049), and mixed models, controlling for symptoms, showed no association between treatment group and MATRICS Consensus Cognitive Battery scores. No serious adverse events were reported. CONCLUSIONS: These results suggest that pramipexole is not an efficacious cognitive enhancement agent in BD, even in a sample enriched for characteristics that were associated with a beneficial response in prior work. There are distinct cognitive subgroups among adults with BD and may be related differences in neurobiology that affect response to pramipexole. Additional research to better understand the onset and nature of the cognitive deficits in people with BD will be an important step toward a more personalized approach to treatment.

Electroconvulsive Therapy and Schizophrenia: A Systematic Review.

Electroconvulsive therapy (ECT) is a remarkably effective treatment for major depressive disorder, but is less commonly utilized for treatment of psychotic disorders. Recent literature indicates that ECT can be a useful strategy for a wide range of psychotic disorders, including treatment-resistant schizophrenia. The purpose of this review is to examine the extant literature on ECT in schizophrenia with a primary focus on its efficacy, its impact on cognitive function, the role of maintenance ECT, and the potential role of neuroimaging biomarkers to provide more precise ECT treatment strategies. We evaluated the available literature, with a particular focus on prospective, randomized trials. Our review suggests that ECT can be an effective treatment strategy in this severely ill patient population. Studies suggest that while ECT in schizophrenia is a safe treatment modality, the potential for cognitive impairment must always be carefully weighed. The use and investigation of new biomarker strategies for the pharmacological treatment of schizophrenia, and the extension of these approaches to ECT are also discussed.

Continuation Electroconvulsive Therapy for Patients With Clozapine-Resistant Schizophrenia: A Pilot Study.

OBJECTIVES: The risk of relapse after a successful acute course of treatment is a clinical challenge in electroconvulsive therapy (ECT) practice, particularly in patients with a history of marked resistance to previous treatments. Research suggests that a gradual decrease of ECT or its long-term continuation might be the best strategy. Notwithstanding, current studies do not address the role of continuation ECT in the truly refractory cases, that is, the clozapine-resistant patients. Our group published a randomized controlled trial of ECT augmentation of clozapine in clozapine-resistant patients with schizophrenia, where the augmentation was vastly superior in efficacy for the acute treatment. The aim of the current study is to evaluate the efficacy of continuation ECT for patients who showed response to the combination of acute ECT and clozapine for treatment-resistant schizophrenia. METHODS: Continuation ECT was offered to all patients who completed the acute study and who met response criterion. We followed a tapered schedule of 4 weekly ECT sessions, followed by 4 ECT sessions every 2 weeks and 2 monthly ECT sessions for a total of 10 sessions. RESULTS: Patients sustained the gains achieved with the acute course of ECT, and no individual patient presented with clinically relevant worsening of symptoms. Moreover, the long-term use of ECT was not associated with added adverse effects. CONCLUSIONS: This is an open pilot study with a small sample size, and results should be interpreted accordingly, but this report offers a relevant starting point for much needed future studies.

Electroconvulsive Therapy Augmentation in Clozapine-Resistant Schizophrenia: A Prospective, Randomized Study.

(Reprinted with permission from Am J Psychiatry 2015; 172:52-58).

A Randomized Comparison of Aripiprazole and Risperidone for the Acute Treatment of First-Episode Schizophrenia and Related Disorders: 3-Month Outcomes.

Research findings are particularly important for medication choice for first-episode patients as individual prior medication response to guide treatment decisions is unavailable. We describe the first large-scale double-masked randomized comparison with first-episode patients of aripiprazole and risperidone, 2 commonly used first-episode treatment agents. One hundred ninety-eight participants aged 15-40 years with schizophrenia, schizophreniform disorder, schizoaffective disorder or psychotic disorder Not Otherwise Specified, and who had been treated in their lifetime with antipsychotics for 2 weeks or less were randomly assigned to double-masked aripiprazole (5-30 mg/d) or risperidone (1-6 mg/d) and followed for 12 weeks. Positive symptom response rates did not differ (62.8% vs 56.8%) nor did time to response. Aripiprazole-treated participants had better negative symptom outcomes but experienced more akathisia. Body mass index change did not differ between treatments but advantages were found for aripiprazole treatment for total and low-density lipoprotein cholesterol, fasting glucose, and prolactin levels. Post hoc analyses suggested advantages for aripiprazole on depressed mood. Overall, if the potential for akathisia is a concern, low-dose risperidone as used in this trial maybe a preferred choice over aripiprazole. Otherwise, aripiprazole would be the preferred choice over risperidone in most situations based upon metabolic outcome advantages and some symptom advantages within the context of similar positive symptom response between medications.

