Journal Article Annotations
2021, 3rd Quarter
Annotations by Brandon Francis MD, MPH
This case-control study of structural MRI findings for patients with high risk of psychotic-spectrum disorders found that those with decreased cortical thickness were at increased risk. Specifically, those with decreased cortical thickness in the right fusiform, left superior temporal and bilateral paracentral regions demonstrated increased conversion to a psychotic disorder.
Strength and weaknesses:
This study is the largest (3169 patients) using structural MRI to evaluate cortical thickness in patients having significant clinical risk factors for the development of psychotic disorders. It was an international multisite study, and differences in MRI scanners were controlled by using standard protocols and adjudication methods reported. The study focused on baseline assessments which limits the ability to understand any anatomic changes that may occur leading to or during the conversion to a psychotic disorder. The primary limitation inherent to this type of work relates to the reality that patients with clinical risk factors can have variable outcomes in different areas such as psychosocial functioning and other psychiatric illnesses such as anxiety. This study was not designed to capture the other areas of functioning that might be impacted by neuroanatomic changes such as cortical thickness.
Reduced cortical thickness has been associated with schizophrenia and other psychotic spectrum disorders. Utilizing structural MRI for clinical decision-making is not currently standard of care. However, understanding the potential influences of post-natal brain development may have on the development of psychotic disorders may one day provide a predictive anatomic diagnostic data point. Aligned with previous studies, no correlation was found with respect to subcortical volume changes and psychosis.
This multisite population-based observational study (no control group) used the EPIBipolar semi-structured interview tool to risk stratify patients into no risk, low risk or high risk for bipolar disorder. T1-weighted (and some functional) sequences were obtained. Patients with diagnosed bipolar disorder, schizophrenia or other psychotic disorders were excluded. They also excluded those with substance-dependence disorders that fully explained the patient’s symptoms. They evaluated 263 patients and found a significant difference in the cortical thickness of the left infero-frontal pars opercularis between high risk and no risk groups. Those with high risk demonstrated a thinner cortex (p = < 0.024).
Strength and weaknesses:
Each of the seven different sites that participated attempted to use similar protocols for each sequence of interest. However, the software and hardware were not identical among sites. This study used a structured tool to stratify patients at risk of development of bipolar disorder. The primary limitation of the study was the lack of follow up to ascertain which patients actually developed bipolar disorder. While the findings are aligned with cortical thickness changes previously reported in patients with bipolar disorder, long-term follow up would be helpful in more clearly demonstrating a functional relationship between cortical thickness and diagnostic outcomes.
The infero-frontal gyrus (pars opercularis) has been implicated in emotional dysregulation and may play an important part in mood disorders. This study highlights the role that neuroimaging may play in assisting the C-L Psychiatrist in identifying patients at risk. While not standard of care, neuroimaging may represent an untapped diagnostic resource for those caring for patients at high risk for bipolar disorder.
This single site, observational study evaluated neuroanatomic changes using a 3 Tesla MRI with 45 patients (from ages 13-, mean 26 years) who have schizophrenia and were admitted to a psychiatric hospital. The investigators found enlargement of Virchow’s spaces (97% of those with schizophrenia), sinusitis (60%) and demyelinating lesions (36%).
Strength and weaknesses:
This study reported a lower rate cortical atrophy (9% of patients) compared to prior studies, which may reflect the high proportion of pediatric patients in the study. They also included patients who were actively taking antipsychotic medications without controlling for the duration of that treatment. The effect of antipsychotic psychopharmacology on MRI brain anatomy has not been fully explored, rendering the data presented in this study difficult to interpret. The study is also relatively small and without any comparative imaging, it is difficult to determine if there were any temporal relationships that need to be considered.
MRI sequences can provide accurate neuroanatomic information in patients with schizophrenia. While not standard of care, in the future, MRI may assist in the differential diagnosis, prognosis and follow up for patients with schizophrenia. More study is needed with respect to effect of pharmacotherapy (and substance use) on these neuroanatomic changes in this population as well as comparative imaging such that longitudinal relationships can be explored.