Phillip Adams

Cortical thinning in persons at increased familial risk for major depression

The brain disturbances that place a person at risk for developing depression are unknown. We imaged the brains of 131 individuals, ages 6 to 54 years, who were biological descendants (children or grandchildren) of individuals identified as having either moderate to severe, recurrent, and functionally debilitating depression or as having no lifetime history of depression. We compared cortical thickness across high- and low-risk groups, detecting large expanses of cortical thinning across the lateral surface of the right cerebral hemisphere in persons at high risk. Thinning correlated with measures of current symptom severity, inattention, and visual memory for social and emotional stimuli. Mediator analyses indicated that cortical thickness mediated the associations of familial risk with inattention, visual memory, and clinical symptoms. These findings suggest that cortical thinning in the right hemisphere produces disturbances in arousal, attention, and memory for social stimuli, which in turn may increase the risk of developing depressive illness.

Association of a polyadenylation polymorphism in the serotonin transporter and panic disorder.

BACKGROUND Genetic markers in the serotonin transporter are associated with panic disorder (PD). The associated polymorphisms do not include the serotonin transporter-linked polymorphic region and display no obvious functional attributes. A common polymorphism (rs3813034) occurs in one of the two reported polyadenylation signals for the serotonin transporter and is in linkage disequilibrium with the PD-associated markers. If functional, rs3813034 might be the risk factor that explains the association of the serotonin transporter and PD. METHODS Quantitative polymerase chain reaction on human brain samples (n = 65) and lymphoblast cultures (n = 71) was used to test rs3813034 for effects on expression of the polyadenylation forms of the serotonin transporter. rs3813034 was also tested for association in a sample of PD cases (n = 307) and a control sample (n = 542) that has similar population structure. RESULTS The balance of the two polyadenylation forms of the serotonin transporter is associated with rs3813034 in brain (p < .001) and lymphoblasts (p < .001). The balance of the polyadenylation forms is also associated with gender in brain only (p < .05). Association testing of rs3813034 in PD identified a significant association (p = .0068) with a relative risk of 1.56 and 1.81 for the heterozygous and homozygous variant genotypes, respectively. CONCLUSIONS rs3813034 is a functional polymorphism in the serotonin transporter that alters the balance of the two polyadenylation forms of the serotonin transporter. rs3813034 is a putative risk factor for PD and other behavioral disorders that involve dysregulation of serotonergic neurotransmission.

Test-retest reliability of freesurfer measurements within and between sites: Effects of visual approval process

In the last decade, many studies have used automated processes to analyze magnetic resonance imaging (MRI) data such as cortical thickness, which is one indicator of neuronal health. Due to the convenience of image processing software (e.g., FreeSurfer), standard practice is to rely on automated results without performing visual inspection of intermediate processing. In this work, structural MRIs of 40 healthy controls who were scanned twice were used to determine the test–retest reliability of FreeSurfer‐derived cortical measures in four groups of subjects—those 25 that passed visual inspection (approved), those 15 that failed visual inspection (disapproved), a combined group, and a subset of 10 subjects (Travel) whose test and retest scans occurred at different sites. Test–retest correlation (TRC), intraclass correlation coefficient (ICC), and percent difference (PD) were used to measure the reliability in the Destrieux and Desikan–Killiany (DK) atlases. In the approved subjects, reliability of cortical thickness/surface area/volume (DK atlas only) were: TRC (0.82/0.88/0.88), ICC (0.81/0.87/0.88), PD (0.86/1.19/1.39), which represent a significant improvement over these measures when disapproved subjects are included. Travel subjects’ results show that cortical thickness reliability is more sensitive to site differences than the cortical surface area and volume. To determine the effect of visual inspection on sample size required for studies of MRI‐derived cortical thickness, the number of subjects required to show group differences was calculated. Significant differences observed across imaging sites, between visually approved/disapproved subjects, and across regions with different sizes suggest that these measures should be used with caution. Hum Brain Mapp 36:3472–3485, 2015.

