Medical decision-making in Alzheimer’s disease : a linguistic approach

Sammanfattning: Objectives. To explore medical decision-making capacity (MDC) for research participation, in patients with Alzheimer's disease, using a linguistic approach and including comparable groups. Materials and Methods. The thesis comprises five studies, based upon two separate data collections from three groups of elderly with varied cognitive function: Alzheimer’ disease (AD; dataset 1: n= 20 and dataset II: n=21), mild cognitive impairment (MCI; dataset 1: n= 22 and dataset II: n=17) and healthy controls (HC; dataset 1: n= 37 and dataset II: n=17). Studies I-III and V are primarily quantitative studies investigating medical decision-making in research as measured by two different linguistic instruments (LIMD and KIMB) and patients’ self-estimation by visual analogue scale (VAS), correlated to demographic factors and cognitive and linguistic abilities. Study IV is a qualitative study, analysing the sensemaking of selected utterances by conducting semantic analysis. Results. Study I: A Swedish Linguistic Instrument of Medical-Decision making (LIMD) was developed and demonstrated good psychometric features. Study II: Multiple factors are involved in MDC (assessed by LIMD) such as overall verbal knowledge, episodic memory, cognitive speed and working memory. LIMD total score showed highest correlation to the single test Reading Speed (which assesses both rapid reading, inference and understanding). Study III: AD patients showed high acceptance to participate in a high-risk trial as well as reduced capability to notify risk. Study IV: Irregularly placed, and sporadically used linguistic signs for time, place and person may lead to difficulties interpreting and understanding the meaning of verbal utterances. Study V: A brief Swedish reading tool (KIMB-t) was developed to detect patients with reduced capacity to give informed consent. Conclusions. The linguistic and cognitive functions associated with comprehending, evaluating and communicating a choice, may affect MDC, referred to as the capacity to make decisions in research settings e.g. to give informed consent. Patients, already with mild AD are likely to have reduced capacity to identify and estimate possible risks as well as difficulties in reasoning and to communicate a choice in a clear and logical manner. Evaluating different aspects associated to medical decision-making from a linguistic perspective, in groups with varied cognitive function, contributes to further knowledge in the field. The results indicate that a linguistic approach can contribute not only to further analysis of MDC, but also to a better understanding in the communication with patients with impaired cognitive function, during the decision-making process.