Factor analysis of repetitive behaviors in Autism as measured by the Y-BOCS.

The authors carried out a factor analysis of the Yale-Brown Obsessive-Compulsive Scale checklist at the category level in order to reduce the number of variables in this domain and ultimately identify possible endophenotypes; 181 children with autism were enrolled. The authors estimated a tetrachoric correlation matrix among the dichotomous symptom categories and then used exploratory and confirmatory factor analyses to identify a clinically meaningful factor structure for this correlation matrix. Their analysis supported a four-factor solution: obsessions, higher-order repetitive behaviors, lower-order repetitive behaviors, and hoarding. These findings are another step in the effort to identify genetically and biologically distinct groups within this population.

Relationship between whole blood serotonin and repetitive behaviors in autism.

This study was conducted to examine the relationship between whole blood serotonin level and behavioral symptoms in 78 subjects with autism. No significant associations were found between serotonin level and the primary behavioral outcome measures. However, a significant inverse relationship between serotonin level and self-injury was demonstrated.

Levetiracetam versus placebo in childhood and adolescent autism: a double-blind placebo-controlled study.

The purpose of this study was to determine the safety and efficacy of the anticonvulsant levetiracetam in the treatment of children with autism. A previous open-label study in autistic children treated with levetiracetam demonstrated effectiveness in hyperactivity, impulsivity/aggression, and mood lability. Twenty patients with autism ranging from 5 to 17 years of age were entered into a 10-week, placebo-controlled, double-blind trial of levetiracetam versus placebo. The mean maximum dosage for levetiracetam was 862.50+/-279.19 mg/day. We evaluated global improvement of autism with the Clinical Global Impression-Improvement (CGI-I) Scale and aggression and affective instability with the Aberrant Behavior Checklist (ABC) parent and teacher ratings. We measured repetitive behaviors using the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS) score and impulsivity and hyperactivity with the Conners' Rating Scale-Revised: Long Version for parent and teacher. No significant difference was found between levetiracetam and placebo groups comparing the change in CGI-I (t=0.350, d.f.=13.621, P=0.765), nor on change in ABC, CY-BOCS or Conners' scales. These findings suggest that levetiracetam does not improve behavioral disturbances of autism, but are limited by the small sample size and lack of stratification of the autistic sample at baseline.

Rest tremor in patients with essential tremor: prevalence, clinical correlates, and electrophysiologic characteristics.

BACKGROUND: Isolated rest tremor, which is observed in some patients with essential tremor (ET), poses a diagnostic challenge. The phenomenon has been examined in few studies and is poorly understood. OBJECTIVES: To determine the prevalence and study the clinical correlates of rest tremor in ET and to examine the electrophysiologic features in a subgroup of patients. METHODS: Sixty-four patients with ET cared for at a tertiary referral center underwent neurologic examination. Five of 12 patients with rest tremor also underwent quantitative computerized tremor analysis using accelerometry and handwritten spiral analysis. RESULTS: Twelve of 64 patients with ET had rest tremor (prevalence, 18.8%; 95% confidence interval, 9.2%-28.4%). Compared with the 52 patients with ET without rest tremor, these 12 had disease of longer duration and greater severity. Also, their ET was more widely disseminated, as evidenced by a larger proportion with head tremor. None had clinical signs of bradykinesia or rigidity. The 5 patients with rest tremor who underwent electrophysiologic study had electrophysiologic features consistent with parkinsonism (eg, slow spiral speed and increased decrement of spiral speed with radius). CONCLUSIONS: In our sample, 1 in 5 patients with ET had rest tremor. The tremor was associated with disease that was more severe, more disseminated, and of longer duration. Some of these patients had electrophysiologic features consistent with parkinsonism. The basis for the rest tremor could be basal ganglia involvement, raising the possibility that the pathologic process responsible for ET may extend to these structures.

Body mass index in essential tremor.

BACKGROUND: The pathogenesis of essential tremor (ET) is unknown, but it could be neurodegenerative. Weight loss has been observed in patients with neurodegenerative diseases. OBJECTIVES: To compare body mass index (BMI) (calculated as weight in kilograms divided by the square of height in meters) in ET cases and controls and to determine whether BMI is correlated with tremor severity and duration. METHODS: Patients with ET were ascertained from the Neurological Institute of New York, New York, NY. Control subjects were recruited from 2 studies at the same institution. Height and weight were measured and BMI was calculated. Dietary data were collected using a Willett Semi-Quantitative Food-Frequency Questionnaire. Tremor severity was assessed using a clinical scale and the Klove Matthews Motor Steadiness Battery. RESULTS: The 78 cases and 242 controls were of similar age. Mean (SD) BMI in cases vs controls was 26.5 (5.0) vs 28.2 (4.8) (P =.008). This difference remained significant in an unconditional linear regression analysis that adjusted for age, sex, ethnicity, and years of education (P =.02). Mean daily caloric intake was similar in cases and controls. In cases, BMI was negatively correlated with both measures of tremor severity (r = -0.22; P =.05 and r = -0.24; P =.03) and with tremor duration (r = -0.22; P =.05). CONCLUSIONS: The BMI was lower in ET cases than in controls, and lower BMI was associated with disease of greater severity and longer duration. Caloric intake did not differ between groups, suggesting that lower BMI is not due to a reduction in calories. Lower BMI may be due to increased energy expenditure in ET.