Neural Correlates of Three Promising Endophenotypes of Depression: Evidence from the EMBARC Study

Major depressive disorder (MDD) is clinically, and likely pathophysiologically, heterogeneous. A potentially fruitful approach to parsing this heterogeneity is to focus on promising endophenotypes. Guided by the NIMH Research Domain Criteria initiative, we used source localization of scalp-recorded EEG resting data to examine the neural correlates of three emerging endophenotypes of depression: neuroticism, blunted reward learning, and cognitive control deficits. Data were drawn from the ongoing multi-site EMBARC study. We estimated intracranial current density for standard EEG frequency bands in 82 unmedicated adults with MDD, using Low-Resolution Brain Electromagnetic Tomography. Region-of-interest and whole-brain analyses tested associations between resting state EEG current density and endophenotypes of interest. Neuroticism was associated with increased resting gamma (36.5–44 Hz) current density in the ventral (subgenual) anterior cingulate cortex (ACC) and orbitofrontal cortex (OFC). In contrast, reduced cognitive control correlated with decreased gamma activity in the left dorsolateral prefrontal cortex (dlPFC), decreased theta (6.5–8 Hz) and alpha2 (10.5–12 Hz) activity in the dorsal ACC, and increased alpha2 activity in the right dlPFC. Finally, blunted reward learning correlated with lower OFC and left dlPFC gamma activity. Computational modeling of trial-by-trial reinforcement learning further indicated that lower OFC gamma activity was linked to reduced reward sensitivity. Three putative endophenotypes of depression were found to have partially dissociable resting intracranial EEG correlates, reflecting different underlying neural dysfunctions. Overall, these findings highlight the need to parse the heterogeneity of MDD by focusing on promising endophenotypes linked to specific pathophysiological abnormalities.

Discriminating Risk and Resilience Endophenotypes From Lifetime Illness Effects in Familial Major Depressive Disorder

IMPORTANCE The neural systems that confer risk or vulnerability for developing familial depression, and those that protect against or confer resilience to becoming ill, can be disentangled from the effects of prior illness by comparing brain imaging measures in previously ill and never ill persons who have either a high or low familial risk for depression. OBJECTIVE To distinguish risk and resilience endophenotypes for major depression from the effects of prior lifetime illness. DESIGN, SETTING, AND PARTICIPANTS We used functional magnetic resonance imaging to measure and compare brain function during performance of an attentional, self-regulatory task across a large sample of multigenerational families ascertained specifically to be at either high or low risk for developing major depression. Study procedures were performed in a university setting. A total of 143 community participants were followed up prospectively for more than 20 years in a university setting. The sample was enriched with persons who were at higher or lower familial risk for developing depression based on being biological offspring of either a clinical sample of persons with major depression or a community control sample of persons with no discernible lifetime illness. MAIN OUTCOMES AND MEASURES Task-related change in blood oxygen level-dependent functional magnetic resonance imaging signal. RESULTS A risk endophenotype included greater activation of cortical attention circuits. A resilience endophenotype included greater activation of the dorsal anterior cingulate cortex. The effects of prior lifetime illness were common to both risk groups and included greater deactivation of default-mode circuits. CONCLUSIONS AND RELEVANCE These findings identify neural systems that increase risk for depression, those that protect from illness, and those that endure following illness onset, and they suggest circuits to target for developing novel preventive and therapeutic interventions.

