Trait Impulsivity Is Independent of Mild Cognitive Impairment in a Parkinson's Disease Cohort

Quality of life implications for elevated trait impulsivity in people with Parkinson's disease

BACKGROUND

Several non-motor features of Parkinson's disease (PD) are known to adversely affect patient health-related quality of life (HRQL). However, the specific impact of neuropsychiatric complications, such as impulsive behaviour, is yet to be elucidated.

OBJECTIVES

The present cross-sectional, observational study aimed to investigate the effects of heightened trait impulsivity on HRQL in individuals with PD.

METHODS

A total of 322 people with idiopathic PD were sequentially recruited from Movement Disorder clinics across Australia. Trait impulsivity in patients was determined by Barratt's Impulsiveness Scale Version 11 (BIS-11), and grouped into tertiles (low, medium, and high). Patient HRQL was determined by the 39-item Parkinson's Disease Questionnaire (PDQ-39), complemented by the Cambridge Behavioural Inventory-Revised (CBI-R) indicating caregivers' perception of patient HRQL.

RESULTS

When total BIS-11 scores were grouped into tertiles, patient perceived and caregiver-perceived HRQL were 1.7-fold (p < .001) and 2.2-fold (p < .001) worse in the high BIS-11 group when compared to patients in the low group. Univariate analysis revealed significant associations between second-order attentional (p < .001) and non-planning (p < .001) impulsivity domains with PDQ-39 scores. When controlling for confounding demographic and clinical variables, a multivariate linear regression model revealed second-order attentional impulsivity was independently predictive of poor patient perceived HRQL (p < .001).

CONCLUSION

These findings suggest that increasing trait impulsivity is significantly associated with patient perceived HRQL in PD. Improved knowledge and recognition of subclinical impulsivity may guide clinicians' treatment and reduce disease burden for patients experiencing PD symptoms.

Trait impulsivity in Juvenile Myoclonic Epilepsy

Objective

Impulsivity is a multidimensional construct that can predispose to psychopathology. Meta‐analysis demonstrates an association between response impulsivity and Juvenile Myoclonic Epilepsy (JME), a common genetic generalized epilepsy. Here, we test the hypotheses that trait impulsivity is (i) elevated in JME compared to controls; (ii) moderated by specific seizure characteristics; and (iii) associated with psychiatric adverse effects of antiepileptic drugs (AEDs).

Methods

322 participants with JME and 126 age and gender‐matched controls completed the Barratt’s Impulsiveness Scale (BIS‐brief) alongside information on seizure history and AED use. We compared group BIS‐brief scores and assessed associations of JME BIS‐brief scores with seizure characteristics and AED adverse effects.

Results

The mean BIS‐brief score in JME was 18.1 ± 4.4 compared with 16.2 ± 4.1 in controls (P = 0.0007). Elevated impulsivity was associated with male gender (P = 0.027), frequent absence seizures (P = 0.0004) and lack of morning predominance of myoclonus (P = 0.008). High impulsivity significantly increased the odds of a psychiatric adverse event on levetiracetam (P = 0.036), but not any other psychiatric or somatic adverse effects.

Interpretation

Trait impulsivity is elevated in JME and comparable to scores in personality and neurotic disorders. Increased seizure frequency and absence of circadian seizure pattern moderate BIS score, suggesting disruption of both cortico‐striatal and thalamocortical networks as a shared mechanism between seizures and impulsivity in JME. These findings warrant consideration of impulsivity as a distinct target of intervention, and as a stratifying factor for AED treatment in JME, and perhaps other types of epilepsy. The role of impulsivity in treatment adherence and psychosocial outcome requires further investigation.

Elevated Serum Ceruloplasmin Levels Are Associated with Higher Impulsivity in People with Parkinson's Disease

BACKGROUND

Heightened impulsivity has been reported in a subset of people with Parkinson's disease (PwP) and is considered a risk factor for the development of impulse control disorders (ICDs). However, at present, there are no recognised biochemical markers of heightened impulsivity.

OBJECTIVES

To determine if ceruloplasmin, a serum marker involved in the regulation of iron and copper homeostasis, is associated with trait impulsivity in PwP.

METHODS

The study measured serum ceruloplasmin and impulsivity using the Barratt Impulsiveness Scale (BIS-11) in an Australian cohort of 214 PwP. Multivariate general linear models (GLMs) were used to identify whether higher serum ceruloplasmin levels (>75th percentile) were significantly predictive of BIS-11 scores.

RESULTS

Serum ceruloplasmin was higher in females with PD (p < 0.001) and associated with MDS-UPDRS III, Hoehn and Yahr, and ACE-R scores (p < 0.05). When correcting for covariates, higher serum ceruloplasmin concentrations were associated with the 2nd order nonplanning impulsivity and with the 1st order self-control and cognitive complexity impulsivity domains.

CONCLUSIONS

Higher serum ceruloplasmin levels are independently associated with heightened nonplanning impulsivity in PwP. Thus, serum ceruloplasmin levels may have clinical utility as a marker for heightened impulsivity in PD.

Increased large-scale inter-network connectivity in relation to impulsivity in Parkinson's disease

Impulsivity is a neuropsychiatric feature of Parkinson’s disease (PD). We investigated the pathophysiology of impulsivity in PD using resting-state functional magnetic resonance imaging (rs-fMRI). We investigated 45 patients with idiopathic PD and 21 healthy controls. Based on Barratt Impulsiveness Scale (BIS-11) score, PD patients were classified as higher (PD-HI) or lower impulsivity (PD-LI). Functional connectivity (FC) between various large-scale brain networks were analysed using the CONN toolbox. FC between the right frontoparietal network (FPN) and medial visual network (MVN) was significantly higher in PD-HI patients than PD-LI patients (false discovery rate [FDR]-adjusted p = 0.0315). FC between the right FPN and MVN had a significant positive correlation with total BIS-11 score (FDR-adjusted p = 0.010) and the attentional impulsivity (FDR-adjusted p = 0.046) and non-planning impulsivity subscale scores (FDR-adjusted p = 0.018). On the other hand, motor impulsivity subscale score had a significant negative correlation with the FC between the default-mode and salience networks (right supramarginal gyrus, FDR-adjusted p = 0.018; anterior cingulate cortex, FDR-adjusted p = 0.027); this trend was observed in healthy controls. The attentional and non-planning impulsivity, regarded as ‘cognitive’ impulsivity, may be associated with dysfunction in integration of perceptual information and flexible cognitive control in PD.