The potential influence of age and aging on the psychological functioning of people with disabilities is surprisingly complex. In people with spinal cord injury or multiple sclerosis, depression is highly prevalent. The limited research in this area indicates that older age and greater time span since disability onset may be associated with less self-reported depressive symptoms. Posttraumatic growth (PTG) and benefit finding (BF) are also common in people with disabilities. Older age tends to be associated with less BF and PTG. Studies that use longitudinal designs and examine multiple age-related factors simultaneously are needed. Potential mediators of age-related effects, such as historical trends, life-cycle events, maturity, and declining health, also need to be examined. There are many interesting theoretic and empiric concepts from aging research that can inform future research on the psychological aspects of aging with disability.
In this article the authors examine the intersecting influences of age-related factors and disability on psychological functioning. The scope of this study has been restricted to people with multiple sclerosis (MS) and people with spinal cord injury (SCI) because there is a well-developed research literature on psychological factors in these 2 groups. Furthermore, this article focuses on depression, as it is arguably the most commonly studied psychological condition in persons with disability. However, this review also includes a discussion of positive psychological concepts such as posttraumatic growth (PTG) and benefit finding (BF), which are particularly important given that most individuals achieve healthy psychological adjustment despite the challenges of aging and disability. In addition, a better understanding of healthy functioning may help improve the lives of people with disabilities at least as much as understanding less adaptive functioning.
It would be optimal if researchers consistently used widely accepted nosology and valid diagnostic interviews, such as the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV), to identify specific pathologic conditions such as major depressive disorder (MDD). In most cases, however, self-report measures are used to measure constructs or identify cases. Even well-developed, widely used, self-report measures usually lack proven diagnostic accuracy, especially in the context of disability. Therefore, in this article, terms such as “depression” and “depressive symptomatology” are used to refer to nondiagnostic approaches and self-report measures of negative affect. The use of these terms should not be misconstrued to indicate the presence of a diagnosable psychiatric condition. The authors have used diagnostic terminology such as “major depressive disorder” only when the assessment is based on widely accepted diagnostic criteria, and a reliable and valid evaluation process.
Age-related concepts are surprisingly complex and merit some explanation. Age factors addressed in the disability literature to which we refer include age at the onset of diagnosis of the condition, time since diagnosis or onset, chronologic age at the time of assessment, and the historical era (eg, the “cohort”; the early 1900s, the 1960s). In addition, aging can represent different phenomena, especially with regard to depression. Aging can represent larger historical trends when, for example, a higher rate of depression is associated with lower education among older cohorts who tended to have lower educational achievement. Aging may also represent life cycle events. For example, depression may be higher in older adults because older age is associated with retirement, widowhood, and other possible depressogenic loss experiences. Aging may represent a decline in health. Depression in old age may be attributable to poorer health and functional decline than in chronologic age. Older age may also represent differential survival. Because survival into old age may be lower because of depression, a lower rate of depression in older adults may represent preferential survival of more healthy individuals. Alternatively, women tend to survive longer than men and women are characterized by higher rates of depression. Consequently, a higher rate of depression in older adults may be attributable to differential survival of women. Finally, aging may represent greater maturity, psychological integration, or improvements in coping. Lower rates of depression may be associated with older age to the extent that old age–related improvements in insight, self-integration, and self-esteem buffer depression risk. For example, socio-emotional selectivity theory posits that when one perceives that one has less time left to live, one reorganizes one’s goals to more closely conform to what one can realistically accomplish. A similar process may influence adjustment to and aging with disabilities.
This complexity means that age-related theoretic influences may operate differently based on study design. Cross-sectional aging studies may be confounded by historical trends. In the case of aging with disability, an important historical trend is the changes in the nature and length of rehabilitation programs over the past 50 years. Longitudinal studies may be confounded by differential survival. In people with SCI, a salient fact is that there has been a 2000% increase in life expectancy over the past 50 years. Depression-related risk factors, such as low education, loss events, poorer health, accelerated functional decline, differential survival, and the wisdom of maturity, may complicate studies of aging with disability because these risk factors may be more common, more salient, or occur earlier in people with disabilities. The trajectories of key variables, such as functional impairments, are specific to the type of disability, for example, immediate decline plus aging effects in people with SCI versus variable decline plus aging effects in people with MS. Finally, these age-related theoretic factors may operate differently with regard to the various psychological concepts such as depression versus posttraumatic growth or resilience. Clearly, the literature on psychological adjustment in persons aging with disability is complex and multifaceted, which may in part explain the few studies published in this area.
