High-dimensional Factor Analysis for Network-linked Data

Factor analysis is a widely used statistical tool in many scientific disciplines, such as psychology, economics, and sociology. As observations linked by networks become increasingly common, incorporating network structures into factor analysis remains an open problem. In this paper, we focus on high-dimensional factor analysis involving network-connected observations, and propose a generalized factor model with latent factors that account for both the network structure and the dependence structure among high-dimensional variables. These latent factors can be shared by the high-dimensional variables and the network, or exclusively applied to either of them. We develop a computationally efficient estimation procedure and establish asymptotic inferential theories. Notably, we show that by borrowing information from the network, the proposed estimator of the factor loading matrix achieves optimal asymptotic variance under much milder identifiability constraints than existing literature. Furthermore, we develop a hypothesis testing procedure to tackle the challenge of discerning the shared and individual latent factors' structure. The finite sample performance of the proposed method is demonstrated through simulation studies and a real-world dataset involving a statistician co-authorship network

The Changes of Functional Connectivity Strength in Electroconvulsive Therapy for Depression: A Longitudinal Study

Electroconvulsive therapy (ECT) is an effective treatment for depression, but the mechanism of ECT for depression is still unclear. Recently, neuroimaging studies have reported that the prefrontal cortex, hippocampus, angular gyrus, insular and other brain regions are involved in the mechanism of ECT for depression, and these regions are highly overlapped with the location of brain hubs. Here, we try to explore the effects of ECT on the functional connectivity of brain hubs in depression patients. In current study, depression patients were assessed at three time points: prior to ECT, at the completion of ECT and about 1 month after the completion of ECT. At each time point, resting-state functional magnetic resonance imaging, assessment of clinical symptoms and cognition function were performed respectively, which was compared with 20 normal controls. Functional connectivity strength (FCS) was used to identify brain hubs. The results showed that FCS of left angular gyrus in depression patients significantly increased after ECT, accompanied by improved mood. The changed FCS in depression patients recovered obviously at 1 month after the completion of ECT. It suggested that ECT could modulate functional connectivity of left angular gyrus in depression patients

Mixed response to the first‐line treatment of KRAS G12C inhibitor, sotorasib, in non‐small cell lung cancer: A brief report

Key Clinical Message One Kirsten Ras (KRAS) G12C mutated non‐small cell lung cancer (NSCLC) patient had improved poor performance status and obtained mixed response with the first‐line KRAS‐targeted treatment of sotorasib. After disease progression, partial response was achieved with chemotherapy plus immunotherapy. KRAS G12C mutated immunoenvironment in NSCLC may favor the immunotherapy. Abstract KRAS is one of the most commonly mutated genes, which used to be untargetable. The phase II CodeBreak 100 trial revealed 6.8‐month median progress‐free survival (PFS) and 12.5‐month overall survival (OS) in previously treated KRAS G12C‐mutant NSCLC patients treated with KRAS inhibitor, sotorasib. The specimens of the brain, lymph node (LN), and blood from the patient were analyzed by next‐generation sequencing. Hematoxylin and eosin staining and immunohistochemistry were performed for pathological characterization. Computed tomography (CT) and magnetic resonance imaging (MRI) scan were used for treatment response evaluation. The patient was diagnosed in a bad Eastern Cooperative Oncology Group performance status (ECOG‐PS) with metastatic KRAS G12C‐mutated lung adenocarcinoma who had achieved mixed response to sotorasib as the first‐line treatment. Although 5‐month PFS of the treatment with sotorasib was not surprising, the patient achieved significantly improved ECOG‐PS score from 4 to 1. Subsequently, partial response (PR) was achieved with the treatment of pemetrexed plus pembrolizumab. This case highlights superior efficacy of first‐line treatment with sotorasib for the advance untreated KRAS G12C‐mutant patients. The high efficacy of the treatment with chemotherapy plus immunotherapy revealed that immunoenvironment of KRAS G12C‐mutated patient may favor the immunotherapy

Changes in Thalamic Connectivity in the Early and Late Stages of Amnestic Mild Cognitive Impairment: A Resting-State Functional Magnetic Resonance Study from ADNI

<div><p>We used resting-state functional magnetic resonance imaging (fMRI) to investigate changes in the thalamus functional connectivity in early and late stages of amnestic mild cognitive impairment. Data of 25 late stages of amnestic mild cognitive impairment (LMCI) patients, 30 early stages of amnestic mild cognitive impairment (EMCI) patients and 30 well-matched healthy controls (HC) were analyzed from the Alzheimer’s disease Neuroimaging Initiative (ADNI). We focused on the correlation between low frequency fMRI signal fluctuations in the thalamus and those in all other brain regions. Compared to healthy controls, we found functional connectivity between the left/right thalamus and a set of brain areas was decreased in LMCI and/or EMCI including right fusiform gyrus (FG), left and right superior temporal gyrus, left medial frontal gyrus extending into supplementary motor area, right insula, left middle temporal gyrus (MTG) extending into middle occipital gyrus (MOG). We also observed increased functional connectivity between the left/right thalamus and several regions in LMCI and/or EMCI including left FG, right MOG, left and right precuneus, right MTG and left inferior temporal gyrus. In the direct comparison between the LMCI and EMCI groups, we obtained several brain regions showed thalamus-seeded functional connectivity differences such as the precentral gyrus, hippocampus, FG and MTG. Briefly, these brain regions mentioned above were mainly located in the thalamo-related networks including thalamo-hippocampus, thalamo-temporal, thalamo-visual, and thalamo-default mode network. The decreased functional connectivity of the thalamus might suggest reduced functional integrity of thalamo-related networks and increased functional connectivity indicated that aMCI patients could use additional brain resources to compensate for the loss of cognitive function. Our study provided a new sight to understand the two important states of aMCI and revealed resting-state fMRI is an appropriate method for exploring pathophysiological changes in aMCI.</p></div

Agenda and attachments, November 14, 2012

<p>Abbreviations: STG = superior temporal gyrus; mFG = medial frontal gyrus; SMA = supplementary motor area; ITG = inferior temporal gyrus; FG = fusiform gyrus; MTG = middle temporal gyrus; MOG = middle occipital gyrus; PCu = precuneus; R = right side; L = left side; BA = Brodmann’s area; BA = Brodmann’s area; N/A = not applicable.</p><p><b><i>T</i></b>: functional connectivity strength of the left/right thalamus and <i>T</i> value was obtained by a one sample t-test; <b><i>CC</i></b>: correlation coefficient; <b>“↓+":</b> decrease in positive functional connectivity; <b>”↓-“</b>: decrease in negative functional connectivity; <b>”↑+“</b>: increase in positive connectivity; <b>”</b></p><p><b>↑-“</b>: increase in negative connectivity;”</p><p>The last two columns show the correlation coefficient and corresponding <i>p</i> value between the strength of functional connectivity and MMSE scores, and the results for a threshold of <b><i>p</i> < 0.05</b> are shown in bold.</p><p>Regions showing functional connectivity differences of the left/right thalamus between the EMCI and HC group (<i>P</i> < 0.01, 40 voxels, corrected for multiple comparisons).</p

Demographics and clinical information.

<p>Data are given as mean ± standard deviation (SD); MMSE, Mini-Mental State Examination; CDR, Clinical Dementia Rating</p><p>a: The <i>P</i> value was obtained by an independence Pearson chi-square test.</p><p>b: The <i>P</i> value was obtained by a one-way analysis of variance test.</p><p>Demographics and clinical information.</p