Older People - Patterns of Illness, Physiological Changes and Multiple Pathology

Original Editor - Bhanu Ramaswamy as part of the AGILE Project.

Top Contributors - Evan Thomas, Lucinda hampton, Kim Jackson, Amrita Patro and Vidya Acharya


Good Practice

Distinguishing the accumulation of age related disease (morbidity) from true ageing is difficult. An important aspect of management of older adults is to recognise and understand how body systems are interlinked. Awareness of pathological and normal age-related physiological changes will assist your assessments and help you decide on best management of older people.

Don't approach this section with a feeling of impending doom. Also remember that not everyone experiences all mentioned issues, and those with disabling conditions have often accommodated to the changes without too much of an impact on their lifestyle.

In earlier life, the signs and symptoms of illness might be explained by a single diagnosis. In older people, the number of active or inactive pathological processes might compromise both the precise diagnosis as a basis of treatment, and include or be impacted on by a further disability. Hence awareness of different pathological processes and of normal age-related physiological changes will assist your assessment and management of older people.

Discussion Point

‘True ageing should be universal and observed in all older members of a species. It should be intrinsic, that is, attributable to basic mechanisms innate to the organism and not exclusively due to modifiable environmental effects. It should be progressive in that it is seen as a gradual process of accumulated damage and decline.’ (Gershon and Gershon, 2000) This decade-old statement still holds true.

As we live longer, degenerative problems are becoming pre-eminent in older age and much of health care practice falls within the category of ‘longer-term / chronic' conditions. In many of these conditions, by the time they manifest themselves a successful cure is elusive. Distinguishing the accumulation of age related disease (morbidity) from true ageing is difficult. Izaks and Westendorp[1] theorise a relationship between age and disease, placing them on either side of a continuum and finding little to distinguish between them.

Certain commonly seen conditions are liable to be disregarded by the individual, relatives or by the doctor as they develop slowly. For example, gradual onset of alterations in voice, in facial appearance, cold sensitivity, lethargy and slowing may be easily attributable to the ageing process that myxoedema (decreased activity of the thyroid gland) can be overlooked. Postural changes, stiffness and restricted activity often considered a part of ageing may cause the rigidity and bradykinesia of Parkinson’s to be missed. Investigations are often provoked due to comments from a visitor, especially one who has not seen the person for a long time and to whom the changes are noticeable. It is useful to identify underlying mechanisms that lead to true age related changes, as opposed to age related disease.

Altered responses to illness

Illnesses often present differently in old age than in youth. Regulation of body temperature is unstable or less responsive, so pyrexia may not be as marked as would be expected even in severe infections such as pneumonia, appendicitis or pyelonephritis. The converse, a lack of awareness of cold, or of the capacity to react normally to it, may lead to hypothermia.

Delirium is characterised by an acute, fluctuating change in mental status with inattention and altered levels of consciousness. Categories include hyperactive delirium, characterised by agitation and visual hallucinations, as opposed to hypoactive delirium characterised by lethargy and withdrawal. Precipitating factors including immobility, malnutrition, intercurrent illness, dehydration and, stress of admission to hospital or other unfamiliar settings[2].

Pain is common in older people. However as people age, they complain less of pain. The reason may be a decrease in the body's sensitivity to pain or a more stoical attitude toward pain. Some older people mistakenly think that pain is an unavoidable part of ageing and thus minimise it or do not report it. Even in conditions that cause intense pain in earlier life (e.g. angina or fractures), there may be so little discomfort, or pain is referred in such a bizarre way, that diagnosis is delayed – sometimes with fatal consequences. Pain is often not correctly recognised and treated in people with dementia, and use of a scale such as the Abbey pain scale may help to recognise when a person is in pain.

Response to drugs also alters with age.

Recovery from illness is often slower, owing to inter-current infections or to the debilitating nature of the condition. Conversely, some old people may make remarkable and quite unexpected recoveries from severe mental or physical impairment.

See also Perceptions about Ageing and Ageism 


  1. Izaks G and Westendorp R (2003). Ill or just old? Towards a conceptual framework of the relation between ageing and disease. BMC Geriatrics, 3(7). www.biomedcentral.com/1471-2318/3/7
  2. Elie M, Cole MG, Primeau FJ, Bellavance F (1998). Delirium Risk Factors in Elderly Hospitalized Patients. J Gen Intern Med; 13(3): 204–212