Cerebellar ataxia in youths at risk for bipolar disorder

Cerebellar morphological differences and associations with extrinsic factors in bipolar disorder type I

BACKGROUND

The neural underpinnings of bipolar disorder (BD) remain poorly understood. The cerebellum is ideally positioned to modulate emotional regulation circuitry yet has been understudied in BD. Literature suggests differences in cerebellar activity and metabolism in BD, however findings on structural differences remain contradictory. Potential reasons include combining BD subtypes, small sample sizes, and potential moderators such as genetics, adverse childhood experiences (ACEs), and pharmacotherapy.

METHODS

We collected 3 T MRI scans from participants with (N = 131) and without (N = 81) BD type I, as well as blood and questionnaires. We assessed differences in cerebellar volumes and explored potentially influential factors.

RESULTS

The cerebellar cortex was smaller bilaterally in participants with BD. Polygenic propensity score did not predict any cerebellar volumes, suggesting that non-genetic factors may have greater influence on the cerebellar volume difference we observed in BD. Proportionate cerebellar white matter volumes appeared larger with more ACEs, but this may result from reduced ICV. Time from onset and symptom burden were not associated with cerebellar volumes. Finally, taking sedatives was associated with larger cerebellar white matter and non-significantly larger cortical volume.

LIMITATIONS

This study was cross-sectional, limiting interpretation of possible mechanisms. Most of our participants were White, which could limit the generalizability. Additionally, we did not account for potential polypharmacy interactions.

CONCLUSIONS

These findings suggest that external factors, such as sedatives and childhood experiences, may influence cerebellum structure in BD and may mask underlying differences. Accounting for such variables may be critical for consistent findings in future studies.

Neurological and cerebellar soft signs do not discriminate schizophrenia from bipolar disorder patients

Patients with schizophrenia (SZ) and bipolar disorder (BD) share subtle motor abnormalities called the neurological soft signs (NSS). Since in both diseases there is evidence for alterations in cerebellar functions, structure and connectivity, we expected that the cerebellar soft signs (CSS), analogue of NSS focusing strictly on cerebellar symptoms, would be also a common trait in SZ and BD. We examined 30 patients with BD, 30 patients with SZ and 28 control subjects using the Neurological Evaluation Scale (NES, for NSS) and International Cooperative Ataxia Rating Scale (ICARS, for CSS). SZ and BD did not differ in total and subscales' scores in both NES and ICARS. Subscale analysis revealed that SZ performed significantly worse than controls in all the subscales of both NES and ICARS. BD patients scored significantly worse than controls in all NES subscales and in oculomotor and kinetic subscales of the ICARS, while other ICARS subscales did not differentiate those two groups. To our knowledge this is the first study to show that CSS constitute common symptoms in BD and SZ. We recommend a special focus on those diseases in further research regarding structural and functional changes of cerebellum and their clinical outcome.

Neurological soft signs in non-psychotic patients with cannabis dependence

Psychomotor performance has consistently been found to be altered in chronic cannabis users. Neurological soft signs (NSS) reflect neurological dysfunction involving integrative networks, especially those involving the cerebellum, where cannabinoid receptors are particularly concentrated. Our objective was to study, for the first time, NSS in a group of patients with cannabis dependence compared with a of healthy control subjects, matched for age, gender and level of education. All outpatients seeking treatment for chronic cannabis use in the substance abuse department of Sainte-Anne Hospital in Paris between June 2007 and May 2009 and meeting the cannabis dependence DSM-IV criteria were included in the study (n = 45). Patients with psychotic disorders, bipolar 1 disorder and current alcohol, opioid or cocaine dependence were excluded. All patients and controls were assessed using the Diagnostic Interview for Genetic Studies, which screens for lifetime DSM-IV diagnoses, and the Standardized Neurological Examination of Neurological Soft Signs. NSS scores were significantly higher in patients with cannabis dependence compared with healthy subjects (8.90 ± 4.85 versus 6.71 ± 2.73, respectively, Mann-Whitney: U = 775.0, P = 0.05). Patients had particularly high scores on motor coordination and sensory integration NSS factors. Cannabis dependence is associated with more NSS and especially motor coordination and sensory integration signs. These results suggest that cannabinoids interact with the brain networks underlying NSS, known to be altered in schizophrenia.

Motor function may differentiate attention deficit hyperactivity disorder from early onset bipolar disorder

BACKGROUND

Differentiating between bipolar spectrum disorder (BD) and attention deficit hyperactivity disorder (ADHD) in childhood and adolescence is difficult because the clinical presentation is influenced by ongoing neural development, causing considerable symptom overlap. Motor problems and neurological soft signs have been associated with ADHD for decades. Little is known about motor skills in BD. Here we assess the diagnostic accuracy of neuromotor deviations in differentiating ADHD from BD in clinical practice. We also investigate if these deviations exist in concurrent ADHD and BD, thus indicating true comorbidity

METHODS

64 patients 6-18 years (31 girls, 33 boys) fulfilling the diagnostic criteria of BD, ADHD combined subtype (ADHD-C) or comorbid BD and ADHD-C, were compared using an age-standardized neuromotor test; NUBU. Categorical variables were analyzed using cross table with two-tailed chi square test or Fisher's exact test when appropriate. Continuous variables were analyzed by Kruskal-Wallis test and, if significant, Mann-Whitney U test and ROC plots.

RESULTS

The ADHD-C group and the comorbid ADHD-C and BD group both showed significantly more neurological soft signs (p less than 0.01) and lower mean static coordination percentile (p less than 0.01) than the BD group. The positive predictive value of NUBU in the diagnosis of ADHD-C with or without concurrent BD was 89% (80-95) for total soft signs and 87% (79-95) for static coordination below the 7.5 percentile.

CONCLUSION

An age-standardized neuromotor test battery may promote diagnostic accuracy in differentiating ADHD from BD in clinical practice, and help evaluating whether symptoms of ADHD in children who have BD reflect symptom overlap or real comorbidity. This may have important implications for everyday diagnostic work.