“Healthy, normally functioning older adults are at no greater risk for depression than are younger adults.” R. E. Roberts, G.A.Kaplan et al, “Does growing old increase the risk for depression?”¹.

“Unlike younger persons with depression, elderly persons with depression usually have a medical comorbidity.” Richard B. Birrer & Sathya P. Vemuri, “Depression in Later Life: a diagnostic and therapeutic challenge”².

In other words, elderly depression is more closely linked to health than it is to age.

The most comprehensive estimates of the place of depression in the worldwide ‘Burden of Disease’ by age, gender and income status were made by Mathers, Lopez & Murray in an extensive 2001 study of “Global Burden of Disease and Risk Factors”3.

They measured Burden of Disease as ‘Disability-Adjusted Life Years’ [DALYs], defined as

Years of Life Lost as a result of premature death +
Years of healthy Life lost as a result of Disability:
DALY = YLL +YLD.

For depression, which is not predominantly a fatal condition, YLL is relatively low whereas YLD is extremely high. Indeed, the study ranks Unipolar Depressive Disorders above any other ailment as a cause of loss of years of healthy life.

The impact of depression is most intensive in high income countries where it is responsible for 11.8% of YLDs from all causes compared with 9.1% in low & middle income countries. The estimates also confirm that women suffer much more extensively from depression than men, though men’s failure to acknowledge, report and seek help for depression (see Article 1) may mean that statistical data under-estimate the male disability effect to some extent...

The same study (Ref.3) has provided an analysis of depression for different age groups in terms of thousands of DALYs from which the following figures per million population have been calculated:

AGE ANALYSIS of Unipolar Depressive Disorders, 2001
(‘000 DALYs per million population, worldwide)

Source: Author’s calculations from data in Mathers, Lopez & Murray [Ref.3]
*’zero’ represents less than 500 DALYs

Years (per million population in each age group) lived with disability as a result of depression rise throughout childhood and youth, reaching peaks in the 30-44 age group for men and in the 45-49 group for women. These peaks are presumably connected with stress in everyday adult life for both sexes, aggravated for women by postpartum and menopausal depression, as well as women’s greater willingness to report the condition. The fact that no gender difference is observed between male and female children might arise from the tendency for children’s depression to be reported by adults.

There is a dramatic fall from the age of 70 onwards for both sexes in both low/middle and high income countries.

These findings are indirectly corroborated by evidence about the so-called ‘U-Curve’ of well-being and happiness over the human life cycle which is at its lowest point of satisfaction with life in middle age. A survey based on data from 55 countries places the bottom of the U-Curve for all participating countries at age 46.1. As many as 47 of the 55 countries record the peak of misery within the age range 40-55, the exceptions being Brazil, Peru, Puerto Rico and Switzerland where the lowest point is under the age of 40; and France, Israel, Russia and Ukraine where it is above the age of 55⁴.

Do these findings of lower prevalence of depression and greater satisfaction with life among the aged mean that elderly depression is not a seriously disabling problem? – By no means!

Elderly depression is complicated by comorbidity to a far greater extent than that of younger persons. The interactive nature of depression, being both cause and consequence of other illnesses, makes the elderly much more vulnerable to a variety of chronic diseases. This constitutes a ‘burden’ for society that is linked not so much to the number of depressed elderly patients as to the complexity of their treatment. This involves higher cost in time, money and health care resources, and is aggravated by inadequate, inappropriate or ineffective measures that leave elderly patients disabled with both depression and other illnesses. Moreover, the rapidly rising proportion of the over-60s (and above all the over-80s) in the population of high income countries foreshadows elderly depression as a growing trend. As yet, society appears largely unprepared for the implications.

Differences between the causes and symptoms of depression in elderly and younger persons are not absolutely clear-cut. In some respects, they overlap. Yet research has shown that some factors are far more pronounced in the elderly than in younger persons (and vice versa). These point to important implications for the prevention, diagnosis and treatment of elderly depression.

Recent findings of the Zürich Study of younger persons (stretching over 20 years with an age range of 20-41) have pointed to high levels of medical comorbidity between long–term depression and cardiac and respiratory problems, insomnia, pain (other than backache and headache) and sexual problems. Interestingly, the authors ascribe the cardiac and respiratory problems in this age group as probably ‘associated with increased anxiety’⁵.

