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result(s) for
"Griffiths, Kristi R"
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A Systematic Review of Imaging Studies in the Combined and Inattentive Subtypes of Attention Deficit Hyperactivity Disorder
by
Korgaonkar, Mayuresh S.
,
Griffiths, Kristi R.
,
Saad, Jacqueline Fifi
in
Attention deficit hyperactivity disorder
,
attention deficit hyperactivity disorder (ADHD)
,
Brain architecture
2020
Objective: Insights to underlying neural mechanisms in ADHD have emerged from neuroimaging research; however, the neural mechanisms that distinguish ADHD subtypes remain inconclusive. Method: We reviewed nineteen studies integrating magnetic resonance imaging (structural, diffusion, fMRI) findings into a framework exploring pathophysiological mechanisms underlying the combined (ADHD-C) and predominantly inattentive (ADHD-I) ADHD subtypes. Results: Despite equivocal structural MRI results, findings from fMRI and DTI imaging modalities consistently implicate disrupted connectivity in regions and tracts involving frontal striatal thalamic in ADHD-C and frontoparietal neural networks in ADHD-I. Alterations of the default mode, cerebellum and motor networks in ADHD-C and cingulo-frontoparietal attention and visual networks in ADHD-I highlight network organization differences between subtypes. Conclusion: Growing evidence from neuroimaging studies highlight neurobiological differences between ADHD clinical subtypes, particularly from a network perspective. Understanding brain network organization and connectivity may help us to better conceptualize the ADHD types and their symptom variability.
Journal Article
Default-mode and fronto-parietal network connectivity during rest distinguishes asymptomatic patients with bipolar disorder and major depressive disorder
by
Rai Sabina
,
Griffiths, Kristi R
,
Breukelaar, Isabella A
in
Bipolar disorder
,
Mental depression
2021
Bipolar disorder (BD) is commonly misdiagnosed as major depressive disorder (MDD). This is understandable, as depression often precedes mania and is otherwise indistinguishable in both. It is therefore imperative to identify neural mechanisms that can differentiate the two disorders. Interrogating resting brain neural activity may reveal core distinguishing abnormalities. We adopted an a priori approach, examining three key networks documented in previous mood disorder literature subserving executive function, salience and rumination that may differentiate euthymic BD and MDD patients. Thirty-eight patients with BD, 39 patients with MDD matched for depression severity, and 39 age-gender matched healthy controls, completed resting-state fMRI scans. Seed-based and data-driven Independent Component analyses (ICA) were implemented to examine group differences in resting-state connectivity (pFDR < 0.05). Seed analysis masks were target regions identified from the fronto-parietal (FPN), salience (SN) and default-mode (DMN) networks. Seed-based analyses identified significantly greater connectivity between the subgenual cingulate cortex (DMN) and right dorsolateral prefrontal cortex (FPN) in BD relative to MDD and controls. The ICA analyses also found greater connectivity between the DMN and inferior frontal gyrus, an FPN region in BD relative to MDD. There were also significant group differences across the three networks in both clinical groups relative to controls. Altered DMN–FPN functional connectivity is thought to underlie deficits in the processing, management and regulation of affective stimuli. Our results suggest that connectivity between these networks could potentially distinguish the two disorders and could be a possible trait mechanism in BD persisting even in the absence of symptoms.
Journal Article
Patient Perceptions of Ozempic (Semaglutide) for Weight Loss: Mixed Methods Analysis of Online Medication Reviews
2026
Ozempic (semaglutide) has received widespread attention for its appetite-suppressing effects, leading to extensive off-label use for weight loss. Although gastrointestinal side effects are well documented, less is known about how users assess the trade-off between perceived benefits and adverse effects, or how these assessments influence treatment discontinuation. Importantly, existing insights are often limited to clinical trial populations and may not fully reflect real-world experiences.
This study applies a novel infoveillance approach to examine patient-reported experiences with off-label Ozempic use for weight loss and to identify the factors most strongly associated with user satisfaction and treatment discontinuation.
We analyzed 60 publicly available, self-selected, anonymous user reviews of Ozempic from Drugs.com. Reviews were initially examined using thematic analysis to identify key themes describing patients' lived experiences with treatment. These qualitative themes were then linked to user-provided ratings of perceived drug efficacy (1-10 scale) and statements regarding intent to continue or discontinue treatment. This mixed methods approach enabled the integration of qualitative depth with quantitative patterns within naturally occurring, deidentified online data.
