Posterior cortical atrophy: an exemplar for renovating diagnostic formulation in neuropsychiatry

Visuospatial working memory dysfunction from tapping span test as a diagnostic tool for patients with mild posterior cortical atrophy

Posterior cortical atrophy is a rare degenerative condition with prominent visuospatial dysfunction which commonly occurs between ages 50 and 65. A diagnosis of mild posterior cortical atrophy sometimes challenging and can be delayed because there are currently no established neuropsychological examination methods that can easily be used in clinical settings. In this study, we examined whether the tapping span test is a potential diagnostic tool for posterior cortical atrophy and what impairment the tapping span test is indicative of in this condition. Eight patients with mild posterior cortical atrophy were recruited. Age- and severity-matched individuals with amnesic Alzheimer's disease (n = 9) were also recruited as a control group. The participants were subjected to the tapping span test and several visuospatial working memory tests. The results of the tapping span and visuospatial working memory tests were worse for the posterior cortical atrophy group when compared with the control group. The results from the tapping span tests were strongly correlated with those from the visuospatial working memory tests. The tapping span test is a simple and potentially useful diagnostic tool for patients with mild posterior cortical atrophy, as it reflects visuospatial working memory function.

Neuroimaging Education in Psychiatry Residency Training: Needs Assessment

OBJECTIVE

The authors investigated the attitudes, self-perceived knowledge, and the need for a dedicated neuroimaging curriculum among psychiatrists-in-training.

METHODS

An anonymous voluntary 20-item Web-based survey was distributed to psychiatry residents at seven university-based USA programs between December 2017 and February 2019.

RESULTS

Of 302 psychiatry residents, 183 (response rate, 60.5%) completed the survey. Although a large majority of residents (83%) believed that neuroradiology education is important to psychiatric training, only 7% reported that they are receiving adequate training in this discipline. The majority (80%) believed that there should be a formal neuroimaging curriculum during their training. Self-perceived competence and comfort level was found to be low with several psychiatrically relevant neuroimaging modalities. In particular, regarding CT head/brain MRI, there was a marked difference in self-perceived competence at interpreting the actual brain images (8%) versus the radiological reports/impression summaries (48%). Comfort level with functional neuroimaging was especially low (7%). Clinically, only 26% reported confidence at being able to explain neuroimaging topics to patients. Compared to junior residents, senior residents rated higher confidence at interpreting the radiological reports/impression summaries of CT head/brain MRI (p = 0.008) and PET/SPECT (p = 0.014), but no difference was found with the actual brain images. Further, senior residents were less likely to identify with "neurophobia" (p = 0.028) and more likely to believe that a neuroimaging curriculum should be included in psychiatric residency training (p = 0.027) when compared to junior residents.

CONCLUSIONS

Psychiatrists-in-training have a very strong interest in neuroimaging education. Future educational interventions should address this need.

Difficulty differentiating a case of posterior cortical atrophy from a psychogenic disturbance of vision

Differentiating posterior cortical atrophy (PCA) from other diseases can be difficult and time-consuming, and there is a particularly high possibility of misdiagnosis when psychiatrists diagnose complaints related to visual perception. Here, a case of PCA involving prominent visual perceptual disorders is reported; PCA was difficult to distinguish from psychogenic disturbance of vision in this case. For a year, a 59-year-old woman had had visual perceptual disorders, including a distorted view and prosopagnosia. She underwent examinations at multiple clinical departments at several medical institutions before receiving a definitive diagnosis of PCA. This PCA diagnosis was based on clinical symptoms, including Gerstmann syndrome, Bálint's syndrome, and transcortical sensory aphasia, and hypoperfusion in the occipital lobe observed on single-photon emission computed tomography. This case was initially misdiagnosed as a psychogenic disease partly because characteristic clinical manifestations of PCA include visual agnosia with a disjunctive component. This patient displayed a disordered perception of stationary objects but an intact perception of moving objects. For example, she had to grope her way through a room at home, but she could visit a familiar hair salon on foot without hindrance. Behaviours like claiming to be blind while inexplicably moving without colliding with surrounding objects may lead to the misdiagnosis of PCA as a psychogenic or dissociative disorder involving histrionic or neurologically irrational symptoms with an expectation of sympathy or personal gain. It is critical to make every effort to exclude organic diseases, even in cases provisionally diagnosed as psychogenic disease. Despite its low prevalence, PCA should be considered a syndrome caused by Alzheimer's disease, dementia with Lewy bodies, or other dementias.

A patient with posterior cortical atrophy possesses a novel mutation in the presenilin 1 gene

Posterior cortical atrophy is a dementia syndrome with symptoms of cortical visual dysfunction, associated with amyloid plaques and neurofibrillary tangles predominantly affecting visual association cortex. Most patients diagnosed with posterior cortical atrophy will finally develop a typical Alzheimer's disease. However, there are a variety of neuropathological processes, which could lead towards a clinical presentation of posterior cortical atrophy. Mutations in the presenilin 1 gene, affecting the function of γ-secretase, are the most common genetic cause of familial, early-onset Alzheimer's disease. Here we present a patient with a clinical diagnosis of posterior cortical atrophy who harbors a novel Presenilin 1 mutation (I211M). In silico analysis predicts that the mutation could influence the interaction between presenilin 1 and presenilin1 enhancer-2 protein, a protein partner within the γ-secretase complex. These findings along with published literature support the inclusion of posterior cortical atrophy on the Alzheimer's disease spectrum.