MARCO TEORICO ESPECIFICO

Definitional problems underlie debates about prevalence and etiology. For this reason, different classification systems are reviewed and the effect of differences in criteria on decisions about diagnosis and rates of disorder is explored. The most commonly accepted classifications of mood disorders are those in the Diagnostic and statistical manual of mental disorders (4th Edition; DSM-IV; American Psychiatric Association, 1994) and the Interna-tional classification of disease (10th Edition;

ICD-10; World Health Organization, 1992).

These include depressive disorders (major depressive disorder and dysthymic disorder) and bipolar disorders. It is not clear, however, how fully these conventional diagnostic cate-gories represent the experience of affective disorders among older adults. For this reason, descriptions of several subtypes of depression are also presented that may better capture the syndromes prevalent in late life.

7.09.2.1 Standardized Classification Systems 7.09.2.1.1 DSM-IV

Major depressive disorder is defined in the DSM-IV by the presence most of the day, nearly every day, of dysphoria (depressed mood), Mood Disorders in Late Life

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anhedonia (diminished interest or pleasure in all or nearly all activities), appetite or weight disturbance, sleep disturbance, psychomotor agitation or retardation, loss of energy, worth-lessness or guilt, inability to concentrate, and/or recurrent thoughts of death or suicide. At least five symptoms must be present, of which one must be either dysphoria or anhedonia. Symp-toms attributed to uncomplicated bereavement, the direct physiological effects of a medical condition, or use of a substance (including medications), are excluded. A diagnosis of depressive disorder is made, however, if symp-toms in a bereaved person persist longer than two months or include marked functional impairment, morbid preoccupation with worth-lessness, suicidal ideation, psychotic symptoms, or psychomotor retardation.

Dysthymic disorder is characterized by chronicity and a lower level of severity than major depression. Depressive symptoms must be present for at least two years. If criteria for both major depressive and dysthymic disorder are met, both diagnoses are assigned, a condition commonly referred to as double depression.

Bipolar-I disorder is marked by alternating major depressive and manic episodes, resulting in impaired functioning. If the manic episodes are briefer and do not interfere with functioning (i.e., hypomanic episodes), the diagnosis of bipolar-II is assigned. Hypomanic episodes alternating with dysthymic symptoms are classified as cyclothymic disorder.

Depressive symptoms that do not meet the above diagnostic criteria, but can be attributed to a specific stressor, may be classified as adjustment disorder with depressed mood.

7.09.2.1.2 ICD-10

There is much similarity between ICD-10 and DSM-IV for mood disorders. Depressive dis-orders are classified by severity, with moderate and severe equivalent to the DSM-IV category of major depressive disorder, and mild episode more closely resembling the provisional cate-gory of minor depression in the appendix of DSM-IV. ICD-10 criteria for bipolar affective disorder, dysthymia, and cyclothymia are equivalent to the corresponding DSM-IV categories.

7.09.2.1.3 Earlier versions of DSM and ICD Much of the currently available research on mood disorders is based on earlier versions of DSM and ICD, including DSM-III (American Psychiatric Association, 1980), DSM-III-R (American Psychiatric Association, 1987),

ICD-9-CM (Commission on Professional Hos-pital Activities, 1978), and ICD-9 (World Health Organization, 1977), or on the Research Diagnostic Criteria (RDC; Spitzer, Endicott, &

Robins, 1978). The RDC influenced changes appearing in DSM-III, which was published shortly thereafter. RDC mood disorder classi-fications include: major depressive disorder, minor depressive disorder, bipolar with mania I), bipolar with hypomania (bipolar-II), and intermittent depressive disorder.

Changes in DSM categories since 1980 have been minimal, while some ICD classifications have been completely reworked during this time frame.

In the DSM, criteria for mood disorder have become somewhat more stringent with later revisions. A requirement that symptoms be clinically significant or cause impaired social, occupational, or other functioning was intro-duced in the DSM-III-R for dysthymia and in the DSM-IV for major depressive disorder. This criterion could affect diagnosis in older adults disproportionally, who may be less likely to engage in social or occupational roles in which impaired functioning could be observed. There have been significant changes in the specifica-tion of melancholic features, with DSM-IV criteria more closely resembling DSM-III than DSM-III-R. Bipolar-II disorder was added to DSM-IV as a new classification.

Perhaps the greatest changes have occurred between ICD-9 and ICD-10. In the earlier version, mood disorders were classified as either a neurotic disorder or an affective psychosis.