Depression and aging factors in the general population
Overall, global measures of subjective well-being improve through adulthood. Most older adults adjust well to aging, and most older adults with disabilities, such as SCI, do not report significant depressive symptoms. Similarly, older adults tend to have lower rates of MDD compared with younger adults or about the same prevalence. Prevalence rates of DSM-IV MDD are 1% to 3% in the general elderly population. Among older people sampled in primary medical care, settings rates of MDD are 5% to17%. Nevertheless, older adults are more likely than younger adults to report subclinical symptoms of depression (about 16% in the community, or 29% in primary care settings). Older adults tend to have a different presentation of depression, including more anhedonia and lack of energy, lower prevalence of dysphoria, less guilt, less passive suicidal ideation, and more prominent somatic symptoms, such as fatigue and poor appetite. This presentation has been called “depletion syndrome” and “nondysphoric depression.” When older adults are clinically depressed, prognosis and impairment are worse compared with younger persons. Among clinically depressed older adults undergoing treatment as usual, at 24 months 33% were well, 33% remained depressed, and 21% had deceased. Depressed adults (with or without MDD) have poorer overall functioning, comparable or worse than that of people with heart and lung disease, diabetes, and so forth. Depression increases the perception of poor health, which is one of the most salient predictors of mortality in older people.
Depression and aging in people with SCI
Depression is thought to be the most prevalent and disabling psychological condition associated with SCI. Depression is not considered a stage in the process of healthy adaptation to catastrophic injury, but a comorbid condition that merits assessment and treatment. The overall prevalence of major depression is 15% to 23% in most studies that use diagnostic interviews. Moreover, depressive symptoms are linked to a myriad of negative outcomes including poorer subjective health, poorer community integration, more secondary conditions, and higher rates of suicide.
The authors searched PubMed and PsychLit for papers with the key words such as SCI, depression, and age or aging. Study reference lists were also searched for additional papers that mentioned these 3 topics. Table 1 displays the subset of studies that analyzed depression and age-related factors in people with SCI. Studies are difficult to compare because of the use of diverse measures of depression ranging from psychometrically sound instruments to single item indicators. Studies also focused on different age-related concepts and used several designs. One study by Tate and colleagues excluded people with major depression and therefore was not included in this review. Glass and colleagues used an unfamiliar depression measure and reported depression prevalence that was inconsistent with the rest of the studies.
| Author, Year | Number | Mean Age | Mean Years Since SCI | Results |
|---|---|---|---|---|
| Schulz & Decker, 1985 | 100 | 56 | 20 | Cross-sectional study; mean CESD scores = 9.74 among persons at an average of 20 y post SCI; 22% scored in the depressed range |
| Holicky & Charlifue, 1999 | 225 | ≥26 | Cross-sectional study; mean CESD scores = 11.5 among unmarried versus 10.1 for married; among married, CESD scores are highest for those aged 50–59 y and lower in earlier and later age cohorts; for unmarried, CESD scores decline in each successive age cohort | |
| Kemp & Krause, 1999 | 177 | 40 | 14 | Cross-sectional study in people at an average 14 y after SCI; 17% scored in depressed range on GDS |
| Glass et al, 1999 | 287 | 35 | 6 | Cross-sectional study; 66% scored in depressed range on IDA scale; those older than 50 y had higher depression scores but greater time since injury was associated with lower depression scores |
| Krause et al, 2000 | 1391 | 42 | 10 | Cross-sectional study; 24% scored in the probable major depression range on the OAHMQ; the percentage with probable major depression levels increased with greater age and age at injury onset; higher rates of probable major depression were observed in cases with the most years post injury (26 y or more) and those with the least years post injury (1–5 y) |
| Charlifue & Gerhart, 2004 | 178 | 59 | 36 | 6-y longitudinal study; trend toward increased depression on CESD over 6 y (means = 9.4, 10.2, 11.5 in years 1993, 1996, 1999, respectively) |
| Charlifue & Gerhart, 2004 | 189 | 59 | 36 | 6-y longitudinal study of quality of life; lower quality of life was associated with greater subsequent depression on CESD |
| Bombardier et al, 2004 | 849 | 37 | 1 | Cross-sectional study of people 1 y post SCI; rate of probable MDD on PHQ-9 was significantly higher among people aged 25–49 y (15.0%), compared with older (8.7%) or younger (6.5%) age groups |
