Ronak Patel

• Doctor of Psychology
• Board Certified Clinical Neuropsychologist & Assistant Professor at University of Manitoba

Introduction Crohn's disease is one phenotype of inflammatory bowel disease (IBD). Fatigue is a common and burdensome symptom for persons with Crohn's disease. Despite its detrimental impact on health-related quality of life, the pathophysiology of fatigue in Crohn's disease is not fully understood. Specifically, basic research on the difference in...

Lay Summary Persons with inflammatory bowel disease exhibit a weaker relationship between executive function and functional connectivity of cerebellar regions (VIIa Crus I and VIIa Crus II) to cortical areas involved in visual processing compared to healthy counterparts with comparable performance.

The Canadian Stroke Best Practice Recommendations (CSPR) 7th edition includes this new module on the diagnosis and management of vascular cognitive impairment (VCI) with or without neurodegenerative disease. An expert writing group and people with VCI lived experience (PWLE) reviewed current evidence. Existing recommendations were reviewed and revi...

Introduction Posttraumatic stress disorder (PTSD) is a mental health disorder caused by experiencing or witnessing traumatic events. Recent studies show that patients with PTSD have an increased risk of developing dementia, including Alzheimer's disease (AD), but there is currently no way to predict which patients will go on to develop AD. The obje...

Background People with multiple sclerosis (MS) have an increased risk of ischemic heart disease as compared to people without MS after accounting for traditional vascular risk factors. Objective We assessed whether subclinical atherosclerosis, an inflammatory disease of arteries, occurs in persons with MS who do not have traditional vascular risk...

Background Fifty-one percent of individuals with multiple sclerosis (MS) develop cognitive impairment (CI) in information processing speed (IPS). Although IPS scores are associated with health and well-being, neural changes that underlie IPS impairments in MS are not understood. Resting state fMRI can provide insight into brain function changes und...

Background Vascular disease and cognitive impairment have been increasingly documented in inflammatory bowel disease (IBD), and both have been individually correlated with changes in brain structure. This study aimed to determine if both macro- and microstructural brain changes are prevalent in IBD and whether alterations in brain structure mediate...

Reports of cognitive impairment in inflammatory bowel disease (IBD) have been mixed. IBD and cardiovascular disease are often co-morbid, yet it remains unknown whether vascular comorbidity confers a risk for decreased cognitive functioning, as observed in other populations. Participants with IBD were recruited from a longitudinal study of immune-me...

Previous work has shown recognition of emotional facial expressions may differentially relate to task demands, such as whether one indirectly or directly encodes the emotional information. Given gender differences in emotion processing and memory, we assessed whether participant gender might moderate these encoding task effects. Using a between-sub...

Background: Reports of cognitive impairment in inflammatory bowel disease (IBD) have been mixed. IBD and cardiovascular disease are often co-morbid, yet it remains unknown whether vascular comorbidity confers a risk for decreased cognitive functioning, as observed in other populations. Methods: Participants with IBD were recruited from a longitudin...

Objective Anti-leucine-rich glioma-inactivated 1 limbic encephalitis (LGI1-LE) is a rare autoimmune condition that affects the structural integrity and functioning of the brain’s limbic system. Little is known about its impact on long-term neuropsychological functioning and the structural integrity of the medial temporal lobe. Here we examined the...

The Comorbidity and Cognition in Multiple Sclerosis (CCOMS) study represents a coordinated effort by a team of clinicians, neuropsychologists, and neuroimaging experts to investigate the neural basis of cognitive changes and their association with comorbidities among persons with multiple sclerosis (MS). The objectives are to determine the relation...

Objective Vascular comorbidities are associated with reduced cognitive performance and with changes in brain structure in people with multiple sclerosis (MS). Understanding causal pathways is necessary to support the design of interventions to mitigate the impacts of comorbidities, and to monitor their effectiveness. We assessed the inter-relations...

Posttraumatic stress disorder (PTSD) is a prevalent psychiatric disorder that can result from experiencing traumatic events. Accurate diagnosis and optimal treatment strategies can be difficult to achieve, due to the heterogeneous etiology and symptomology of PTSD, and overlap with other psychiatric disorders. Advancing our understanding of PTSD pa...

Memory is better for emotional rather than neutral events or materials (emotional enhancement of memory; EEM). Evidence suggests that this memory benefit remains intact in schizophrenia, but conflicting findings present the need for further research to understand how and when this process occurs. Here, we examine whether different encoding methods...

Background : Few studies have evaluated the association between comorbidities associated with increased vascular risk and brain volume changes in multiple sclerosis (MS). To date, findings have not been consistent with respect to which comorbidities are associated with lower brain volumes or whether comorbidities associated with increased vascular...

Background: Cognitive impairment is common in multiple sclerosis (MS). Interpretation of neuropsychological tests requires the use of normative data. Traditionally, normative data have been reported for discrete categories such as age. More recently continuous norms have been developed using multivariable regression equations that account for multi...

Background Longitudinal studies assessing depression and anxiety effects on cognition in multiple sclerosis (MS) are limited. Objective We tested whether within-person fluctuations in symptoms of depression or anxiety over time affect cognition in persons with MS, inflammatory bowel disease (IBD), rheumatoid arthritis (RA), and a lifetime history...