Since diagnostic criteria were not specified in detail in ICD-9, precise comparisons of classi-fications are not possible. Affective psychosis approximates the ICD-10 category of depressive disorder with somatic symptoms, while a neurotic depression would be diagnosed in ICD-10 as either depressive disorder without somatic symptoms or dysthymia. Due to the differences between classification systems (par-ticularly between ICD-9 and all other systems), caution should be exercised when comparing results of studies that were not based on a common rubric.

7.09.2.2 Symptom Presentation in Late Life Although some scholars emphasize simila-rities between older and younger individuals in the experience of depressive symptoms, there is also an accumulating body of research identifying differences in symptom presentation in late life (for a review, see Caine, Lyness, King,

& Connors, 1994). The most frequent differ-ences include: lower prevalence of dysphoria,

fewer ideational symptoms (e.g., guilt, suicidal ideation), and increases in selected somatic symptoms.

Several authors have reported a decreased likelihood of dysphoria as a symptom of depression in old age (e.g., Kongstvedt &

Sime, 1992). In the Epidemiologic Catchment Area (ECA) sample, Gallo, Anthony, and MutheÂn (1994) found that older individuals were less likely to endorse an item comprising dysphoria or anhedonia than younger respon-dents with the same level of overall depression.

Using a self-report symptom checklist, Gatz and Hurwicz (1990) found that depressed mood was neither higher nor lower in older adults;

however, the older adults in their sample were less likely than other age groups to endorse items on a well-being subscale. Consequently, these authors speculate that older adults may be more likely to experience a lack of positive feelings than active negative feelings.

Age differences in ideational symptoms among depressed patients have been described by Musetti et al. (1989) and Small, Komanduri, Gitlin, and Jarvik (1986). They found lower levels of guilt and lower levels of a factor including self-blame and suicidal ideation. Even though older adults are more likely to complete acts of suicide than younger individuals (Gul-binat, 1996), they appear to be less likely to display suicidal ideation (Blazer, Bachar, &

Hughes, 1987; Brown, Sweeney, Loutsch, Kocsis, & Frances, 1984). Brown et al. noted that lower levels of guilt were characteristic of late-onset cases.

The central question about somatic symp-toms in depressed older adults is whether they are reliable indicators of depression or merely an artifact of the high comorbidity of physical illness in this age group. Blazer et al. (1987) found that older adults with melancholia were more likely than younger adults to have weight loss and constipation. In patients with major depression, older adults have been found more likely to have delusions, agitation, appetite disturbance, initial insomnia, and hypochon-driasis than younger patients (Brodaty et al.

1991; Brown et al. 1984). No difference in somatic symptom presentation was found between early- and late-onset cases. Other investigators have found no age differences in somatic symptoms or preoccupation with physical health, either in depressed psychiatric patients (Kongstvedt & Sime, 1992) or among male patients with medical problems (Koenig, Cohen, Blazer, Krishnan, & Silbert, 1993).

Using self-report depression symptom instru-ments, Kessler, Foster, Webster, and House (1992) found similar relationships with age for both mood and somatic symptom subscales.

Finally, Davidson, Feldman, and Crawford (1994) found that physically disabled older adults who scored high on the somatic factor tended to score high on the other factors as well.

Regardless of how common or uncommon specific symptoms are in older adults, it is also important to know which of them are useful prognostically. The particular symptoms that best distinguish depressed from nondepressed older individuals seem to include loss of interest, lack of energy, sleep disturbance, suicidal thoughts, and feeling blue (Koenig et al., 1993; Norris, Snow-Turek, & Blankenship, 1995). Fatigue and changes in appetite and sexual activity did not, and may reflect physical comorbidity or normal aging.

7.09.2.3 Subtypes

Knowledge of the depressive symptoms most frequently experienced by older adults informs the discussion of several subtypes of depression or symptom constellations thought to be relevant in later life. The subtypes reviewed here include ones that can be accommodated within the diagnostic rubric (melancholia and delusional depression), experimental diagnostic categories (minor depression and mixed anxiety±depression), and other syndromes that may occur in older adults (masked depression, depletion syndrome, and hopelessness depres-sion). There is also considerable convergence across many of these entities.

7.09.2.3.1 Melancholic

In the DSM-IV, individuals with a unique pattern of symptoms, including nearly complete loss of pleasure in most activities, lack of reactivity to pleasurable stimuli, a distinct quality of mood, depression worse in the morning, early waking, psychomotor retarda-tion or agitaretarda-tion, weight loss, and excessive guilt, are diagnosed with major depressive disorder with melancholic features. At least one of the first two symptoms must be present.

The criteria for melancholia in ICD-10, referred to as ªsomatic symptoms,º includes the same symptom pattern as ªmelancholic featuresº in DSM-IV with the exception of distinct quality of depressed mood and excessive guilt. The term ªendogenousº has also been used to refer to melancholic depression.