Electroconvulsive therapy augmentation in clozapine-resistant schizophrenia: a prospective, randomized study.

OBJECTIVE: Up to 70% of patients with treatment-resistant schizophrenia do not respond to clozapine. Pharmacological augmentation to clozapine has been studied with unimpressive results. The authors examined the use of ECT as an augmentation to clozapine for treatment-refractory schizophrenia. METHOD: In a randomized single-blind 8-week study, patients with clozapine-resistant schizophrenia were assigned to treatment as usual (clozapine group) or a course of bilateral ECT plus clozapine (ECT plus clozapine group). Nonresponders from the clozapine group received an 8-week open trial of ECT (crossover phase). ECT was performed three times per week for the first 4 weeks and twice weekly for the last 4 weeks. Clozapine dosages remained constant. Response was defined as ≥40% reduction in symptoms based on the psychotic symptom subscale of the Brief Psychiatric Rating Scale, a Clinical Global Impressions (CGI)-severity rating <3, and a CGI-improvement rating ≤2. RESULTS: The intent-to-treat sample included 39 participants (ECT plus clozapine group, N=20; clozapine group, N=19). All 19 patients from the clozapine group received ECT in the crossover phase. Fifty percent of the ECT plus clozapine patients met the response criterion. None of the patients in the clozapine group met the criterion. In the crossover phase, response was 47%. There were no discernible differences between groups on global cognition. Two patients required the postponement of an ECT session because of mild confusion. CONCLUSIONS: The augmentation of clozapine with ECT is a safe and effective treatment option. Further research is required to determine the persistence of the improvement and the potential need for maintenance treatments.

Affective temperaments and neurocognitive functioning in bipolar disorder.

BACKGROUND: There is evidence that patients with bipolar disorder (BD) score higher on affective temperament ratings compared to healthy controls (HCs). Moreover, unaffected relatives demonstrate similar patterns as BD patients suggesting that such temperaments are related to the genetic risk for BD and may serve as endophenotypes for the disorder. It is unknown whether affective temperaments are associated with other core features of BD, such as impairments in neurocognition. This study examined the relationship between affective temperaments and neurocognition in patients with BD and in HCs. METHODS: Temperaments were evaluated using the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego, Auto-questionnaire version (TEMPS-A) in 64 patients with BD and 109 HCs. Neurocognitive functioning was evaluated using the MATRICS Consensus Cognitive Battery (MCCB). Correlational analyses between temperaments and cognition were conducted in BD and HC subjects. RESULTS: Data suggest that affective temperaments and neurocognition are correlated. In BD higher ratings of cyclothymia and irritability were associated with better processing speed, working memory, reasoning and problem-solving. In the HC group, increased irritability was related to worse performance on measures of attention and social cognition. LIMITATIONS: Lack of functional outcome measures to evaluate the impact of temperaments and cognition on psychosocial functioning. It would be useful to test these findings on unaffected relatives of BD patients. CONCLUSIONS: Cyclothymic and irritable temperaments are correlated with specific aspects of neurocognition in BD. This study is among the few exploring the dimensional relationship between temperaments and cognition in BD, and provides preliminary evidence for future studies investigating the neural and genetic mechanisms underlying the association between these variables.

Dopaminergic influences on emotional decision making in euthymic bipolar patients.

