Neuropsychology of aging and dementia

Brain SPECT as a Biomarker of Neurodegeneration in Dementia in the Era of Molecular Imaging: Still a Valid Option?

Biomarkers are playing a progressively leading role in both clinical practice and scientific research in dementia. Although amyloid and tau biomarkers have gained ground in the clinical community in recent years, neurodegeneration biomarkers continue to play a key role due to their ability to identify different patterns of brain involvement that sign the transition between asymptomatic and symptomatic stages of the disease with high sensitivity and specificity. Both ¹⁸F-FDG positron emission tomography (PET) and perfusion single photon emission computed tomography (SPECT) have proved useful to reveal the functional alterations underlying various neurodegenerative diseases. Although the focus of nuclear neuroimaging has shifted to PET, the lower cost and wider availability of SPECT make it a still valid alternative for the study of patients with dementia. This review discusses the principles of both techniques, compares their diagnostic performance for the diagnosis of neurodegenerative diseases and highlights the role of SPECT to characterize patients from low- and middle-income countries, where special care of additional costs is particularly needed to meet the new recommendations for the diagnosis and characterization of patients with dementia.

Prevalence and psychosocial correlates of subjectively perceived decline in five cognitive domains: Results from a population-based cohort study in Germany

OBJECTIVE

Subjective cognitive decline (SCD) was frequently investigated for memory in healthy aging or in relation to diseases like dementia. It was found to be related to sociodemographic and psychological variables as well as cognitive abilities. The prevalence of SCD in other cognitive domains and their relation to these variables is largely unknown to date. The present study aimed to fill this gap.

METHODS

A total of 807 subjects (18-85 years of age, M = 57.8 years, female: 43%) completed the Juelich Questionnaire on Subjective Cognitive Decline, to investigate SCD in memory, attention, language, motor, and executive functions. Logistic regression analyses were used to estimate association of depressive symptomatology, emotionality, and general cognitive performance as well as age, gender, and educational attainment with domain-specific SCD.

RESULTS

The highest prevalence rate was obtained for the memory domain (65.9%), followed by the attention (54.6%), motor (52.9%), executive (39.7%), and language domain (31.5%). Of the psychosocial factors, only age, depressive symptomatology and emotionality were consistently and strongly associated with domain-specific SCD prevalence.

CONCLUSIONS

SCD is prevalent not only in the memory domain, but also in other major cognitive domains. Our results also suggest that the suspicion from previous research, that subjective memory decline might be more strongly associated with depressive symptomatology and emotionality than with actual decline of cognitive performance, might also apply to the attention, motor, executive, and language domain. Further investigations using neuropsychological testing for specific cognitive functions and employing longitudinal designs are required for substantiating this suspicion.

The Role of Neuropsychology in the Assessment of the Cognitively Impaired Elderly

Cognitive abilities decline with age and older adults, as a group, are at increased risk for developing age-related cognitive disorders. Neuropsychological evaluation provides objective quantification of the type and severity of cognitive deficits that can affect the elderly population and elucidates a pattern of scores that provides diagnostic clues regarding etiology. It can also detect mild cognitive impairment that may not be evident on bedside assessment or mental status examination and provides critical information regarding the progression of cognitive changes through serial evaluations. Such information assists in counseling patients and family members and can guide therapeutic decisions.

The episodic memory system: neurocircuitry and disorders

The ability to encode and retrieve our daily personal experiences, called episodic memory, is supported by the circuitry of the medial temporal lobe (MTL), including the hippocampus, which interacts extensively with a number of specific distributed cortical and subcortical structures. In both animals and humans, evidence from anatomical, neuropsychological, and physiological studies indicates that cortical components of this system have key functions in several aspects of perception and cognition, whereas the MTL structures mediate the organization and persistence of the network of memories whose details are stored in those cortical areas. Structures within the MTL, and particularly the hippocampus, have distinct functions in combining information from multiple cortical streams, supporting our ability to encode and retrieve details of events that compose episodic memories. Conversely, selective damage in the hippocampus, MTL, and other structures of the large-scale memory system, or deterioration of these areas in several diseases and disorders, compromises episodic memory. A growing body of evidence is converging on a functional organization of the cortical, subcortical, and MTL structures that support the fundamental features of episodic memory in humans and animals.