Panic disorder with smothering symptoms: Evidence for increased risk in first-degree relatives

Kleins (1993: Arch Gen Psychiatry 50:306–317) “false suffocation alarm” theory of spontaneous panic attacks posits that central receptors compare CO2, O2, and lactate levels and trigger panic when an impending “false” state of suffocation is detected. Several investigators have found abnormalities of respiratory physiology in subjects with panic disorder. Twin and family studies have suggested that both panic disorder and tidal volume response to CO2 are inherited. We hypothesized that, if smothering symptoms are a marker for a hypersensitive suffocation detector and if this hypersensitivity is familial, then relatives of panic subjects with smothering symptoms would have higher rates of panic with smothering than relatives of panic subjects without smothering. We conducted a family study involving 104 panic disorder probands and 247 of their interviewed first‐degree relatives. Probands and their relatives were interviewed using the Schedule for Affective Disorders and Schizophrenia—Lifetime Version for Anxiety Disorders to determine their panic disorder and smothering symptom status. Relatives of panic probands with smothering symptoms had an almost threefold higher risk for panic and an almost sixfold higher risk for panic with smothering symptoms when compared with relatives of panic probands without smothering. We conclude that panic disorder with smothering symptoms may be a subtype of panic disorder associated with increased familial risk and may be a group of interest to genetic investigators. These findings provide the first empiric evidence from a family study in support of Kleins false suffocation alarm theory of spontaneous panics. Depression and Anxiety 6:147–153, 1997.

Test-retest reliability of freesurfer measurements within and between sites

In the last decade, many studies have used automated processes to analyze magnetic resonance imaging (MRI) data such as cortical thickness, which is one indicator of neuronal health. Due to the convenience of image processing software (e.g., FreeSurfer), standard practice is to rely on automated results without performing visual inspection of intermediate processing. In this work, structural MRIs of 40 healthy controls who were scanned twice were used to determine the test–retest reliability of FreeSurfer‐derived cortical measures in four groups of subjects—those 25 that passed visual inspection (approved), those 15 that failed visual inspection (disapproved), a combined group, and a subset of 10 subjects (Travel) whose test and retest scans occurred at different sites. Test–retest correlation (TRC), intraclass correlation coefficient (ICC), and percent difference (PD) were used to measure the reliability in the Destrieux and Desikan–Killiany (DK) atlases. In the approved subjects, reliability of cortical thickness/surface area/volume (DK atlas only) were: TRC (0.82/0.88/0.88), ICC (0.81/0.87/0.88), PD (0.86/1.19/1.39), which represent a significant improvement over these measures when disapproved subjects are included. Travel subjects’ results show that cortical thickness reliability is more sensitive to site differences than the cortical surface area and volume. To determine the effect of visual inspection on sample size required for studies of MRI‐derived cortical thickness, the number of subjects required to show group differences was calculated. Significant differences observed across imaging sites, between visually approved/disapproved subjects, and across regions with different sizes suggest that these measures should be used with caution. Hum Brain Mapp 36:3472–3485, 2015.

Accounting for Dynamic Fluctuations across Time when Examining fMRI Test-Retest Reliability: Analysis of a Reward Paradigm in the EMBARC Study.

Longitudinal investigation of the neural correlates of reward processing in depression may represent an important step in defining effective biomarkers for antidepressant treatment outcome prediction, but the reliability of reward-related activation is not well understood. Thirty-seven healthy control participants were scanned using fMRI while performing a reward-related guessing task on two occasions, approximately one week apart. Two main contrasts were examined: right ventral striatum (VS) activation fMRI BOLD signal related to signed prediction errors (PE) and reward expectancy (RE). We also examined bilateral visual cortex activation coupled to outcome anticipation. Significant VS PE-related activity was observed at the first testing session, but at the second testing session, VS PE-related activation was significantly reduced. Conversely, significant VS RE-related activity was observed at time 2 but not time 1. Increases in VS RE-related activity from time 1 to time 2 were significantly associated with decreases in VS PE-related activity from time 1 to time 2 across participants. Intraclass correlations (ICCs) in VS were very low. By contrast, visual cortex activation had much larger ICCs, particularly in individuals with high quality data. Dynamic changes in brain activation are widely predicted, and failure to account for these changes could lead to inaccurate evaluations of the reliability of functional MRI signals. Conventional measures of reliability cannot distinguish between changes specified by algorithmic models of neural function and noisy signal. Here, we provide evidence for the former possibility: reward-related VS activations follow the pattern predicted by temporal difference models of reward learning but have low ICCs.