We recently reported that the D2/D3 agonist pramipexole may have pro-cognitive effects in euthymic patients with bipolar disorder (BPD); however, the emergence of impulse-control disorders has been documented in Parkinson's disease (PD) after pramipexole treatment. Performance on reward-based tasks is altered in healthy subjects after a single dose of pramipexole, but its potential to induce abnormalities in BPD patients is unknown. We assessed reward-dependent decision making in euthymic BPD patients pre- and post 8 weeks of treatment with pramipexole or placebo by using the Iowa Gambling Task (IGT). The IGT requires subjects to choose among four card decks (two risky and two conservative) and is designed to promote learning to make advantageous (conservative) choices over time. Thirty-four BPD patients completed both assessments (18 placebo and 16 pramipexole). Baseline performance did not differ by treatment group (F=0.63; p=0.64); however, at week 8, BPD patients on pramipexole demonstrated a significantly greater tendency to make increasingly high-risk, high-reward choices across the five blocks, whereas the placebo group's pattern was similar to that reported in healthy individuals (treatment × time × block interaction, p<0.05). Analyses of choice strategy using the expectancy valence model revealed that after 8 weeks on pramipexole, BPD patients attended more readily to feedback related to gains than to losses, which could explain the impaired learning. There were no significant changes in mood symptoms over the 8 weeks, and no increased propensity toward manic-like behaviors were reported. Our results suggest that the enhancement of dopaminergic activity influences risk-associated decision-making performance in euthymic BPD. The clinical implications remain unknown.

Resting-state fMRI connectivity impairment in schizophrenia and bipolar disorder.

BACKGROUND: Schizophrenia and bipolar disorder share aspects of phenomenology and neurobiology and thus may represent a continuum of disease. Few studies have compared connectivity across the brain in these disorders or investigated their functional correlates. METHODS: We used resting-state functional magnetic resonance imaging to evaluate global and regional connectivity in 32 healthy controls, 19 patients with bipolar disorder, and 18 schizophrenia patients. Patients also received comprehensive neuropsychological and clinical assessments. We computed correlation matrices among 266 regions of interest within the brain, with the primary dependent measure being overall global connectivity strength of each region with every other region. RESULTS: Patients with schizophrenia had significantly lower global connectivity compared with healthy controls, whereas patients with bipolar disorder had global connectivity intermediate to and significantly different from those of patients with schizophrenia and healthy controls. Post hoc analyses revealed that compared with healthy controls, both patient groups had significantly lower connectivity in the paracingulate gyrus and right thalamus. Patients with schizophrenia also had significantly lower connectivity in the temporal occipital fusiform cortex, left caudate nucleus, and left thalamus compared with healthy controls. There were no significant differences among the patient groups in any of these regions. Lower global connectivity among all patients was associated with worse neuropsychological and clinical functioning, but these effects were not specific to any patient group. CONCLUSIONS: These findings are consistent with the hypothesis that schizophrenia and bipolar disorder may represent a continuum of global disconnectivity in the brain but that regional functional specificity may not be evident.

Impulsivity in bipolar disorder: relationships with neurocognitive dysfunction and substance use history.

OBJECTIVES: Impulsivity is a core feature in bipolar disorder. Although mood symptoms exacerbate impulsivity, self-reports of impulsivity are elevated, even during euthymia. Neurocognitive processes linked to impulsivity (e.g., attention, inhibition) are also impaired in patients with bipolar disorder, and a high frequency of comorbidities associated with impulsivity, such as substance use disorders, further highlights the clinical relevance of this dimension of the illness. Our objective was to assess the relationship between impulsivity and cognition in bipolar disorder. METHODS: We evaluated impulsivity in 98 patients with bipolar disorder and its relationship with symptoms, cognition, and substance use history. We assessed self-reports of trait impulsivity [Barrett Impulsiveness Scale (BIS)] and impulsive behaviors on the Iowa Gambling Task (IGT). A comprehensive clinical and neurocognitive battery was also completed. Patients were compared with 95 healthy controls. RESULTS: Patients with bipolar disorder had higher scores versus healthy controls on all BIS scales. Performance on the IGT was significantly impaired and patients showed a tendency toward more erratic choices. Depressive symptoms were positively correlated with trait impulsivity and with an increased tendency to attend more readily to losses versus gains on the IGT. We found no significant associations between impulsivity and neurocognition in the full bipolar sample; however, when sub-grouped based on substance abuse history, significant relationships were revealed only in subjects without a substance abuse history. CONCLUSIONS: Our data support prior reports of increased trait impulsivity and impairment on behavioral tasks of impulsiveness in bipolar disorder and suggest a differential relationship between these illness features that is dependent upon history of substance abuse.

Anxiety comorbidity in schizophrenia.

