Brain imaging to be on track for improving diagnosis and pathophysiological insights in neuropsychiatric diseases

Abstract

Brain imaging techniques are becoming increasingly important in diagnosis and course of neuropsychiatric diseases. This is best demonstrated in dementia, where besides the volumetric investigation of the hippocampus, single-photon emission-computed tomography (SPECT) revealed hyperperfusion patterns in its several subtypes. International guidelines have suggested SPECT to be useful in differentiating several forms of dementia such as Alzheimer’s disease, vascular dementia, frontotemporal dementia and dementia with Lewy bodies. In a metaanalysis and review, Yeo et al. [1] calculated sensitivity and specifity of Tc-HMPAO-SPECT in distinguishing dementia subtypes. They found SPECT investigations of diagnostic value, particularly in differentiating Alzheimer’s dementia from frontotemporal dementia and healthy controls, adding information to the clinical test results. In addition, cerebrospinal fluid (CSF) markers are recommended for dementia diagnosis. Guo et al. [2] investigated protein expression in healthy controls, patients with mild cognitive impairment (MCI) and Alzheimer’s dementia and found heart-type fatty acid-binding protein and vascular endothelial growth factor in CSF to distinguish between patients with Alzheimer’s dementia and healthy controls with lower sensitivity and higher specificity and to predict the progression of MCI to dementia. They recommend combining these markers with the three established markers Amyloid-s1-42, total-Tau and phosphorylatedTau, increasing sensitivity to 83 % and specifity to 86 %. Adults with attention-deficit hyperactivity disorder (ADHD) consistently have been reported to exhibit working memory deficits, contributing to inattentive behavior and hyperactivity. Using a functional magnetic resonance imaging (fMRI) paradigm, Ko et al. [3] demonstrated that during a two-back working memory task, indeed both the adults with ADHD and healthy controls activate the frontoparietal network but ADHD patients to reveal higher brain activity over the bilateral anterior cingulate cortex, left inferior frontal lobe, hippocampus and supplementary motor area. Increasing the task loading to 3-back task, the control group showed increased brain activation, while the ADHD group exhibited greater decrease in brain activation over the left fronto-parietal network, suggesting impaired fronto-parietal network when demands of working memory exceed the capacity of patients with ADHD. Post-traumatic stress disorder (PTSD) includes key symptoms as anxiety, hyperarousal, dissociative disturbances and a restricted range of emotions, called emotional numbing. To identify neuronal circuitry involved in emotional dysfunction, Mazza et al. [4] via fMRI investigated subjects with PTSD while presenting pictures with negative emotional valence versus neutral stimuli. Compared to healthy controls, PTSD patients showed hyperactivation in the left posterior insula, exerting influence on subcortical brain regions. These alterations may underly the emotional, social and relational difficulties in PTSD. Being an important interface between emotion and cognition, the anterior cingulate cortex (ACC) is strongly connected to the amygdala and involved in fear response regulation. In a structural MRI study, Jatzko et al. [5] delineated the ACC in 15 PTSD victims. While detecting no differences in absolute ACC volumes between patients and controls, they found one pattern, namely the single segmented cingulate sulcus, to be predominant in PTSD subjects. Further A. Schmitt (&) P. Falkai Department of Psychiatry and Psychotherapy, LudwigMaximilians-University Munich, Nusbaumstr. 7, 80336 Munich, Germany e-mail: Andrea.Schmitt@med.uni-muenchen.de