Olfactory dysfunction in essential tremor: a deficit unrelated to disease duration or severity.

Because olfactory dysfunction is a feature of neurodegenerative diseases, the authors hypothesized that it would be present in essential tremor. Thirty-seven cases and control subjects underwent the University of Pennsylvania Smell Identification Test. Mean score was lower in cases than in control subjects (29.0 +/- 6.1 vs 31.9 +/- 4.6, p = 0.02) and was not correlated with tremor severity or duration.

Metabolic abnormality in the cerebellum in patients with essential tremor: a proton magnetic resonance spectroscopic imaging study.

The pathological basis for essential tremor (ET) is unknown. We used proton magnetic resonance spectroscopic imaging (1H MRSI) in 16 ET patients and 11 controls to measure levels of intracellular metabolites, including N-acetyl-L-aspartate (NAA) and total choline, relative to total creatine (tCR), in several brain regions (cerebellum, thalamus, basal ganglia). Multislice 1H MRSI data were acquired on a 1.5 T GE Signa Scanner by prescribing four 15-mm axial-oblique slices. The mean (standard deviation) cerebellar cortical NAA/tCR was reduced in cases compared to controls (1.53 [0.36] versus 1.91 [0.49], P = 0.03). There was an inverse association between cerebellar cortical NAA/tCR and dominant arm tremor severity (r = -0.59, P = 0.02). The reduction in cerebellar cortical NAA/tCR indicates that there is neuronal damage or loss in ET, suggesting that ET may be a neurodegenerative disease.

Community-based data on associations of disease duration and age with severity of essential tremor: implications for disease pathophysiology.

The pathophysiology of essential tremor (ET) is not well understood, although the tremor often worsens over time. Several processes could contribute, including the inherent worsening of the underlying disease with increasing disease duration and the effects of aging on the nervous system. Our objective was to examine the associations of disease duration and age with tremor severity in ET. Cases were ascertained from a community-based study of ET in northern Manhattan, New York. A neurologist rated tremor severity using a clinical rating scale and assigned a total tremor score (0-36 [maximum]). Analyses were repeated in a sample of cases from a tertiary referral center, the Neurological Institute of New York. There were 55 cases from the community-based study (mean age, 72.1 years, mean disease duration, 13.2 years). Disease duration was associated with the total tremor score (r = 0.30; P = 0.02). Age was associated with the total tremor score (r = 0.30; P = 0.025). In a linear regression analysis the dependent variable was the total tremor score and independent variables were disease duration, age gender. Duration (beta = 0.11; P = 0.02) and age (beta = 0.10; P = 0.02) were independently associated with the total tremor score. Results were similar in 79 ET cases from the Neurological Institute. Disease duration and age were independently associated with tremor severity in ET. This suggests that the reported increase in tremor severity may be related to the inherent worsening of the disease with increasing duration that this is independent of age and age-related processes like neuronal attrition and change in tremor frequency.

Survey of essential tremor patients on their knowledge about the genetics of the disease.

A group of essential tremor (ET) patients were surveyed on their knowledge of the genetics of ET in order to provide important information to clinicians who care for and educate patients about this disease. ET patients were ascertained from neurologists at Columbia-Presbyterian Medical Center. A 5- to 10-minute survey was administered to assess knowledge of the genetics of ET. Fifty ET patients had been living with their disease for a mean of 24.2 years. Approximately half (n = 27) reported a family history of ET. When asked, "What causes ET," 12 (24%) replied that it was "hereditary." Even among the 27 who reported a family history, only 25.9% replied that it was "hereditary." A minority of patients (12 [24%]) thought that it was "very likely" that other members of their family would develop the disease some day. Three patients were aware that genetic linkage had been established. Our findings suggest that the majority of patients with ET are not well informed about the genetic basis for the disease. Because of recent advances in genetic research, physicians may need to incorporate more genetic information and education into their practice, including information on risk to other family members and genetic testing. It is hoped that these survey results could be used to improve patient education and to provide clinicians with further insight into patients' perspectives.