Delirium, also known as acute confusional state, organic brain syndrome, brain failure, and encephalopathy, is a common occurrence among medical and surgical patients and causes extensive morbidity and mortality. This chapter provides an updated review of delirium, including pathophysiological correlates, clinical features, diagnostic considerations, and contemporary treatment options. The defining features of delirium include an acute change in mental status characterized by altered consciousness, cognition, and fluctuations. The chapter explores the risk factors for delirium. These can be divided into two categories: predisposing factors and precipitating factors. Imbalances in the synthesis, release, and degradation in gamma-aminobutyric acid (GABA), glutamate, acetylcholine, and the monoamines have also been hypothesized to have roles in delirium. GABA is the primary inhibitory neurotransmitter in the central nervous system (CNS) and medications such as benzodiazepines and propofol have known actions at GABA receptors and have been associated with delirium.

Primary progressive aphasia (PPA) is the term applied to a clinical syndrome characterized by insidious progressive language impairment that is initially unaccompanied by other cognitive deficits. This chapter describes several variants of PPA and more than one etiology. It explains three main variants of PPA, namely, semantic Variant of PPA (svPPA), nonfluent/agrammatic variant of PPA (nfvPPA) and logopenic variant of PPA (lvPPA), and also describes criteria for their diagnoses. The defining symptom of PPA is the presence of a language impairment for at least 2 years in the absence of any other significant cognitive problem. Assessment of other cognitive domains is challenging because many tests of memory, attention, executive functioning, and visual-spatial skills rely on language processes in some manner. There are no drug therapies proven to arrest progression of signs and symptoms of PPA due to frontotemporal lobar dementia (FTLD) or Alzheimer’s disease (AD) pathologies.

Dementia is an umbrella term for conditions such as Alzheimer’s disease (AD), dementia with Lewy bodies (DLB), vascular dementia (VaD), and frontotemporal dementia (FTD). Under that umbrella, FTD, also known as frontotemporal lobar degeneration (FTLD), can be further categorized to define a group of neurodegenerative disorders resulting from a progressive deterioration of the cells in the anterior temporal and/or frontal lobes of the brain. More specifically, ventromedial-frontopolar cortex is identified with metabolic impairment in FTD. This chapter elaborates on the history, epidemiology, pathophysiology, clinical features, treatment, and outcomes of FTD. The history and background section of each of the FTD categories highlights the evolution of the disease conceptualization. The FTD subtypes are conceptualized in three categories: neurobehavioral variant, motor variant, and language variant. The chapter illustrates the features of all three categories of FTD.

The concept of Mild cognitive impairment (MCI) makes a lot of sense in that individuals are typically not “normal” one day and “demented” the next. In theory, especially for progressive neurodegenerative conditions, such as Alzheimer’s disease (AD), frontotemporal dementia (FTD), the development of dementia may take months or years. The clinical syndrome of MCI due to AD can be identified via a neuropsychological evaluation or less-sensitive cognitive screening measures. Much of what we are learning about MCI, and therefore refining its diagnostic criteria, is coming from two large-scale studies of cognition and aging: Alzheimer’s Disease Neuroimaging Initiative (ADNI) and Australian Imaging, Biomarkers and Lifestyle (AIBL). According to the most recent research diagnostic criteria for MCI due to AD, evidence of beta-amyloid deposition, neuronal injury, and/or other biochemical changes needs to be seen to increase confidence of the etiology of MCI. Cholinesterase inhibitors remain the primary pharmacological treatment for AD.

This chapter suggests that the dysexecutive syndrome associated with vascular dementia (VaD) is caused by impairment in separate but related cognitive concepts; that is, pathological inertia, mental bradyphrenia, disengagement, and temporal reordering. During the late 19th and early 20th centuries, cerebrovascular dementia was a well-established clinical syndrome. Multi-infarct dementia (MID) generally became associated with all types of vascular syndromes. Recent research suggests the presence of considerable overlap between the neuropathology underlying Alzheimer’s disease (AD) and VaD. Patients diagnosed with VaD tend to produce hyperkinetic/interminable perseverations, suggesting an inability to appropriately terminate a motor response. Other aspects of the dysexecutive syndrome associated with VaD revolve around constructs related to interference inhibition, flexibility of response selection, and sustained attention. From the view point of diagnosis, the neuropathology of VaD often differentially impacts the frontal lobes, whereas the neuropathology associated with AD revolves more around circumscribed temporal lobe involvement.

