Objective: The right hemisphere of the brain plays a significant role in the experience and expression of emotions and is often deregulated in psychiatric patients. The thalamus influences cortical and subcortical activity in both hemispheres via widespread thalamocortical/cortiocothalamic projections. Asymmetrical thalamic activity may impact function in one hemisphere. In our population of psychiatric patients studied with a combination of positron emission tomography (PET) and quantitative EEG (qEEG), most patients demonstrated reduced metabolic activity in their right thalamus. We hypothesized greater right-sided (R<L) thalamic asymmetry in metabolic activity would significantly correlate with focal EEG abnormalities in the right hemisphere.
Methods: We analyzed archival PET and qEEG data of 48 patients from a community-based psychiatric outpatient clinic. Patients presented with a variety of symptoms, often with complex and comorbid diagnoses. Statistical evaluation for PET images was obtained with BRASS software (HERMES software, total count adjustment). Significant focal EEG abnormalities were identified using low-resolution brain electromagnetic tomography (LORETA). Significance was set at ±2 standard deviations. Independent t-tests (p<0.05) were utilized to compare percent differences between right and left thalamic count/voxel ratios as well as normalized asymmetry z-scores between patients with focal EEG abnormalities in the right hemisphere and those without.
Results: Thirty-five (n=35) patients demonstrated decreased activity in the right thalamus as compared to the left. Of these patients, twelve (n=12) demonstrated one or more right-hemispheric focal EEG abnormalities in theta (.) frequencies and twenty-three (n=23) did not have any right-sided focal . findings. A significant difference was found in percent difference of right/left metabolic activity between patients with right focal . abnormalities (M=8.90, SD=4.92) and those without (M=5.36, SD=4.07); t = -2.268, p = 0.030. There was also a significant difference in normalized asymmetry z-scores for patients with right focal . abnormalities (M=3.31, SD=1.49) and those without (M=2.00, SD=1.38); t = -2.590, p = 0.014.
Conclusions: The findings support the hypothesis in that right-sided thalamic asymmetry is correlated to presence of right-hemispheric focal . abnormalities in EEG. The results offer implications for relationships between thalamic function and electrophysiological activity. This study supports a multimodality approach combining nuclear imaging and EEG to enhance identification of abnormal function in psychiatric patients.
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A mental health condition that’s characterized by intense shifts in mood including both manic and depressive episodes.
People living with Major Depressive Disorder, or MDD, experience episodes of depression and sadness that are debilitating to daily life.
Those living with anxiety disorders experience high levels of anxiety and stress that interfere negatively with daily life.
A mental health issue in which a person’s cognitive function is impaired, resulting in symptoms like experiencing challenges with conducting speech, reading and writing, and behavior.
Mental health disorders that negatively affect a person’s behaviors, thought patterns, and function. People diagnosed with these disorders experience challenges with managing relationships and understanding various situations.
Post-Traumatic Stress Disorder is a mental health condition that people can develop as a result of experiencing traumatic situations, characterized by symptoms including flashbacks, avoidance behaviors, and more.
A mental health condition that is characterized by specific symptoms of forgetfulness and lack of concentration, which makes it challenging to complete necessary tasks.
Mental health conditions that interfere with a person’s eating habits, thought patterns, and behaviors in negative ways.
A mental health disorder diagnosable with the DSM-5 that is characterized by both obsessions and compulsive behaviors.