Investigating the Factor Structure of the Preclinical Alzheimer Cognitive Composite and Cognitive Function Index across Racial/Ethnic, Sex, and Aß Status Groups in the A4 Study.

BACKGROUND: Disparities in Alzheimer's disease (AD) are well-documented among different racial/ethnic groups and between sex/genders. Neuropsychological assessment provides important information about cognitive changes and can offer valuable insights into disparities. However, neuropsychological measures must be comparable across racial/ethnic and sex/gender groups to accurately interpret disparities. OBJECTIVES: To evaluate measurement invariance (equivalence) of the Preclinical Alzheimer Cognitive Composite (PACC) and the Cognitive Function Index across racial/ethnic, sex/gender, and ß-amyloid (Aß) status groups. DESIGN, SETTING, PARTICIPANTS: Cross-sectional analysis of screening data from the Anti-Amyloid in Asymptomatic AD (A4) Study. The study enrolled participants aged 65-85 from sites across the United States, Canada, Australia, and Japan. MEASUREMENTS: Participants completed the PACC and the Cognitive Function Index. Participants classified as cognitively normal also underwent a Positron Emission Tomography (PET) scan to determine Aß status. RESULTS: Participants self-identified as non-Hispanic White (n=5241), non-Hispanic Black (n=267), Asian (n=228), or Hispanic White (n=225) as well as male (n=2885) or female (n=3076). Among those who underwent a PET scan, 3115 were classified as Aß- and 1309 were classified as Aß+. We found support for a one-factor model for both the PACC and Cognitive Function Index across the full sample and in samples stratified by race/ethnicity, sex/gender, and Aß status. The one-factor model of the PACC and Cognitive Function Index demonstrated scalar measurement invariance across racial/ethnic, sex/gender, and Aß status groups. CONCLUSIONS: Our findings suggest that performance on the PACC and Cognitive Function Index can be compared across the racial/ethnic, sex/gender, and Aß status groups examined in this study.

Is it time to revise the diagnostic criteria for apathy in brain disorders? The 2018 international consensus group.

BACKGROUND: Apathy is a very common behavioural and psychological symptom across brain disorders. In the last decade, there have been considerable advances in research on apathy and motivation. It is thus important to revise the apathy diagnostic criteria published in 2009. The main objectives were to: a) revise the definition of apathy; b) update the list of apathy dimensions; c) operationalise the diagnostic criteria; and d) suggest appropriate assessment tools including new technologies. METHODS: The expert panel (N = 23) included researchers and health care professionals working on brain disorders and apathy, a representative of a regulatory body, and a representative of the pharmaceutical industry. The revised diagnostic criteria for apathy were developed in a two-step process. First, following the standard Delphi methodology, the experts were asked to answer questions via web-survey in two rounds. Second, all the collected information was discussed on the occasion of the 26th European Congress of Psychiatry held in Nice (France). RESULTS: Apathy was defined as a quantitative reduction of goal-directed activity in comparison to the patient's previous level of functioning (criterion A). Symptoms must persist for at least four weeks, and affect at least two of the three apathy dimensions (behaviour/cognition; emotion; social interaction; criterion B). Apathy should cause identifiable functional impairments (criterion C), and should not be fully explained by other factors, such as effects of a substance or major changes in the patient's environment (Criterion D). CONCLUSIONS: The new diagnostic criteria for apathy provide a clinical and scientific framework to increase the validity of apathy as a clinical construct. This should also help to pave the path for apathy in brain disorders to be an interventional target.