Chronic obstructive pulmonary disease as a risk factor for dementia

Cognitive function in COPD 2 ARC Publishing Introduction Chronic obstructive pulmonary disease (COPD) is a disease of the respiratory system, which is characterized by a persistent blockage of airflow from the lungs. This is an under-diagnosed, life-threatening pulmonary pathology that interferes with normal breathing and is completely incurable. According to the World Health Organization (WHO) (January 2015) the most famous terms 'chronic bronchitis' and 'emphysema' are no longer used; they are now included within the COPD diagnosis [1]. COPD is a major public health problem. According to data released by the World Bank and the WHO, it is estimated that in 2020 it will be on the 5th place on the damage caused by disease globally [2]. COPD is the fourth most common cause of death in the world [3] and represents a serious threat to public health, leading to very significant economic and social burden, and its impact is increasing [4, 5]. In addition, although in recent years COPD attracted more and more attention from the medical community, this disease is relatively unknown or given little importance by the general public, as well as official representatives of health authorities and government agencies [2]. This lack of awarness is reflected by the fact that timely diagnosis occurs only in 25% of cases [6]. At the same time, the number of patients with COPD is increasing every year due to unfavorable environmental conditions, including the high prevalence of smoking. A particularly high figure in developing countries. Currently in North America, 10% of persons over 55 years has been diagnosed with COPD. In the European Union, COPD has been established as an independent factor leading to early disability of patients and reducing natural life expectancy by an average of 8 years. The death rate among patient with COPD ranges from 2.3 to 41.4 per 100,000 [6-9]. COPD is now considered as a systemic disease in which multiple complications occur and with primary changes in body structures with the highest level of metabolic processes, such as the central nervous system. The main mechanism of cognitive impairment in patients with COPD is damaged neuronal structures. Cognitive function is the most complex function of the brain and includes: the perception of information, processing and analysis of information, memorization and storage of information, the exchange of information, construction and implementation of the program of action. Pulmonary pathology leads to disruption of cerebral blood flow [10, 11]. The expression of vascular disorders increases as the disease progresses. In the development of cognitive deficits in patients with COPD circulatory disturbances in cerebral basin have an important role [12]. On the other hand, when there is bronchial obstruction we can see the chronic hypoxia of the brain, which also has a negative impact on higher mental functions such as memory, attention, thinking. The main damaging factors include hypoxia, hypercapnia, acidosis and hypoxia associated with hyperventilation [13,14]. Abnormal cognitive function was discovered in patients with COPD, even in mild stage I-II disease processes [15]. The studying of cognitive impairment and oxygen saturation of hemoglobin in patients with hypertension combined with COPD raises interest since it shows the dominant role of hypoxia as a major development mechanism of systemic arterial hypertension in patients with COPD [16]. The risk of not amnestic cognitive functions grows by 83% against the background of COPD, while there is an opinion, that the violation of gas exchange and oxygen deficiency in the body at that process affects to the brain’s condition. Many patients with COPD suffer from sleep disorders, which also affects the cognitive functions [17]. There were found structural changes in the white matter of the brain using magnetic resonance imaging in patients with COPD [18]. The stage II of the disease is characterized by: moderately for COPD; the ratio of forced expiratory volume (FEV) / forced vital capacity (FVC) <70%. This is the stage at which patients seek medical attention because of dyspnea or worsening of the disease. There is an increase in obstructive disorders (50% <FEV1 <70% of predicted values), as well as growing disease and shortness of breath symptoms appearing during physical exertion. The stage III of the disease is characterized by: severe COPD; FEV / FVC <70%. There is a further increase in airflow limitation (30% <FEV, <50% of predicted value), increase of breathlessness, and frequent exacerbations. The stage IV of the disease is characterized by: very severe COPD; FEV / FVC <70%. At this stage, quality of life deteriorates markedly, and exacerbation can be life-threatening. There is extremely severe airflow obstruction (FEV <30% of predicted values or FEV <50% of predicted values in the presence of respiratory failure). At this stage the possible development of pulmonary heart disease. In recent years, research highlights the importance of the quality of life parameter caused by many components, including the severity of cognitive disorders. COPD is a systemic disease with a variety of extrapulmonary manifestations, among which, according to recent studies, an important role belongs to cognitive impairment. Cognitive dysfunction is found in 77% of patients with hypoxemic COPD and is associated with high mortality and disability [19]. These disorders are linked with one of the worse prognosis in patients with COPD. The problem of cognitive impairment and dementia is not only medical but also social, since it further affects the quality of life of patients and results in large economic losses. However, despite the importance of this issue, the understanding of the processes associated with cognitive deficits in COPD and causing it remains incomplete [20]. Despite the fact that the problem of cognitive impairment in patients with COPD has a long history, to date there is no single clear understanding of its 3 Turuspekova et al. International Journal of Clinical Neurosciences and Mental Health 2016; 3(Suppl. 1):S04 many aspects, and not all authors acknowledge the existence of cognitive disorders in patients with COPD [21]. This study aims to assess the state of cognitive functions in patients with COPD.