Purpose Gamma‐aminobutyric acid (GABA) abnormalities have been implicated in a range of neuropsychiatric disorders. Despite substantial interest in probing GABA in vivo, human imaging studies relying on magnetic resonance spectroscopy (MRS) have generally been hindered by technical challenges, including GABA’s relatively low concentration and spectral overlap with other metabolites. Although past studies have shown moderate‐to‐strong test‐retest repeatability and reliability of GABA within certain brain regions, many of these studies have been limited by small sample sizes. Methods GABA+ (macromolecular‐contaminated) test‐retest reliability and repeatability were assessed via a Meshcher‐Garwood point resolved spectroscopy (MEGA‐PRESS) MRS sequence in the rostral anterior cingulate cortex (rACC; n = 21) and dorsolateral prefrontal cortex (dlPFC; n = 20) in healthy young adults. Data were collected on a 3T scanner (Siemens Prisma, Siemens Healthcare, Erlangen, Germany) and GABA+ results were reported in reference to both total creatine (GABA+/tCr) and water (GABA+/water). Results Results showed strong test‐retest repeatability (mean GABA+/tCr coefficient of variation [CV] = 4.6%; mean GABA+/water CV = 4.0%) and reliability (GABA+/tCr intraclass correlation coefficient [ICC] = 0.77; GABA+/water ICC = 0.87) in the dlPFC. The rACC showed acceptable (but comparatively lower) repeatability (mean GABA+/tCr CV = 8.0%; mean GABA+/water CV = 7.5%), yet low‐moderate reliability (GABA+/tCr ICC = 0.40; GABA+/water ICC = 0.44). Conclusion The present study found excellent GABA+ MRS repeatability and reliability in the dlPFC. The rACC showed inferior results, possibly because of a combination of shimming impedance and measurement error. These data suggest that MEGA‐PRESS can be utilized to reliably distinguish participants based on dlPFC GABA+ levels, whereas the mixed results in the rACC merit further investigation.

Despite limitations, the study supports that there are symptoms in the JHD population that are not considered classic, however, are common and significant for patients and caregivers.

No abstract

In this direct replication of Mueller and Oppenheimer’s (2014) Study 1, participants watched a lecture while taking notes with a laptop ( n = 74) or longhand ( n = 68). After a brief distraction and without the opportunity to study, they took a quiz. As in the original study, laptop participants took notes containing more words spoken verbatim by the lecturer and more words overall than did longhand participants. However, laptop participants did not perform better than longhand participants on the quiz. Exploratory meta-analyses of eight similar studies echoed this pattern. In addition, in both the original study and our replication, higher word count was associated with better quiz performance, and higher verbatim overlap was associated with worse quiz performance, but the latter finding was not robust in our replication. Overall, results do not support the idea that longhand note taking improves immediate learning via better encoding of information.

There is a known negative association between cytosine–adenine–guanine (CAG) repeat length and the age of motor onset (AMO) in adult-onset Huntington’s Disease (AOHD). This relationship is less clear in patients with juvenile-onset Huntington’s disease (JOHD), however, given the rarity of this patient population. The aim of this study was to investigate this relationship amongst a relatively large group of patients with JOHD using data from the Kids-JOHD study. Additionally, we analyzed data from the Enroll-HD platform and the Predict-HD study to compare the relationship between CAG repeat length and AMO amongst patients with AOHD to that amongst patients with JOHD using linear regression models. In line with previous reports, the variance in AMO that was predicted by CAG repeat length was 59% (p < 0.0001) in the Predict-HD study and 57% from the Enroll-HD platform (p < 0.0001). However, CAG repeat length predicted 84% of the variance in AMO amongst participants from the Kids-JOHD study (p < 0.0001). These results indicate that there may be a stronger relationship between CAG repeat length and AMO in patients with JOHD as compared to patients with AOHD. These results provide additional information that may help to model disease progression of JOHD, which is beneficial for the planning and implementation of future clinical trials.

Background: Correlates of cannabis use and dependence among young adults have been widely studied. However, it is not known which factors are most strongly associated with severity of cannabis use dependence (CUD) severity. Identification of the salient correlates of CUD severity will be of increasing clinical significance as use becomes more socially normative.Methods: This study used a data-driven, hypothesis-free approach to examine the most robust correlates of CUD severity among a sample of 76 young adults (ages 18 to 25 years) who used cannabis at least weekly. Seventy-one candidate variables were examined for association with CUD severity. These included demographic variables, self-reported and psychodiagnostic assessments of mood and anxiety, self-reported measures of personality, cannabis and other substance use characteristics, and objective and subjective measures of cognition.Results: Of the 71 candidate variables considered, 27 were associated with CUD severity on a univariate level at a p-value ≤ 0.20. Correlates of CUD severity in the multivariable model using stepwise selection were: more frequent cannabis use in the past 90 days, greater expectancies that cannabis causes cognitive and behavioral impairment, greater self-reported metacognitive deficits, greater anxiety, and lower reaction time variability on a test of sustained attention. Internal validation tests support high prediction accuracy of all variables in the multivariable model, except for lower reaction time variability.Conclusions: Cannabis use frequency, beliefs about use, perceived cognitive abilities, and anxiety are robustly associated with CUD severity in young adult, regular cannabis users, and may be important in guiding prevention and treatment efforts.

No abstract

No abstract