Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 379

Common medical conditions in the elderly, such as gastrointestinal disease, malabsorption syndromes, acute and chronic infection, and hyper‐metabolism (i.e. hyperthyroidism), often cause anorexia, micronutrient deficiencies, and increased energy requirements. Cancer and rheumatoid arthritis, which produce anorectic effects by releasing cytokines, are also common in older adults. Protein‐energy malnutrition is particularly likely to develop in the presence of other ‘pathological’ factors, many of which become more common with increased age. The majority are at least partly responsive to treatment, so recognition is important.

Depression, often associated with bereavement and the deterioration of social networks, is a common psychological problem in older people, present in 2–10% of community‐dwelling older people and a much greater proportion of those in institutions. Depression is more likely to manifest as reduced appetite and weight loss in the elderly than in younger adults and is an important cause of weight loss and undernutrition in this group. Undernutrition per se, particularly if it produces folate deficiency, may further worsen depression, thus setting up a vicious cycle. Treatment of depression is effective in producing weight gain and improving other nutritional indices.

Dementia may also contribute to reduced food intake in the elderly, with a nearly twofold increased risk of anorexia compared with non‐demented subjects,⁶⁹ because individuals simply forget to eat. Up to 50% of institutionalized dementia patients have been reported to suffer from protein‐energy malnutrition.²⁷ Behavioral and psychological symptoms of dementia (BPSD) include eating problems. Apraxia of swallowing, including pocketing and spitting, delayed swallowing, and recurrent aspiration are associated with disease progression. Reduction of taste and smell may play a significant role. Weight loss is present very early, and even precedes dementia, and may be a significant preclinical marker.⁷⁰

Chronic diseases including chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), and chronic kidney disease (CKD) are associated with reduced appetite. Older adults with COPD are in a catabolic state due to increased whole‐body energy expenditure, and caloric intake was found to be inadequate for measured energy expenditure, which widens during severe acute exacerbations. Anorexia in COPD is also associated with nicotine use, opioid use for pain leading to early satiety, and gastrointestinal motility disorders.⁷¹

Loss of appetite occurs in over 40% of adults with end‐stage CHF.⁷² Generalized loss of lean, fat, and bone tissue occur. Cachetic CHF patients have raised plasma levels of norepinephrine, epinephrine, and cortisol, and they show high plasma renin activity and increased plasma aldosterone levels. Hypoxia may be the stimulus for increased TNF‐a production in CHF patients.⁷³ TNF has a variety of effects, including induction of apoptosis, rearrangement of the cytoskeleton leading to increased permeability to albumin and water, leading to impairment of the endothelial function.⁷³ Increased TNF leads to increased plasma concentrations of the hormone leptin, effects noted previously.⁷⁴

Anorexia affects 30–40% of adult patients on maintenance hemodialysis; it is associated with greater hospitalization rates, decreased quality of life, and a fourfold increase in mortality.⁷⁵ Uremic toxins including leptin, ghrelin, and neuropeptide Y, as well as altered amino acid pattern and inflammation, are involved.⁷⁶ Studies have shown that injections of uremic ultrafiltrate lead to reduced ingestion of sucrose and mixed nutritional solution in normal rats, although the effect was not specific for one type of nutrient.⁷⁷ Increased frequency of hemodialysis can improve appetite and food intake.⁷⁶