Three major themes emerged from the thematic analysis: (1) change in body weight and appetite, (2) nonweight-related symptoms and side effects, and (3) plans for ongoing use versus discontinuation. Two-thirds of respondents reported reduced appetite, food cravings, or body weight. Gastrointestinal complaints were common (reported by 37 of 60, 62%, reviewers) but did not significantly (P=.39) influence satisfaction ratings or decisions to continue treatment. Instead, minimal/no weight loss and the emergence of nongastrointestinal side effects were more frequently associated with low overall satisfaction and discontinuation. Effective weight loss, even when accompanied by gastrointestinal side effects, was associated with a greater willingness to continue Ozempic treatment.
This study presents a novel application of infoveillance methods to characterize real-world patient attitudes toward off-label Ozempic use. Satisfaction was driven primarily by perceived effectiveness rather than tolerability. Key limitations are the self-selected nature of the sample, reliance on anonymous, self-reported data, and the lack of demographic, dosing, or treatment-duration information. Nonetheless, these findings underscore the value of online health forums as a rich and underutilized source of patient-centered insights to inform obesity treatment strategies, adherence interventions, and public health communication.
Journal Article
Structural brain network topology underpinning ADHD and response to methylphenidate treatment
by
Griffiths, Kristi R
,
Braund, Taylor A
,
Williams, Leanne M
in
Attention deficit hyperactivity disorder
,
Efficiency
2021
Behavioural disturbances in attention deficit hyperactivity disorder (ADHD) are thought to be due to dysfunction of spatially distributed, interconnected neural systems. While there is a fast-growing literature on functional dysconnectivity in ADHD, far less is known about the structural architecture underpinning these disturbances and how it may contribute to ADHD symptomology and treatment prognosis. We applied graph theoretical analyses on diffusion MRI tractography data to produce quantitative measures of global network organisation and local efficiency of network nodes. Support vector machines (SVMs) were used for comparison of multivariate graph measures of 37 children and adolescents with ADHD relative to 26 age and gender matched typically developing children (TDC). We also explored associations between graph measures and functionally-relevant outcomes such as symptom severity and prediction of methylphenidate (MPH) treatment response. We found that multivariate patterns of reduced local efficiency, predominantly in subcortical regions (SC), were able to distinguish between ADHD and TDC groups with 76% accuracy. For treatment prognosis, higher global efficiency, higher local efficiency of the right supramarginal gyrus and multivariate patterns of increased local efficiency across multiple networks at baseline also predicted greater symptom reduction after 6 weeks of MPH treatment. Our findings demonstrate that graph measures of structural topology provide valuable diagnostic and prognostic markers of ADHD, which may aid in mechanistic understanding of this complex disorder.
Journal Article
No support for white matter connectivity differences in the combined and inattentive ADHD presentations
by
Williams, Leanne M.
,
Korgaonkar, Mayuresh S.
,
Kohn, Michael R.
in
Adolescent
,
Adolescents
,
Anisotropy
2021
Evidence from functional neuroimaging studies support neural differences between the Attention Deficit Hyperactivity Disorder (ADHD) presentation types. It remains unclear if these neural deficits also manifest at the structural level. We have previously shown that the ADHD combined, and ADHD inattentive types demonstrate differences in graph properties of structural covariance suggesting an underlying difference in neuroanatomical organization. The goal of this study was to examine and validate white matter brain organization between the two subtypes using both scalar and connectivity measures of brain white matter. We used both tract-based spatial statistical (TBSS) and tractography analyses with network-based Statistics (NBS) and graph-theoretical analyses in a cohort of 35 ADHD participants (aged 8–17 years) defined using DSM-IV criteria as combined (ADHD-C) type (n = 19) or as predominantly inattentive (ADHD-I) type (n = 16), and 28 matched neurotypical controls. We performed TBSS analyses on scalar measures of fractional anisotropy (FA), mean (MD), radial (RD), and axial (AD) diffusivity to assess differences in WM between ADHD types and controls. NBS and graph theoretical analysis of whole brain inter-regional tractography examined connectomic differences and brain network organization, respectively. None of the scalar measures significantly differed between ADHD types or relative to controls. Similarly, there were no tractography connectivity differences between the two subtypes and relative to controls using NBS. Global and regional graph measures were also similar between the groups. A single significant finding was observed for nodal degree between the ADHD-C and controls, in the right insula (corrected p = .029). Our result of no white matter differences between the subtypes is consistent with most previous findings. These findings together might suggest that the white matter structural architecture is largely similar between the DSM-based ADHD presentations is similar to the extent of being undetectable with the current cohort size.