| Saikkonen et al, 2004 | 76 | ∼51 | ∼10 | Cross-sectional study with 31% scoring in depressed range on BDI; higher BDI scores were correlated with age at time of injury (r = 0.35) and year of injury (r = 0.52). Those injured between the age of 46 and 60 y had a mean BDI score of 11.6 vs a mean of 9.4 among those more than 60 y old. Those injured in the 1990s had higher BDI scores than those who had been injured earlier |
| Richardson & Richards, 2008 | Total n = 2570 | 38–49 | 1, 5, 15, 25 | Compared cohorts assessed at 1, 5, 15, 25 y post SCI; mean PHQ-9 scores are significantly lower for 15 and 25 y post SCI (M = 3.8, 3.5, respectively) compared with 1 and 5 y post SCI (M = 5.4, 4.7, respectively) |
| Hitzig et al, 2008 | 781 | 51 | 14 | Cross-sectional study with about 33% indicating on a single item that they experienced depression in the past year; odds of depression decreased as years post SCI increased |
Among studies reporting rates of depression in people living 10 or more years after SCI, depression prevalence ranged from 17% to 33%. Although depression prevalence in these samples is certainly higher than rates of MDD in nondisabled aging samples, it does not appear different from the average prevalence rate observed in SCI and depression studies generally. Only 1 study examined the relationship of depression to chronologic age at the time of assessment and found a weakly positive relationship. With regard to age at the time of injury, 2 studies found that an older cohort was less likely to be depressed compared with a younger cohort. The most consistent finding in cross-sectional studies was an inverse relationship between depression and time since injury. Krause and colleagues reported a similar pattern with those 1 to 5 years post SCI having higher rates of probable major depression compared with those 6 to 25 years after injury. However, the oldest group, those living with SCI for 26 years or more, was also more likely to be depressed compared with those 6 to 25 years post injury. In contrast, the only longitudinal study of depression found that there was a nonsignificant trend toward increased depression over 6 years. A parallel longitudinal study of quality of life suggested that declines in quality of life preceded increased depression. Only 1 study examined depression as related to historical trends finding that depression rates were higher in the 1990s compared with the previous decades. Few studies reported on more than one age-related factor (see Table 1 ).
The research on depression and aging in SCI leaves many questions unanswered. Studies of people with SCI are generally consistent with research in the nondisabled population in that depression is less pronounced in older than in younger cohorts. However, it may also be that depressive symptoms follow a U-shape in terms of severity, with increasing report of depressive symptoms in mid-life. Studies are needed that explicitly examine the relationship of multiple age-related factors to depression. These studies should include suspected moderators of age-related effects on depression such as education, life cycle events, changes in health, and changes in coping. Aging studies with longitudinal designs and studies that examine the health and quality of life correlates of depression at different ages are needed. For example, it has been suggested that the impact of physical health conditions on depression is mediated by restriction of normal activities, and that older adults may find this activity restriction less distressing. However, this has never been tested in an aging population with disability. There are many rich empiric and theoretic concepts from the general aging literature that may be applicable to studies of aging with SCI.
Depression and aging in people with SCI
Depression is thought to be the most prevalent and disabling psychological condition associated with SCI. Depression is not considered a stage in the process of healthy adaptation to catastrophic injury, but a comorbid condition that merits assessment and treatment. The overall prevalence of major depression is 15% to 23% in most studies that use diagnostic interviews. Moreover, depressive symptoms are linked to a myriad of negative outcomes including poorer subjective health, poorer community integration, more secondary conditions, and higher rates of suicide.
The authors searched PubMed and PsychLit for papers with the key words such as SCI, depression, and age or aging. Study reference lists were also searched for additional papers that mentioned these 3 topics. Table 1 displays the subset of studies that analyzed depression and age-related factors in people with SCI. Studies are difficult to compare because of the use of diverse measures of depression ranging from psychometrically sound instruments to single item indicators. Studies also focused on different age-related concepts and used several designs. One study by Tate and colleagues excluded people with major depression and therefore was not included in this review. Glass and colleagues used an unfamiliar depression measure and reported depression prevalence that was inconsistent with the rest of the studies.