A computational analysis of flanker interference in depression

BACKGROUND Depression is characterized by poor executive function, but - counterintuitively - in some studies, it has been associated with highly accurate performance on certain cognitively demanding tasks. The psychological mechanisms responsible for this paradoxical finding are unclear. To address this issue, we applied a drift diffusion model (DDM) to flanker task data from depressed and healthy adults participating in the multi-site Establishing Moderators and Biosignatures of Antidepressant Response for Clinical Care for Depression (EMBARC) study. METHOD One hundred unmedicated, depressed adults and 40 healthy controls completed a flanker task. We investigated the effect of flanker interference on accuracy and response time, and used the DDM to examine group differences in three cognitive processes: prepotent response bias (tendency to respond to the distracting flankers), response inhibition (necessary to resist prepotency), and executive control (required for execution of correct response on incongruent trials). RESULTS Consistent with prior reports, depressed participants responded more slowly and accurately than controls on incongruent trials. The DDM indicated that although executive control was sluggish in depressed participants, this was more than offset by decreased prepotent response bias. Among the depressed participants, anhedonia was negatively correlated with a parameter indexing the speed of executive control (r = -0.28, p = 0.007). CONCLUSIONS Executive control was delayed in depression but this was counterbalanced by reduced prepotent response bias, demonstrating how participants with executive function deficits can nevertheless perform accurately in a cognitive control task. Drawing on data from neural network simulations, we speculate that these results may reflect tonically reduced striatal dopamine in depression.

A survey of putative anxiety-associated genes in panic disorder patients with and without bladder symptoms.

Background We have previously described a subtype of panic disorder (PD) that we termed ‘bladder syndrome’, characterized by urological and bladder symptoms (and possibly interstitial cystitis) in the patients and/or their family members and confirmed the validity of this subset in family linkage and association analysis. In this study, we determine (a) whether 20 single-nucleotide polymorphisms (SNPs) reported in the literature can be replicated in a new PD dataset and (b) whether dividing the sample into those with and without the ‘bladder syndrome’ can help to resolve the genetic heterogeneity within this new sample. Methods We selected 20 putative associated SNPs from the literature, taken from studies published since 2004. We tested these SNPs for association in a sample of 351 PD patients and 552 controls, and then divided them into subgroups of 92 patients from bladder families and 259 from nonbladder families. Results (a) When analyzed in all PD patients, none of the 20 SNPs appeared to be replicated (except for SLC6A4 from our previous study, but in a sample that overlaps substantially with that in our previous report). (b) However, some intriguing findings emerged when we separated bladder from nonbladder families: SLC6A4, reported by us previously, yielded stronger evidence than before (P=0.0018) when examined only in nonbladder families, and in contrast, is not statistically significant in bladder families. Two other markers yielded nominally significant results in bladder families – rs5751876 in ADORA2A (P=0.046) and rs12579350 in TMEM16B (P=0.035) – but were not significant in nonbladder families. (c) Two markers had noticeably lower P-values when we differentiated the women and analyzed them separately – rs12579350 in TMEM16B (P-value decreased from 0.035, as above, to 0.00055) and a different SNP in ADORA2A, rs4822492 (P-value decreases from 0.07 to 0.028). Significance Our results indicate that most of the 20 reported associations do not hold up when PD is analyzed as one group. However, our findings provide further evidence that PD with bladder symptoms may be genetically different from PD without bladder. We suggest that it is worth pursuing SLC6A4 in nonbladder PD, and ADORA2A and TMEM16B in bladder PD. Also, the possibility of a male–female difference in PD is worth pursuing. We also briefly discuss issues of replication and multiple tests.