We discussed "what is common and what is different" between the patients with anarthrie/ apraxia of speech due to cerebrovascular and neurodegenerative diseases based on the previous report. The common point was the broad correspondence between localization of brain lesions and prominent speech characteristics. The different point was that patients with neurodegenerative diseases showed two speech characteristics distinguishable from patients with cerebrovascular diseases. First, they exhibited prominent distorted articulation and lengthened morae compared with the segmented morae. Second, they could not always complete the production of single words in one breath. We suspected that anarthrie/apraxia of speech due to neurodegenerative diseases had selective damage to the neural networks for speech including respiratory and phonatory coordination. We conclude that the different pathological mechanisms may be responsible for the difference in speech symptoms between cerebrovascular and neurodegenerative diseases.
Cognitive impairments after traumatic brain injury is considered to be resulted from both focal brain injury due to brain contusion and diffuse axonal injury. Symptoms caused by brain contusion are similar to those with focal brain injury, such as cerebrovascular diseases, which depend on the individual lesion area. In contrast, cognitive dysfunctions after diffuse axonal injury is not confined to one domain, rather, they include a wide range of cognitive functions, e.g., attention, executive function, proceeding speed, and working memory, as well as behavioral and psychiatric symptoms, such as apathy, preoccupation, and emotional instability. From clinical observation, there is a possibility that preoccupation and emotional instability might be related to deficits in processing speed and working memory.
In the early stage of dementia with Lewy bodies (DLB), 20% of patients have misidentifications (misidentifications of person, misidentification of place, "deceased/absent relatives are in the house", TV sign). In Alzheimer disease (AD), misidentifications are rare in the early stage, but often found in the advanced stage. Details of the misidentifications are similar between AD and DLB, but an ambiguous misidentification of person such as "I don't know who he/she is" is popular in AD.
Persecutory delusions are the most popular among delusions in dementia and found in 40% of AD, including delusion of theft, abandoned, and jealousy. 25% of the DLB patients also have persecutory delusions the details of which are similar to those in AD. Psychosocial factors often influence the details or target of persecutory delusions in AD. In addition, visual hallucinations or misidentifications of person can affect the details of persecutory delusions in DLB. DLB patients have delusion of jealousy more frequently than AD patients, because visual hallucinations and misidentifications of person in DLB patients can induce delusion of jealousy secondarily.
Semantic dementia (SD) is a subtype of frontotemporal dementia characterized by progressive loss of semantic memory and behavioral change due to focal atrophy in the temporal lobe. Autism spectrum disorder (ASD) is a neurodevelopmental disorder diagnosed when the characteristic deficits of social communication are accompanied by excessively repetitive behaviors, restricted interests, and insistence of sameness. In this article we discussed symptomatic similarities between SD and ASD, which have quite different pathological backgrounds. First, we evaluated whether SD has autistic traits by using pervasive developmental disorders Autism Society Japan Rating Scale (PARS) and found that the PARS score of SD patients were so high that they could be diagnosed as ASD. Thus, Patients who develop SD can exhibit traits of ASD. Next, we noticed that both SD and ASD have unique cognitive style that focus in detail and hard to understanding the whole image. In patients with traumatic brain injury or neurodegenerative disease, such a cognitive style has been referred to as "impairment of abstract attitude". Interestingly, there is a similar theory to explain the characteristic deficits of social communication and cognitive style of ASD, which is called the weak central coherence theory. We evaluated the deficits of cognitive processing in SD from the viewpoint of abstract attitude and weak central coherence and showed that abstract attitude was commonly impaired in SD patients. We argued that the impairment of abstract attitude may lead some social impairment and behavioral disorder characterized in SD.