Diagnostic and treatment hierarchical reductionisms have led to an oversight of anxiety syndromes in schizophrenia. Nevertheless, recent data have indicated that anxiety can be a significant source of morbidity in this patient group. This paper reviews current knowledge concerning anxiety comorbidity in schizophrenia, its epidemiology, course, and treatment. A computerized search of the literature published from 1966 to July 2012 was conducted on Medline. Comorbid anxiety disorders are present in 38.3% of subjects with schizophrenia spectrum disorders. The most common anxiety disorder is social phobia followed by post-traumatic stress disorder and obsessive compulsive disorder. The presence and severity of symptoms of anxiety are associated with more severe clinical features and poorer outcomes. Available literature on the treatment consists primarily of case reports and open trials. Fragments of data support the notion of treating these anxiety states and syndromes as co-occurring clinical conditions with adjunctive medications and psychosocial interventions. However, additional work remains to be done on this issue before firm conclusions can be drawn.

The practice of electroconvulsive therapy in Greece.

OBJECTIVE: To describe the practice of electroconvulsive therapy (ECT) in Greece. METHODS: A survey was conducted during the academic year 2008-2009. Electroconvulsive therapy use was investigated for 2007. All civilian institutions providing inpatient care were included. Centers that provided ECT completed a 57-item questionnaire. Centers that did not offer ECT completed a 13-item questionnaire. RESULTS: Fifty-five (82.1%) of 67 institutions responded. Electroconvulsive therapy was offered in 18 hospitals. Only 2 of 10 university hospitals offered ECT. Overall, 137 patients were treated with 1271 sessions in 2007. Only 1.47% discontinued treatment owing to adverse events. There were no deaths. Schizophrenia was the most common diagnosis (41.3%) among those receiving ECT, followed by major depression (28.9%), bipolar depression (9.1%), catatonia (4.1%), suicidal ideation (3.3%), and schizoaffective disorder (2.5%). Physicians considered major depression (93.8%), catatonia (86.5%), schizophrenia (56.3%), and mania (50%) the most appropriate indications. Written informed consent was required in 77.8% of the institutions, whereas the rest required verbal consent. Bilateral ECT was the preferred electrode placement (88.9%). Modified ECT was used exclusively. Propofol was the preferred anesthetic (44.4%), followed by thiopental (38.9%). Seven (38.9%) of 18 hospitals used a fixed stimulus dose at first treatment. Five (27.8%) of 18 hospitals used the half-age method. Continuation/maintenance ECT was used in 33.3% of the hospitals. Outpatient ECT was seldom used. Lack of training, difficult access to anesthesiology, billing issues, and stigma were cited as the main impediments to the practice of ECT. CONCLUSIONS: Electroconvulsive therapy is practiced in moderate numbers in Greece and almost exclusively on an inpatient basis. Lack of training and lack of availability of anesthesiologists were cited as the most common obstacles to providing ECT.

Abnormal temporal lobe white matter as a biomarker for genetic risk of bipolar disorder.

BACKGROUND: Brain white matter (WM) abnormalities have been hypothesized to play an important role in the neurobiology of bipolar disorder (BD). The nature of these abnormalities is not well-characterized, however, and it is unknown whether they occur after disease onset or represent potential markers of genetic risk. METHODS: We examined WM integrity (assessed via fractional anisotropy [FA]) with diffusion tensor imaging in patients with BD (n=26), unaffected siblings of patients with BD (n=15), and healthy volunteers (n=27) to identify WM biomarkers of genetic risk. RESULTS: The FA differed significantly (p<.05; corrected) among the three groups within the right temporal WM. Unaffected siblings had FA values that were intermediate to and significantly different from those of healthy volunteers and patients with BD (healthy control subjects>unaffected siblings>BD). Moreover, FA values in this region correlated negatively and significantly with trait impulsivity in unaffected siblings. Probabilistic tractography indicated that the regional abnormality lies along the inferior fronto-occipital fasciculus, a large intrahemispheric association pathway. CONCLUSIONS: Our results suggest that lower WM integrity in the right temporal lobe might be a biomarker for genetic risk of BD. It is conceivable that the attenuated nature of these WM abnormalities present in unaffected siblings allows for some preservation of adaptive emotional regulation, whereas more pronounced alterations observed in patients is related to the marked emotional dysregulation characteristic of BD.