Journal Article
Action-value comparisons in the dorsolateral prefrontal cortex control choice between goal-directed actions
by
Morris, Richard W.
,
Balleine, Bernard W.
,
Griffiths, Kristi R.
in
59/36
,
631/378/116
,
631/378/1457/1945
2014
It is generally assumed that choice between different actions reflects the difference between their action values yet little direct evidence confirming this assumption has been reported. Here we assess whether the brain calculates the absolute difference between action values or their relative advantage, that is, the probability that one action is better than the other alternatives. We use a two-armed bandit task during functional magnetic resonance imaging and modelled responses to determine both the size of the difference between action values (
D
) and the probability that one action value is better (
P
). The results show haemodynamic signals corresponding to
P
in right dorsolateral prefrontal cortex (dlPFC) together with evidence that these signals modulate motor cortex activity in an action-specific manner. We find no significant activity related to
D
. These findings demonstrate that a distinct neuronal population mediates action-value comparisons, and reveals how these comparisons are implemented to mediate value-based decision-making.
In humans, choice between actions depends on the ability to compare action–outcome values. Here, the authors show that action–outcome values are compared on the basis of the relative advantage of a particular action over alternative actions, which takes place in the right dorsolateral prefrontal cortex of the brain.
Journal Article
Intrinsic Functional Connectivity in the Default Mode Network Differentiates the Combined and Inattentive Attention Deficit Hyperactivity Disorder Types
by
Griffiths, Kristi R
,
Braund, Taylor A
,
Saad, Jacqueline F
in
Attention deficit hyperactivity disorder
,
Brain mapping
,
Brain research
2022
Neuroimaging studies have revealed neurobiological differences in ADHD, particularly studies examining connectivity disruption and anatomical network organization. However, the underlying pathophysiology of ADHD types remains elusive as it is unclear whether dysfunctional network connections characterize the underlying clinical symptoms distinguishing ADHD types. Here, we investigated intrinsic functional network connectivity to identify neural signatures that differentiate the combined (ADHD-C) and inattentive (ADHD-I) presentation types. Applying network-based statistical (NBS) and graph theoretical analysis to task-derived intrinsic connectivity data from completed fMRI scans, we evaluated default mode network (DMN) and whole-brain functional network topology in a cohort of 34 ADHD participants (aged 8–17 years) defined using DSM-IV criteria as predominantly inattentive (ADHD-I) type (n = 15) or combined (ADHD-C) type (n = 19), and 39 age and gender-matched typically developing controls. ADHD-C were characterized from ADHD-I by reduced network connectivity differences within the DMN. Additionally, reduced connectivity within the DMN was negatively associated with ADHD-RS hyperactivity-impulsivity subscale score. Compared with controls, ADHD-C but not ADHD-I differed by reduced connectivity within the DMN; inter-network connectivity between the DMN and somatomotor networks; the DMN and limbic networks; and between the somatomotor and cingulo-frontoparietal, with ventral attention and dorsal attention networks. However, graph-theoretical measures did not significantly differ between groups. These findings provide insight into the intrinsic networks underlying phenotypic differences between ADHD types. Furthermore, these intrinsic functional connectomic signatures support neurobiological differences underlying clinical variations in ADHD presentations, specifically reduced within and between functional connectivity of the DMN in the ADHD-C type.
Journal Article
Exploring bi-directional impacts of Lisdexamfetamine dimesylate on psychological comorbidities and quality of life in people with Binge Eating Disorder
2024
Background
Lisdexamfetamine dimesylate (LDX) has demonstrated safety and efficacy for treatment of Binge Eating Disorder (BED). However, to date, trials have not included participants with co-occurring psychiatric disorders. This study explores how LDX affects eating disorder psychopathology, symptoms of common psychiatric comorbidities of BED (ADHD, depression, anxiety), and psychological quality of life, in people with moderate to severe BED.