| Author, Year | Number | Mean Age | Mean Years Since SCI | Results |
|---|---|---|---|---|
| Schulz & Decker, 1985 | 100 | 56 | 20 | Cross-sectional study; mean CESD scores = 9.74 among persons at an average of 20 y post SCI; 22% scored in the depressed range |
| Holicky & Charlifue, 1999 | 225 | ≥26 | Cross-sectional study; mean CESD scores = 11.5 among unmarried versus 10.1 for married; among married, CESD scores are highest for those aged 50–59 y and lower in earlier and later age cohorts; for unmarried, CESD scores decline in each successive age cohort | |
| Kemp & Krause, 1999 | 177 | 40 | 14 | Cross-sectional study in people at an average 14 y after SCI; 17% scored in depressed range on GDS |
| Glass et al, 1999 | 287 | 35 | 6 | Cross-sectional study; 66% scored in depressed range on IDA scale; those older than 50 y had higher depression scores but greater time since injury was associated with lower depression scores |
| Krause et al, 2000 | 1391 | 42 | 10 | Cross-sectional study; 24% scored in the probable major depression range on the OAHMQ; the percentage with probable major depression levels increased with greater age and age at injury onset; higher rates of probable major depression were observed in cases with the most years post injury (26 y or more) and those with the least years post injury (1–5 y) |
| Charlifue & Gerhart, 2004 | 178 | 59 | 36 | 6-y longitudinal study; trend toward increased depression on CESD over 6 y (means = 9.4, 10.2, 11.5 in years 1993, 1996, 1999, respectively) |
| Charlifue & Gerhart, 2004 | 189 | 59 | 36 | 6-y longitudinal study of quality of life; lower quality of life was associated with greater subsequent depression on CESD |
| Bombardier et al, 2004 | 849 | 37 | 1 | Cross-sectional study of people 1 y post SCI; rate of probable MDD on PHQ-9 was significantly higher among people aged 25–49 y (15.0%), compared with older (8.7%) or younger (6.5%) age groups |
| Saikkonen et al, 2004 | 76 | ∼51 | ∼10 | Cross-sectional study with 31% scoring in depressed range on BDI; higher BDI scores were correlated with age at time of injury (r = 0.35) and year of injury (r = 0.52). Those injured between the age of 46 and 60 y had a mean BDI score of 11.6 vs a mean of 9.4 among those more than 60 y old. Those injured in the 1990s had higher BDI scores than those who had been injured earlier |
| Richardson & Richards, 2008 | Total n = 2570 | 38–49 | 1, 5, 15, 25 | Compared cohorts assessed at 1, 5, 15, 25 y post SCI; mean PHQ-9 scores are significantly lower for 15 and 25 y post SCI (M = 3.8, 3.5, respectively) compared with 1 and 5 y post SCI (M = 5.4, 4.7, respectively) |
| Hitzig et al, 2008 | 781 | 51 | 14 | Cross-sectional study with about 33% indicating on a single item that they experienced depression in the past year; odds of depression decreased as years post SCI increased |
Among studies reporting rates of depression in people living 10 or more years after SCI, depression prevalence ranged from 17% to 33%. Although depression prevalence in these samples is certainly higher than rates of MDD in nondisabled aging samples, it does not appear different from the average prevalence rate observed in SCI and depression studies generally. Only 1 study examined the relationship of depression to chronologic age at the time of assessment and found a weakly positive relationship. With regard to age at the time of injury, 2 studies found that an older cohort was less likely to be depressed compared with a younger cohort. The most consistent finding in cross-sectional studies was an inverse relationship between depression and time since injury. Krause and colleagues reported a similar pattern with those 1 to 5 years post SCI having higher rates of probable major depression compared with those 6 to 25 years after injury. However, the oldest group, those living with SCI for 26 years or more, was also more likely to be depressed compared with those 6 to 25 years post injury. In contrast, the only longitudinal study of depression found that there was a nonsignificant trend toward increased depression over 6 years. A parallel longitudinal study of quality of life suggested that declines in quality of life preceded increased depression. Only 1 study examined depression as related to historical trends finding that depression rates were higher in the 1990s compared with the previous decades. Few studies reported on more than one age-related factor (see Table 1 ).
