Depression

The Science of Mental Health

Steven E. Hyman

• Publisher: Routledge
• Year: 2013
• Print ISBN: 9780815337492
• eBook ISBN: 9781135712815
• Topic: Medicine
• Subtopic: Mental Health in Psychology

First Published in 2002. In common usage, the term "depression" can refer to the state of being sad or blue, but it also signifies a serious clinical syndrome that affects approximately 10 percent of people at some point in their lives. This clinical syndrome may occur as a primary illness or as a complication of ("secondary to") another mental disorder such as schizophrenia, a medical condition such as hypothyroidism, or the effects of a drug. Based on studies of clinical courses and outcomes, treatment responses, and familial patterns of depression, primary depressive illness is dichotomized into unipolar (depressions only) and bipolar. In bipolar disorder, or manic-depressive illness, depressions are interspersed with manias- periods of elevated mood, high energy, and lack of sleep. Bipolar disorder is described in a separate volume.

Depressive Symptomatology and Incident Cognitive Decline in an Elderly Community Sample

Shari S. Bassuk, ScD; Lisa F. Berkman, PhD; David Wypij, PhD

Background: It is not known whether depression is a cause or consequence of progressive cognitive decline. We assessed the relationship between depressive symptoms and subsequent cognitive decline in the community-dwelling elderly population.

Methods: Data were from a population-based cohort study that enrolled 2812 noninstinationalized elderly residents of New Haven, Conn, and followed them with in-home visits in 1982, 1985, 1988, and 1994. Cognitive function was assessed with the Short Portable Mental Status Questionnaire (SPMSQ). Response to the SPMSQ was scored as high, medium, and low, and cognitive decline was defined as a transition to a lower category. Depressive symptoms were measured with the Center for Epidemiological Studies Depression Scale.

Results: An elevated level of depressive symptoms was associated with an increased risk of incident cognitive decline among medium SPMSQ performers (3-year odds ratio [OR], 1.72; 95% confidence interval [CI], 1.04–2.82, P=.03; 6-year OR, 2.40; 95% CI, 1.33–4.34; P=.004; 12-year OR, 1.65; 95% CI, 0.62–4.38; P=.31) but not among high performers (3-year OR, 0.93; 95% CI, 0.62–1.39; P=.71; 6-year OR, 1.03; 95% CI, 0.67–1.58; P=.90; 12-year OR, 1.26; 95% CI, 0.59–2.71; P=.55), after adjustment for age, sex, race, education, income, housing type, functional disability, cardiovascular profile, and alcohol use.

Conclusions: Depressive symptoms, particularly dysphoric mood, presage future cognitive losses among elderly persons with moderate cognitive impairments. However, the data do not provide support for the hypothesis that depressive symptoms are associated with the onset or rate of cognitive decline among cognitively intact elderly persons.

Arch Gen Psychiatry. 1998;55:1073–1081

From the Departments of Epidemiology (Drs Bassuk and Berkman), Health and Social Behavior (Dr Berkman), and Biostatistics (Dr Wypij), Harvard School of Public Health, Boston, Mass.

IT IS NOT known whether depression, particularly at subclinical levels, contributes to the onset or course of cognitive decline in old age or instead is a consequence of cognitive impairment. Epidemiologic studies have been primarily limited to cross-sectional investigations that are consistent in showing a positive correlation between depressive symptoms and poorer cognitive performance in putatively nonde-mented individuals,^1–3 as well as between depressive symptoms and severe cognitive deficits indicative of dementia in population-based samples,^4–7 but reveal little about the causal direction of this association.

See also page 1082

Dementia, defined as chronic and substantial decline in 2 or more areas of cognitive function sufficient to interfere significantly with work, social activities, and interpersonal relationships, affects an estimated 15% of the United States population older than 65 years.⁸ Clinical and neu-ropathologic studies suggest that Alzheimer disease (AD) accounts for at least 50% of dementia cases.⁹ Caring for dementia patients imposes enormous psychosocial and economic burdens on family and other caregivers.¹⁰ In the United States, the total societal cost of caring for all persons first diagnosed with AD in 1991 alone has been estimated at $67.3 billion.¹¹ Aside from age and genetic factors,¹² there are few established risk factors for AD.⁹

