Cognitive function in elderly patients with chronic heart failure

Abstract: IntroductionApproximately 1-2% of the adult population in developed countries suffer from heart failure (HF), with the prevalence rising to more than 10% among patients 80 years of age or older. The HF syndrome is associated with elevated mortality and morbidity, and decreased quality of life. Cognitive dysfunction has been reported in patients suffering from a variety of cardiovascular disorders. However, few studies have systematically assessed cognitive performance in HF patients, its prevalence and other factors influencing cognition in HF patients. Further, it is of great interest to understand the relationship between self-care in HF and cognition. It may be important to screen for cognitive dysfunction as it may influence HF patients’ ability to perform self-care, e.g. make lifestyle changes, adhere to medical treatment and monitor, evaluate and treat symptoms of deterioration.AimThe overall aim of this thesis was to explore cognitive function in elderly patients with chronic heart failure with focus on prevalence, risk factors, sleep and self-care.Design and methodThis thesis is based on four quantitative studies. The data from study I and II were collected in a prospective longitudinal design, including Swedish same-sex twin pairs born in 1913 or earlier in Sweden. The study was conducted 1991-2002 and a total of 702 individuals aged 80 and older were included.Study III and IV had a cross- sectional design and included stable HF patients, median 72 years of age, living in the community in the south of Sweden. Data were collected between 2009 and 2012. Study III included a total of 137 patients and Study IV included 142 patients.ResultsStudy I found that  octogenarians with HF had significantly poorer spatial performance and episodic memory, and that the episodic memory declined more over time compared to a non-HF population of the same ages.Study II showed that octogenarians with HF had a significantly higher prevalence of vascular dementia, 16% vs. 6%, and all types of dementia, 40% vs. 30%, than those not diagnosed with HF. Factors related to dementia in individuals with HF were depression, hypertension and increased levels of homocysteine. Diabetes was associated with an increased risk for vascular dementia.In study III we found that  HF patients with sleep disordered breathing (SDB) (apnoea-hypopnoea index >15) had significantly higher saturation time < 90%, more difficulties maintaining sleep and lower levels of daytime sleepiness compared to those in the non-SDB group. Cognitive function did not differ between the SDB and the non-SDB-group. Only insomnia was associated with a decreased global cognititive function measured with the Mini Mental State Examination instrument.Finally, in study IV, the relationship between self-care and different dimensions of cognitive function was explored. Psycho- and visuomotor function (speed and attention) was the only dimension of cognitive function associated with self-care.ConclusionOctogenarians suffering from HF have a decreased performance in spatial and episodic memory and they also have a higher risk for developing dementia. Cognitive dysfunction as well as higher prevalence of dementia can contribute to decreased adherence to prescribed therapy and self-care management, and lead to other socio-behavioural problems.  Self-care was found to be associated with psychomotor speed. This may influence sustained attention negatively and the ability to carry out more than one task at the same time. This may lead to decreased attention for receiving and understanding information on self-care.