Methods
These are secondary analyses of an open-label LDX trial conducted in 41 adults (18–40 years) over eight-weeks. Participants received LDX titrated to 50 or 70 mg. Clinical assessments and self-report questionnaires were conducted at baseline and 8-week follow-up.
Results
Eating disorder psychopathology and psychological quality of life improved after 8-weeks of LDX. No significant group-level changes in depression, anxiety or ADHD severity scores were observed. However, the majority within the small subsets with elevated depression and ADHD symptoms experienced reduced depressive and inattentive symptom severity, respectively.
Conclusions
We provide proof-of-concept evidence that LDX may provide broader psychological benefits to individuals with BED, beyond reducing their BE frequency. Effects of LDX on anxiety should be monitored closely by clinicians. Early indications suggest that LDX may be effectively used in people with BED, with and without co-occurring psychiatric conditions, however tolerability may be lower in highly complex cases.
Trial registration
: Australian and New Zealand Clinical Trials Registry (anzctr.org.au) #ACTRN12618000623291.
Plain English summary
Lisdexamfetamine dimesylate (LDX) has been shown to reduce binge eating frequency among those with Binge Eating Disorder (BED). However, little is known about how LDX affects symptoms of common co-occurring conditions (ADHD, depression, anxiety) and mental health more broadly. In this study, 41 people with BED received an 8-week course of LDX and their symptoms were monitored before and after treatment. Overall, people experienced a robust improvement in eating disorder psychopathology and psychological quality of life. For those with higher levels of depression and ADHD, LDX had the additional benefit of improving depressive symptoms and inattentive symptom severity, respectively. The effect of LDX on anxiety symptoms appears to be more complex, with an equal proportion of people experiencing a decrease or an increase in anxiety over the course of treatment. Those who experienced reductions in anxiety during treatment tended to have greater concurrent reductions in binge eating frequency. This study provides preliminary evidence that for people with BED, LDX may be effective at improving co-occurring symptoms of eating disorder psychopathology and psychological well-being, and potentially ADHD and depression symptoms when present at an elevated level. More research is needed among a larger sample to verify these findings.
Journal Article
Understanding the neural mechanisms of lisdexamfetamine dimesylate (LDX) pharmacotherapy in Binge Eating Disorder (BED): a study protocol
by
Gomes, Linette
,
Korgaonkar, Mayuresh S.
,
Kohn, Michael R.
in
Adults
,
Analysis
,
Anorexia nervosa
2019
Background
The efficacy and safety of Lisdexamfetamine dimesylate (LDX) in the treatment of moderate to severe binge eating disorder (BED) has been demonstrated in multiple randomised clinical trials. Despite this, little is known about how LDX acts to improve binge eating symptoms. This study aims to provide a comprehensive understanding of the neural mechanisms by which LDX improves symptoms of BED. We hypothesise that LDX will act by normalising connectivity within neural circuits responsible for reward and impulse control, and that this normalisation will correlate with reduced binge eating episodes.
Methods
This is an open-label Phase 4 clinical trial of LDX in adults with moderate to severe BED. Enrolment will include 40 adults with moderate to severe BED aged 18–40 years and Body Mass Index (BMI) of 20–45 kg/m
2
, and 22 healthy controls matched for age, gender and BMI. Clinical interview and validated scales are used to confirm diagnosis and screen for exclusion criteria, which include comorbid anorexia nervosa or bulimia nervosa, use of psychostimulants within the past 6 months, and current use of antipsychotics or noradrenaline reuptake inhibitors. Baseline assessments include clinical symptoms, multimodal neuroimaging, cognitive assessment of reward sensitivity and behavioural inhibition, and an (optional) genetic sample. A subset of these assessments are repeated after eight weeks of treatment with LDX titrated to either 50 or 70 mg. The primary outcome measures are resting-state intrinsic connectivity and the number of binge eating episodes. Analyses will be applied to resting-state fMRI data to characterise pharmacological effects across the functional connectome, and assess correlations with symptom measure changes. Comparison of neural measures between controls and those with BED post-treatment will also be performed to determine whether LDX normalises brain function.
Discussion
First enrolment was in May 2018, and is ongoing. This study is the first comprehensive investigation of the neurobiological changes that occur with LDX treatment in adults with moderate to severe BED.
Trial registration
ACTRN12618000623291, Australian and New Zealand Clinical Trials Registry URL:
https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374913&isReview=true
. Date of Registration: 20 April 2018.
Journal Article