The research on depression and aging in SCI leaves many questions unanswered. Studies of people with SCI are generally consistent with research in the nondisabled population in that depression is less pronounced in older than in younger cohorts. However, it may also be that depressive symptoms follow a U-shape in terms of severity, with increasing report of depressive symptoms in mid-life. Studies are needed that explicitly examine the relationship of multiple age-related factors to depression. These studies should include suspected moderators of age-related effects on depression such as education, life cycle events, changes in health, and changes in coping. Aging studies with longitudinal designs and studies that examine the health and quality of life correlates of depression at different ages are needed. For example, it has been suggested that the impact of physical health conditions on depression is mediated by restriction of normal activities, and that older adults may find this activity restriction less distressing. However, this has never been tested in an aging population with disability. There are many rich empiric and theoretic concepts from the general aging literature that may be applicable to studies of aging with SCI.
Depression and aging in people with MS
A meta-analysis found depression to be more prevalent among people with MS compared with the general population and individuals with other neurologic conditions. In one of the few prospective epidemiologic studies, MDD had a 12-month period prevalence of 15.7% in MS, which is twice the prevalence in the general population. High rates of clinically significant depressive symptoms have been reported in numerous studies of community dwelling individuals with MS. When present, depression adversely affects other domains of functioning, including cognition, fatigue, functioning, and quality of life.
To examine relationships between aging and depression in MS, PubMed and PsychLit were searched for papers with the key words such as multiple sclerosis, depression, and age or aging. Study reference lists were also searched for additional papers that included these 3 key words. Given the large volume of studies published on MS and depression, only studies published in 2000 or later were included in the table. Table 2 displays the subset of studies that analyzed depression and age-related factors in people with MS. Like the SCI studies, cross-study comparisons are difficult because of the diversity of measures.
| Author, Year | Number | Mean Age | Mean Years Since MS Diagnosis | Results |
|---|---|---|---|---|
| Patten et al, 2000 | 136 | 47 | 9 | Cross-sectional population-based Canadian clinic sample; Using the CIDI-A, 23% met DMS-IV criteria for lifetime major depression; 4% had current major depression; 13% reported single episodes of major depression, and 10% reported recurrent episodes. Younger age (<35) associated with greater risk for lifetime major depression (OR = 4.6) |
| Chwastiak et al, 2002 | 730 | 49 | 13 | Cross-sectional study of community dwelling adults; mean CESD score for sample = 16.0; 45% had CESD score ≥16; 29% score ≥21 on CESD suggestive of probably major depression; younger age was associated with greater risk for depression (≥16 on CESD) |
| Patten et al, 2003 | 115,071, 332 with MS | NR | NR | Cross-sectional national survey (Canadians); Using the CIDI, the annual prevalence of major depression in MS was 16% compared with 7% in adults without MS; major depression was more prevalent in those <45 y of age (26%) compared with those 45 y or older (8%) |
| Galeazzi et al, 2005 | 50 | 35 | 10 | Cross-sectional; age and duration of MS were not associated with presence of a DSM-IV depressive disorder (based on SCID) |
| Williams et al, 2005 | 451 | 55 | 18 | Cross-sectional survey of US veterans; 22% had current major depressive episode on the PHQ-9; 32% met criteria for a major or minor depressive episode on PHQ. Younger age was a significant risk factor for a current major depressive episode (OR = 0.97). Shorter duration of MS was associated with greater risk for depression |
| Arnett & Randolph, 2006 | 53 | 47 | 7 | 3-y longitudinal study; examined the course and reliable change of different depressive symptom clusters and association with interferon β treatment/coping; mood symptoms more variable over time than neurovegetative or negative evaluative symptoms; age was not associated with the findings; investigators did not report % depressed |
| Beal et al, 2007 | 607 | 51 | 13 | Longitudinal study at 7 y; younger age and longer duration of MS were associated with greater depressive symptoms at time 1 y but did not predict changes in depressive symptoms over time. Greater functional limitations were associated with greater depressive symptoms at all time points |
| Tsivgoulis et al, 2007 | 86 | 39 | 6 | Cross-sectional sample; age and duration of MS were not associated with depression symptom severity as measured on BDI |
| Bamer et al, 2008 | 530 | 52 | 15 | Cross-sectional study of community dwelling adults in a more rural community; 51% had CESD score ≥16, 34% score ≥21 on CESD, suggestive of probably major depression; age was not associated with depression |
| Beiske et al, 2008 | 140 | NR | 19 | Cross-sectional study; 31% had depression on HSCL-25; younger age at onset of MS was related to presence of depression |
| Phillips & Stuifbergen, 2008 | 443 | 56 | 19 | Cross-sectional; lower age was associated with greater depressive symptoms |
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