Repetitive transcranial magnetic stimulation (rTMS) is thought to modulate brain function through methods of electromagnetic induction. Over the last few decades, a large body of studies have investigated the clinical applications of rTMS in a variety of patient populations for a diverse range of symptoms from depressive symptomology to post-stroke...

Background: Spatially normalizing brain MRI data to a template is commonly performed to facilitate comparisons between individuals or groups. However, the presence of multiple sclerosis (MS) lesions and other MS-related brain pathologies may compromise the performance of automated spatial normalization procedures. We therefore aimed to systematica...

Objective To determine whether comorbid diabetes and hypertension are associated with cognition in multiple sclerosis (MS) after accounting for psychiatric comorbidities. Methods Participants completed a structured psychiatric interview, the Hospital Anxiety and Depression Scale (HADS), a comorbidity questionnaire, and cognitive testing including...

Background: Posttraumatic stress disorder (PTSD) is associated with abnormal hippocampal activity; however, the functional connectivity (FC) of the hippocampus with other brain regions in PTSD and its relations with symptoms warrants further attention. We investigated subregional hippocampal FC in PTSD during a resting state compared with a trauma...

Explanation for intracranial steal demonstrated with the BOLD MRI CO2 stress test as described in this study. (A) The CO2 stress administered is shown at the bottom of the panel. This was an 11-minute stimulus (660 s). A block design triple hypercapnic stimulus each of 2 min at 5 mm Hg increase in CO2 was interspersed with baseline end-tidal CO2. I...

This video depicts the dynamic response of the human brain to alterations in end-tidal CO2 tension. The left panel shows the CO2 stimulus over time. The CO2 delta here is approximately 20 mmHg—the upper limit of change in CO2 seen in this study. The right panel shows the changes in BOLD CVR to the CO2 stimulus. The signal changes to an essentially...

The end-tidal gases for each subject are shownbaseline CO2 (CO2 BL), CO2 delta, and mean O2 in mm Hg. A comparison between the non-POD and combined ST-POD- and POD-values and t-statistics are also shown.

A glossary of anesthesia terms relating to gas exchange and intracranial steal.

Introduction: Risk assessment for post-operative delirium (POD) is poorly developed. Improved metrics could greatly facilitate peri-operative care as costs associated with POD are staggering. In this preliminary study, we develop a novel stress-diathesis model based on comprehensive pre-operative psychiatric and neuropsychological testing, a blood...

Background: The vast majority of functional neuroimaging studies in posttraumatic stress disorder (PTSD) have examined the amygdala as a unitary structure. However, an emerging body of studies indicates that separable functions are subserved by discrete amygdala subregions. The basolateral subdivision (BLA), as compared with the centromedial amygd...

Previous empirical work suggests that emotion can influence accuracy and cognitive biases underlying recognition memory, depending on the experimental conditions. The current study examines the effects of arousal and valence on delayed recognition memory using the diffusion model, which allows the separation of two decision biases thought to underl...

Model Fit for Arousal at 1-day Delay. Fit of the model predictions for response time quartiles and accuracy values for high and low arousal at the 1-day delay. (TIF)

Model Fit for Arousal at 7-day Delay. Fit of the model predictions for response time quartiles and accuracy values for high and low arousal at the 7-day delay. (TIF)

Model Fit for Valence at 7-day Retention. Fit of model predictions for response time quartiles and accuracy values for negative and positive valence at the 7-day delay. (TIF)

Model Fit for Valence at 1-day Delay. Fit of model predictions for response time quartiles and accuracy values for negative and positive valence at the 1-day delay. (TIF)

All possible two-subtest combinations of the core Wechsler Adult Intelligence Scale–IV (WAIS-IV) subtests were evaluated as possible viable short forms for estimating full-scale IQ (FSIQ). Validity of the dyads was evaluated relative to FSIQ in a large clinical sample (N = 482) referred for neuropsychological assessment. Sample validity measures in...

The lateral septum (LS) is implicated in behavioral defense. We tested whether bilateral infusions of the GABAA receptor agonist muscimol into the LS suppress rats' defensive responses to cat odor. Rats received intra-LS infusions of either saline or muscimol (40ng/rat) and were exposed to either a piece of a cat collar that had been previously wor...

The lateral septum (LS) is implicated in behavioral defense. We tested whether bilateral infusions of the GABAA receptor agonist muscimol into the LS suppress rats' defensive responses to cat odor. Rats received intra-LS infusions of either saline or muscimol (40ng/rat) and were exposed to either a piece of a cat collar that had been previously wor...

Background: Functional neuroimaging is increasingly used in rehabilitation research to map the neural mechanisms subserving training targets. These data can inform intervention design and improve evaluation of treatment outcomes. Reliable neural markers may provide standard metrics of treatment impact and allow consideration of behavioral outcomes...

We used the Remember–Know procedure (Tulving, 198524. Tulving , E. 1985. Memory and consciousness. Canadian Psychology, 26: 1–12. [CrossRef], [Web of Science ®]View all references) to test the behavioural expression of memory following indirect and direct forms of emotional processing at encoding. Participants (N=32) viewed a series of facial expr...

This thesis examines whether implicit and explicit processing of emotional facial expressions affects the emotional enhancement of memory (EEM). On the basis that explicit processing is associated with relative reductions in amygdala activation and arousal, I predicted that fearful faces, in particular, would lead to a robust EEM effect following e...