Cognitive and clinical outcomes associated with cannabis use in patients with bipolar I disorder.

Studies investigating the impact of cannabis use on bipolar clinical characteristics and neurocognition are limited. The objective of the present study was to compare clinical and neurocognitive measures in individuals with bipolar disorder with a history of cannabis use disorder (CUD) versus those without a history of CUD. We conducted a retrospective analysis of a large cohort (N=200) of bipolar I subjects, either with (CUD+; N=50) or without (CUD-; N=150) a history of CUD. We compared the groups on clinical and demographic variables, as well as on performance on neurocognitive tests. Patient groups did not differ regarding age, age of onset or global assessment of functioning. Compared to the CUD- group, the CUD+ group had a higher proportion of men and a higher proportion of patients with a history of psychosis. CUD+ subjects demonstrated significantly better performance on measures of attention, processing speed, and working memory. The history of CUD is associated with history of psychosis, suggestive of poorer clinical prognosis. Interestingly, bipolar patients with history of CUD had better neurocognitive performance as compared to patients with no history of CUD.

Placebo-controlled adjunctive trial of pramipexole in patients with bipolar disorder: targeting cognitive dysfunction.

OBJECTIVE: Patients with bipolar disorder suffer from significant cognitive impairment that contributes directly to functional disability, yet few studies have targeted these symptoms for treatment, and the optimal study design remains unclear. We evaluated the effects of the dopamine D2/D3 receptor agonist pramipexole on cognition in bipolar disorder. METHOD: Fifty stable outpatients with DSM-IV-diagnosed bipolar I or bipolar II disorder enrolled in an 8-week, double-blind, randomized, placebo-controlled cognitive enhancement trial between July 2006 and April 2010. Patients completed neurocognitive testing at baseline and at week 8, and the primary outcome measures were change scores calculated for each of the 11 tasks. Symptoms and side effects were monitored weekly. RESULTS: Forty-five patients completed the study (placebo, n = 24; pramipexole, n = 21), and groups were well matched on demographic and clinical features. Primary cognitive analyses indicated no compelling cognitive benefit of pramipexole versus placebo; however, secondary analyses highlight several important methodological issues for future trials and identify a subgroup of patients who might benefit more readily from cognitive enhancement strategies. This outcome suggests that the study design played a very important role in the results-implying a failed rather than altogether negative trial. Specifically, we found that even very subtle, subsyndromal mood symptoms at baseline had a significant influence on the degree of improvement due to active drug, with strictly euthymic patients faring best (multivariate analysis of variance, P = .03 in euthymic subgroup). In addition, the extent of baseline cognitive impairment also contributed to the likelihood of treatment response. Finally, concomitant medications may weaken, or in some cases enhance, response to cognitive treatment and should be accounted for in study design. CONCLUSIONS: Although our results point toward a lack of clear effect of pramipexole on cognition in bipolar patients, our data revealed a potentially beneficial effect of pramipexole in a subgroup, providing some enthusiasm for pursuing this line of research in the future. Moreover, this study emphasizes the importance of rigorous subject selection for cognitive trials in bipolar illness. Future studies will be necessary to determine the possible clinical and functional implications of these results. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00597896.

Clinical and cognitive correlates of suicide attempts in bipolar disorder: is suicide predictable?

