Hamid R. Sohrabi

This chapter discusses some of the neurocognitive deficits experienced in the Alzheimer's disease (AD) conditions, with the primary focus on different stages of dementia due to AD. It discusses the cognitive functions affected during the natural course of AD and other neurodegenerative diseases. The chapter discusses the most common neurocognitive features of AD as well as other common types of dementias. Attention and working memory deficits are commonly seen in AD patients. Following the amnestic phase of AD, attention is the second cognitive function to be affected, long before difficulties with other cognitive functions including language and praxis. There is a gradual major shift in cognitive and clinical examination, using online and computerised measures. The traditional neuropsychological approach of 'in‐person' testing should adapt and make use of such an unprecedented approach that can bring big‐data available for clinical practice, establishing psychometric basis of the available measures, and providing an avenue to develop new measures.

Neurodegenerative diseases are a heterogeneous group of disorders or conditions characterised by the progressive degeneration of the structure and function of the central nervous system or the peripheral nervous system. Some are considered to be caused by protein misfolding, some involve disruptions to intracellular processes such as mitochondrial function or protein degradation pathways, and some are genetic in origin. Whatever the original cause of the disease, the greatest risk factor for most of these diseases is increasing age. This book is mostly focused on Alzheimer's disease (AD), yet in this chapter we describe Alzheimer's as well as other major neurodegenerative conditions to demonstrate both similarities and differences.

Although Alzheimer's disease (AD) is the most common cause of dementia in the elderly, a definite diagnosis of AD normally requires post‐mortem examination. Without specialised brain scans and other tests that are currently only used for clinical research purposes, the many diagnostic tests that are presently available only result in a diagnosis of ‘probable’ AD. These diagnostic tests are also very time‐consuming. This chapter briefly describes the classical post‐mortem findings in an AD brain, then discusses the wide variety of current neuropsychological tests, followed by current and developing imaging and biomarker‐based clinical diagnostic methods.