In the elderly, by contrast, the main areas of medical comorbidity with depression are chronic conditions that are largely the result of ageing: stroke, hypertension, atrial fibrillation, diabetes, cancer and dementia are singled out as risk factors for elderly depression by WebMD6. Elsewhere, Parkinson’s Disease, thyroid deficiency and adverse reactions caused by the simultaneous administration of a variety of interactive medicines to elderly patients [‘polypharmacy’] are also cited.

The Zürich Study also investigated psychiatric comorbidities with depression in the 20-41 age group. The six leading risk factors were found to be tobacco dependence, substance abuse, generalized anxiety disorder, obsessive-compulsive syndrome, panic attacks and alcohol use disorder (Ref.5). Again, with the exception of anxiety, these are probably more prominent risk factors for depression in younger persons than for the elderly. The psychosocial impact of bereavement, loneliness and growing physical and cognitive problems in coping with the normal activities of daily life are more characteristic associations with depression in old age.

Common risk factors for depression among both elderly and younger persons that are less specifically related to calendar age are insomnia, and pain associated with anxiety.

One other aspect is adding to the difficulty of drawing unequivocal conclusions about elderly depression: major national differences in its prevalence, revealed in the Survey of Health, Aging and Retirement in Europe [SHARE]⁷. Analysis of community dwellers aged 50+ (standardised for 5 factors including age differences in the national composition of samples) showed about 50% greater prevalence of depression in Latin countries (France, Italy, Spain) than in Sweden, Denmark, Netherlands, Germany, Austria, Switzerland and Greece. This divergence is thought to be at least in part cultural, though other factors may also be involved.

This discussion still leaves unanswered the question why the disability impact of depression (per million people in each age group) should be so much lower among the elderly than in early adulthood or middle age. One hypothesis that has been advanced is that elderly attitudes towards their own problems gradually change with advancing age. In effect, the elderly are not a homogeneous segment of the population, and should not be perceived or treated as such. Their circumstances and attitudes can change materially with positive or negative effect between the early and late phases of old age.

The authors of a study of differences in depressive symptoms between functionally impaired persons in the age groups 55-64, 65-74, and 75+ observed that “despite their objectively poor physical and functional health status, those in the 75 age group may have better perceptions of their own health than those in the 55-64 age group” as a result of ‘positive ageing’⁸. Adaptation to the difficulties of old age is gradual. Its problems are often most worrying and least acceptable in the earlier phases of ageing. Such an explanation could raise important new issues for the professional approach to prevention and treatment of depression at different stages of the ageing process from being ‘elderly’ to joining the ‘oldest old’.

However, before considering new approaches, it will be useful to take stock of current international practice in the diagnosis and treatment of elderly depression, including the frequently observed catalogue of failures of diagnosis or treatment, and patients’ failure to adhere to prescribed treatment. These topics, together with effective practice, will be the subject of the third article in this series.

Footnotes:
[1] American J Psychiatry 154 [10],  1384-1390, October 1997
[2] American Family Physician 69[10], 2367-2382, 2004
[3] C. D. Mathers, A. D. Lopez & C. J. C. Murray,  Chapter 3: “The Burden of Disease and Mortality by Condition: Data, Methods and Results for 2001”, World Bank Group, New York, Oxford University Press 2006
[4] D. G. Blanchflower & A. J. Oswald, “”Is well-being U-shaped over the life cycle?”,  Social Science & Medicine, 66, 1733-1749, 2008
[5] J. Angst, A. Gamma et al, “Long-term depression versus episodic major depression: results from the prospective Zürich study of a community sample”, J. Affective Disorders 115, 112-121, 2009
[6] http://www.webmd.com/depression/guide/depression-elderly , reviewed by M. Hoffman, MD, 28 April 2008
[7] E. Castro-Costa, M. Dewey et al, “Prevalence of depressive symptoms and syndromes in later life in ten European countries”, The SHARE Study, British J. Psychiatry 191, 393-401, 2007
[8] N. G. Choi & J. S. Kim, “Age group differences in depressive symptoms among older adults with functional impairments”, Health & Social Work 32[3], 177-188, August 2007

Related articles:
Elderly Depression: Its Prevalence, Causes and Implications for Society 1/4
Elderly depression: are doctors and patients failing to connect? 3/4
Elderly depression: the pitfalls of comorbidity and polypharmacy 4/4