OBJECTIVE: We conducted a retrospective investigation of potential clinical, demographic, and neuropsychological risk factors for suicide attempts in patients diagnosed with bipolar disorder. METHOD: Participants included 67 adult inpatients and outpatients aged 18-60 years meeting DSM-IV criteria for bipolar disorder (bipolar I and II disorders, bipolar disorder not otherwise specified). We assessed demographic factors, mood symptoms, psychosis, trauma history, trait impulsivity, trait aggression, and reasons for living. The primary outcome measures were the Barratt Impulsiveness Scale-version II, Aggression Questionnaire, and 10 cognitive outcome variables. The cognitive outcome variables assessed cognitive performance across several domains, including processing speed, attention, verbal learning, and executive function. Another aspect of cognitive function, decision making, was assessed using the Iowa Gambling Task. The study was conducted from July 2007-July 2009. RESULTS: We found that nonattempters reported significantly higher trait impulsivity scores on the Barratt Impulsiveness Scale compared to attempters (t(57) = 2.2, P = .03) and that, among attempters, lower trait impulsivity score was associated with higher scores of lethality of prior attempts (r(25) = -0.53, P = .01). Analyses revealed no other group differences on demographic, clinical, or neurocognitive variables when comparing attempters versus nonattempters. Regression models failed to identify any significant predictors of past suicide attempt. CONCLUSIONS: The largely negative results of our study are particularly important in highlighting the clinical dilemma faced by many clinicians when trying to predict which patients will make serious suicide attempts and which patients are at a lower risk for acting on suicidal thoughts. A limitation of our work is that we examined stable trait measures of impulsivity among a euthymic sample rather than mood state or the impact of mood state on traits. Overall, we conclude that suicidal behavior is extremely difficult to predict, even when comprehensive clinical and neurocognitive information is available.

The MATRICS consensus cognitive battery in patients with bipolar I disorder.

The Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative was devised to identify a neurocognitive battery to be used in clinical trials targeting cognition in schizophrenia, a process, which resulted in the MATRICS Consensus Cognitive Battery (MCCB). The MCCB has been selected by the United States Food and Drug Administration to be used as the primary outcome measure in registry trials for cognitive agents in schizophrenia. Given the clinical and cognitive overlap between schizophrenia and bipolar disorder (BPD), it is likely that any compound shown to have cognitive benefits in schizophrenia will subsequently be tested in BPD. Unlike the MCCB for schizophrenia, there remains no consensus regarding outcome measures if cognitive trials were to be undertaken in BPD. The utility of the MCCB in BPD has not yet been systematically investigated. We administered the MCCB to 80 bipolar I patients; 37 were strictly euthymic and 43 were symptomatic. We compared their performance with a demographically matched healthy sample (n=148) on seven MCCB domains, and the composite. BPD patients were statistically significantly impaired on five of seven MCCB domains at levels consistent with meta-analytic studies of cognition in BPD. In contrast, patients' performance was less impaired on the Reasoning and Problem-solving and Social Cognition domains, differences that did not survive statistical correction for multiple testing. Symptomatic status only modestly influenced performance. These data suggest that the MCCB, devised for use in schizophrenia, may also represent a useful outcome measure in cognitive trials for BPD. Additional studies should address important psychometric features such as repeatability and potential practice and/or ceiling effects.

Seizure threshold in a large sample: implications for stimulus dosing strategies in bilateral electroconvulsive therapy: a report from CORE.

OBJECTIVE: We sought to examine the relationship of seizure threshold (ST) to age and other demographic characteristics in a large sample where ST was determined by the dose titration (DT) method. We also compared the resulting stimulation levels to estimates predicted by an age-based formula, the half-age (HA) method. METHODS: In a multicenter prospective study, patients received a standardized course of bilateral electroconvulsive therapy for major depression using a brief pulse device. The ST was determined at the first treatment using a fixed algorithm of stimulations. Subsequent seizures were induced at a level 50% higher than the empirically determined ST. We only included data from subjects receiving methohexital anesthesia. We correlated ST with demographic and clinical characteristics of the sample. The actual dosing levels at the second treatment were compared with estimates based on HA. RESULTS: Of the original 531 subjects, 402 met criteria for the current analysis. The ST was positively correlated with age. Male patients had slightly higher ST than female patients. Neither race, severity of illness, psychosis, nor use of psychotropic medications affected ST. Little variability in titrated ST was observed among our patients. An ST of 40 ("percent of charge") or lower was found in 97.5% of patients, with either 20 or 40 in 80% of patients. Ninety-six percent of the patients were treated at the 3 levels of 15%, 30%, or 60%. Estimated HA stimulus levels offered a wider range of choices compared with this particular algorithm used for ST determination at an average level of 18% above the determined ST. CONCLUSIONS: Seizure threshold correlates strongly with age, whereas there is a weaker relation between ST and sex. There was little individual variation of ST determined by the DT method among subjects, possibly because of the wide spacing between steps of this particular titration algorithm. Half-age estimates were 18% above the empirically determined ST. This suggests that the use of the HA estimates at the first treatment may result in fewer stimulations compared with the DT method.