Functional neuroimaging in mood disorders

Cost-effectiveness of neuroimaging technologies in management of psychiatric and insomnia disorders: A meta-analysis and prospective cost analysis

BACKGROUND

The optimal diagnostic strategy for patients with psychiatric and insomnia disorders has not been established yet.

PURPOSE

The purpose of this study was to perform cost-effectiveness analysis of six neuroimaging technologies in diagnosis of patients with psychiatric and insomnia disorders.

METHODS

An economic evaluation study was conducted in three parts, including a systematic review for determining diagnostic accuracy, a descriptive cross-sectional study with Activity-Based Costing (ABC) technique for tracing resource consumption, and a cost-effectiveness analysis using a short-term decision-analytic model.

RESULTS

In the first phase, 93 diagnostic accuracy studies were included in the systematic review. The accumulated results (meta-analysis) showed that the highest diagnostic accuracy for psychiatric and insomnia disorders was attributed to PET (sensitivity of 90% and specificity of 80%) and MRI (sensitivity of 76% and specificity of 78%) respectively. In the second phase of the study, we calculated the cost of each technology. The results showed that MRI has the lowest cost. Based on the results in the model of cost-effectiveness sMRI ($ 50.08 per accurate diagnosis) and MRI ($ 58.54 per accurate diagnosis) were more cost-effective neuroimaging technologies.

CONCLUSION

In psychiatric disorders, no single strategy was characterized by both low cost and high accuracy. However, MRI and PET scan had lower cost and higher accuracy for psychiatric disorders, respectively. MRI was the least costly with the highest diagnostic accuracy in insomnia disorders. Based on our model, sMRI in psychiatric disorders and MRI in insomnia disorders were the most cost-effective technologies.

A genome-wide association study of amygdala activation in youths with and without bipolar disorder

OBJECTIVE

Functional magnetic resonance imaging is commonly used to characterize brain activity underlying a variety of psychiatric disorders. A previous functional magnetic resonance imaging study found that amygdala activation during a face-processing task differed between pediatric patients with bipolar disorder (BD) and healthy controls. We undertook a genome-wide association study to explore the genetic architecture of this neuroimaging phenotype.

METHOD

Thirty-nine patients with BD and 29 healthy controls who had previously undergone functional magnetic resonance imaging when viewing a neutral face were genotyped using a genome-wide single-nucleotide polymorphism (SNP) array. After quality control, 104,043 SNPs were tested against normalized amygdala activation scores obtained from the right and left hemispheres. Genetic association was tested with covariates to control for race and ethnicity. Patients and controls were grouped together in the primary analyses.

RESULTS

Right amygdala activation under the hostility contrast was most strongly associated with an SNP in the gene DOK5 (rs2023454, p = 4.88 x 10(-7), false discovery rate = 0.05). DOK5 encodes a substrate of tropomyosin-related kinase B/C receptors involved in neurotrophin signaling. This SNP accounted for about 33% of the variance in youths with BD and 12% of the variance in healthy youths. Other results (false discovery rate <50%) were also observed at SNPs near several other genes.

CONCLUSIONS

To our knowledge, this is the first genome-wide association study of amygdala activation in adolescents with BD. Although preliminary, these data suggest that DOK5 and perhaps several other genes influence the magnitude of amygdala activation during face processing, particularly in those with BD. Further studies are needed to replicate these findings and characterize the mechanisms involved.

A study of visuospatial working memory pre- and post-Gonadotropin Hormone Releasing Hormone agonists (GnRHa) in young women

Gonadotropin Hormone Releasing Hormone agonists (GnRHa) produce an acute decline in ovarian hormone production leading to a 'pseudo' menopause. This is therapeutically useful in the management of a variety of gynaecological conditions but also serves as a powerful model to study the effects of ovarian hormones on cognition. Animal and human behavioral studies report that memory is particularly sensitive to the effects ovarian hormone suppression (e.g. post GnRHa). Further, it has recently been reported that ovariectomy in young women increases the risk of cognitive impairment in later life. However, the underlying brain networks and/or stages of memory processing that might be modulated by acute ovarian hormone suppression remain poorly understood. We used event-related fMRI to examine the effect of GnRHa on visual working memory (VWM). Neuroimaging outcomes from 17 pre-menopausal healthy women were assessed at baseline and 8 weeks after GnRHa treatment. Seventeen matched wait-listed volunteers served as the control group and were assessed at similar intervals during the late follicular phase of the menstrual cycle. We report GnRHa was associated with attenuation of left parahippocampal (BA 35) and middle temporal gyri (BA 21 ,22, 39) activation, with a significant group-by-time interaction at left precuneus (BA 7) and posterior cingulate cortex (PCC) (BA 31) at encoding, and with cerebellar activation at recognition in the context of unimpaired behavioral responses. Our study suggests that acute ovarian hormone withdrawal following GnRHa, and perhaps at other times, (e.g. following surgical menopause and postpartum) alters the neural circuitry underlying performance of VWM.