Case-control investigations of depression and cognitive function have focused on AD patients. A pooled reanalysis of studies conducted before 1990 suggests that a history of medically treated depression occurring at least 1 year prior to AD

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SUBJECTS AND METHODS

RESPONDENTS

The study population was drawn from the New Haven, Conn, site of the Established Populations for Epidemiologic Studies of the Elderly (EPESE) project, described in detail elsewhere.¹⁸ The New Haven cohort is a multistage probability sample of 2812 noninstitutionalized persons 65 years and older living in New Haven in 1982. Samples were drawn from 3 housing strata: public housing for elderly persons (age- and income-restricted), private housing for elderly persons (age-restricted), and community housing. All eligible men were sampled; women were randomly sub-sampled to achieve roughly equal representation of both sexes. The response rate at baseline was 82%. Trained lay examiners interviewed the cohort in their homes in 1982, 1985,1988, and 1994 and by telephone in intervening years.

MEASURES

Cognitive Function

Cognitive performance was measured during in-home interviews with the 10-item Short Portable Mental Status Questionnaire¹⁹ (SPMSQ). (The original item “What is the name of this place?” was changed to “What is your address?” as this seemed more appropriate for community-dwelling residents.) Correct answers receive 1 point; possible scores range from 0 to 10. If 4 or more items were refused or missing, the SPMSQ was not scored. Otherwise, refusals were scored as incorrect, and scores on missing items were imputed by assigning the mean of nonmissing items. For some analyses, we trichotomized scores into 3 categories: high (9–10), medium (7–8), and low (0–6).

Depressive Symptomatology

The Center for Epidemiological Studies Depression Scale²⁰ (CES-D), a self-report measure of current depressive symptomatology, was administered during in-home interviews. Possible scores range from 0 to 60; higher scores indicate more severe symptoms. The conventional cutpoint of 16 was used to classify respondents as “depressed” or “nondepressed.” For some analyses, depressed respondents were further subdivided into cases of “severe” (CES-D score ≥26) vs “mild/moderate” (16≤ CES-D score ≤25) depression based on tertiles of the CES-D distribution. An alternative scoring approach employed a diagnostic algorithm²¹designed to capture the presence of dysphoria (low mood), considered the essential feature of clinical depression.²²

Covariates

The following self-reported variables were viewed as potential confounders because of their associations with depressive symptoms or cognitive function among New Haven²³ or other community-dwelling elders,”^4,16 or because of their status as established risk factors for vascular dementia,²⁴ the most common cause of progressive cognitive decline in elderly persons after AD²⁵: age (coded as a continuous covariate); sex; race (white or nonwhite); education (≥12 or <12 years); yearly income (<$5000, ≥$5000, or missing); housing; functional disability (defined as requiring assistance with 1 or more activities of daily living²⁶ [walking across a room, dressing, eating, bed-to-chair transferring, bathing, using toilet]); cardiovascular profile (low- or high-risk, where high-risk is defined as a history of physician-diagnosed stroke, diabetes, myocardial infarction, or a measured sitting blood pressure of at least 160/95 mm Hg); and cigarette and alcohol consumption.

diagnosis is associated with an elevated risk of dementia in persons 70 years and older.¹³ However, a recent case-control study that paid closer attention to the temporal ordering between depression and dementia found that treated depression occurring more than 1 year prior to earliest AD symptoms did not predict AD onset.¹⁴ Two recently published cohort studies of depression and subsequent cognitive impairment also yield discrepant results. Devanand et al¹⁵ report that depressed mood was strongly predictive of incident AD among 478 individuals identified through a New York City dementia registry and followed from 1 to 5 years. In contrast, Dufouil et al¹⁶ found that depressive symptoms were not associated with cognitive deterioration during a 3-year period in a community-based sample of 1600 elderly French persons.

Given the inconclusive evidence, additional population-based longitudinal investigations are needed. We determined whether an elevated level of depressive symptomatology is predictive of an increased incidence of cognitive impairment or a faster rate of cognitive decline in a cohort of community-dwelling elderly persons. Clarifying the temporal relationship between depressive states and cognitive dysfunction may be helpful in elucidating the etiology of these conditions. Furthermore, given the failure of many primary ca...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Content
• Introduction
• Epidemiology
• Natural History
• Depression and Medical Disorders
• Genes and Environment
• Evolution
• Neurobiology and Behavior
• Treatment Outcomes