Dementia pugilistica (DP) is a form of chronic traumatic encephalopathy (CTE) that involves gross impairment of cognitive and motor functioning due to repetitive blows to the head from boxing. Rapidly increasing in popularity among fight fans and fighters is mixed martial arts (MMA). In the area of sport-related concussion, there are two other frequently used terms that are necessary to distinguish from DP and CTE: postconcussion syndrome (PCS) and second impact syndrome (SIS). The classical clinical signs and symptoms of DP include combinations of dysarthria, incoordination, gait disturbance, pyramidal and extrapyramidal dysfunction, and cognitive impairment. Some media reports about concussion and the potential link between repetitive concussions and long-term problems include eye-catching and emotionally provocative titles. This chapter has provided an overview of the many complex issues surrounding the effects of repeat concussive trauma, particularly in sports.

The Transmissible spongiform encephalopathies (TSEs) form a group of illnesses, characterized by a pathological form of the native prion protein, which results in a rapidly progressive neurodegenerative illness. They also are responsible for Gerstmann-Strâussler-Scheinker (GSS) syndrome and fatal familial insomnia (FFI), and they have been produced experimentally in several other animals. Creutzfeldt-Jakob disease (CJD) is the most common TSE in humans. Human prion diseases have three etiologies: (a) sporadic, (b) genetic, and (c) acquired. Human prion diseases are important to understand because of their underlying pathophysiology, public health implications, and clinical features that often result in misdiagnosis. This chapter reviews the historical discovery of prion diseases and the formulation of the prion hypothesis. It explores prion hypothesis and the neuropathogenesis of prion diseases. The chapter ends with a description of the diagnosis, prognosis, and experimental treatment of human prion diseases.

Dementia with Lewy bodies (DLB) is a clinical syndrome characterized by progressive dementia, cognitive fluctuations, visual hallucinations (VH), and parkinsonism. In 1961, Okazaki, Lipkin, and Aronson reported two patients with dementia and parkinsonism with cortical neuronal inclusions similar to the brain-stem Lewy bodies (LB) seen in Parkinson’s disease (PD). LBs are intra-cytoplasmic neuronal inclusions containing α-synuclein and ubiquitin. There are other associated pathological features in DLB such as spongiform change neuronal loss, and Alzheimer’s disease (AD) pathology includes amyloid plaques and neurofibrillary tangles (NFTs). DLB and other entities such as PD and multiple system atrophy (MSA) have been grouped under the term synucleinopathies due to the existence of &#945-synuclein inclusions in the brain. The central feature required for a diagnosis of DLB is the presence of dementia: a progressive cognitive decline of sufficient magnitude to interfere with normal social or occupational function.

This chapter describes an overview of the procedures that a neuropsychologist may apply to a range of similar referrals in the area of civil capacities. It explores the presentation of a framework developed by the American Bar Association/American Psychological Association (ABA/APA) working group on capacity issues and provides more specific guidance regarding assessment tools. Decision making is a complex cognitive process that involves multiple brain regions and brain systems. Injuries to the prefrontal cortex are common in dementia and are often linked to changes in decision-making abilities. Key differences between clinical assessments and those for capacity evaluations include knowledge of relevant legal and ethical issues, a functional assessment, and an ability to present neuropsychological data to lay readers. Research on medical consent capacity and financial capacity highlight the importance of the assessment of calculation, executive function, and verbal memory as part of any test battery.

Chronic alcohol use has been related to various linked disorders when used in excess, particularly when this excessive use becomes chronic. It is important for clinicians to clarify the amount and type of alcohol being consumed and the frequency of this consumption when considering its potential role in any neuropsychological profile. The most commonly reported terms found in the literature include alcohol-induced persisting dementia (APA), alcohol-related dementia, and Korsakoff’s syndrome (KS). This chapter provides some synthesis of this literature to offer some clarity on cognitive dysfunction as it relates to alcohol and the manifestation of dementia as a result of chronic use, including discussion of the classic KS and related presentations. Alcohol dependency is commonly associated with a number of neurological impairments including deficits in abstract problem solving, visuospatial and verbal learning, memory function, perceptual-motor skills, and even motor function.