7.09.2.3.2 Delusional depression

Delusional depression is a depressive disorder with the presence of mood-incongruent delu-sions. It is diagnosed in DSM-IV and ICD-10 by specifying psychotic features/symptoms. In Mood Disorders in Late Life

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ICD-10, psychotic symptoms are further classi-fied as mood-congruent or incongruent. There is mixed evidence concerning the relationship between delusional depression and age of onset.

Meyers, Greenberg, and Mei-Tal (1985) found delusional depression to be more common in later-onset cases and in late-onset endogenous depression (Meyers, Kalayam & Mei-Tal, 1984). As mentioned earlier, Brodaty et al.

(1991) found delusions to be more common in older adults than in younger adults. Nelson, Conwell, Kim, and Mazure (1989) and Baldwin (1995), on the other hand, found no such association.

7.09.2.3.3 Minor depression

As a result of concerns regarding the validity of diagnostic categories for older adults, the 1991 Consensus Conference on Depression in Late Life issued a call for research on ªminor (subsyndromal) depressionº (Blazer, 1994).

Standardized study criteria for minor depres-sion, included in the appendix of DSM-IV, are the same as those for major depressive disorder but require fewer symptoms. A similar defini-tion has been referred to as ªsubdysthymic depressionº (Mossey, Knott, Higgins, & Taler-ico, 1996) or simply ªdepressive symptomsº (Newmann, 1989; Wells et al., 1989). Several authors have used the term ªminor depression,º but defined it more inclusively, capturing dysthymia and adjustment disorder with de-pressed mood as well as dysphoria (Beekman et al., 1995; Koenig & Blazer, 1992; Parmelee, Katz, & Lawton, 1989).

Beekman et al. (1995) found that risk factors for major depression (family history of depres-sion, previous episodes of depression) differed from those for minor depression (being un-married, having smaller networks of social contacts, living in a large city, chronic disease, and functional limitations). These authors concluded that major depression may be more chronic, while minor depression may be more reactive to stressors. Although minor depres-sion requires fewer symptoms than major depression, and the name implies a syndrome with lesser severity, the Medical Outcomes Study (Wells et al., 1989) revealed that even depressive symptoms in the absence of a depressive disorder were associated with more functional disability than most physical illnesses studied.

7.09.2.3.4 Mixed anxiety±depressive disorder Another experimental category added to DSM-IV that may be relevant to older adults is mixed anxiety±depressive disorder. This

proposed disorder is characterized by a combi-nation of subsyndromal depression and anxiety symptoms. The research criteria require a persistent or recurrent dysphoric mood lasting at least one month, with at least four of these additional symptoms: difficulty concentrating, sleep disturbance, fatigue or low energy, irritability, worry, tearfulness, hypervigilance, anticipating the worst, hopelessness, or low self-esteem. Although mixed anxiety-depression was found in one study to be more prevalent in younger than in older age groups (Blazer et al., 1988), this subtype merits further research in an older population due to the obvious overlap between the specified symptoms and those found commonly in depressed older adults.

7.09.2.3.5 Masked depression

A further term used for older individuals is masked depression (Blumenthal, 1980). Also known as somatic depression, masked depres-sion refers to a predominance of somatic symptoms without mood-related symptoms.

As the term ªmaskedº implies, diagnosis can be difficult due to the absence of the dysphoric mood that characterizes depression.

7.09.2.3.6 Depletion syndrome

Fogel and Fretwell (1985) proposed depletion syndrome as a new subtype of depression, characterized by predominant somatic and vegetative symptoms in depressed older adults with good premorbid psychosocial functioning and no evidence of psychosis. Newmann, Klein, Jensen, and Essex (1996) have pursued this concept, identifying a set of symptoms that occur together more frequently in older adults than in younger individuals. This constellation of symptoms differs from the depression syndrome in that self-deprecating feelings (self-blame and inappropriate guilt) are not present, dysphoric mood items are less prominent, and enervation, loss of interest in things, hope-lessness, and loss of appetite are more promi-nent. Although sleep disturbance is associated with depletion syndrome, it does not include early morning awakening. Newmann et al.

characterize this syndrome as ªquieterº than major depression. In a longitudinal study, they found that individuals with depletion syndrome were more likely to die before the next time of measurement than those with depressive syn-drome, suggesting that depletion syndrome may be related to a wearing down process. It is important to note that the only research on this subtype to date has been in a female population.

7.09.2.3.7 Hopelessness depression

This subtype was developed in younger populations (Abramson, Metalsky, & Alloy, 1989). Like depletion syndrome, it is character-ized by decreased motivation, lack of energy, apathy, and psychomotor retardation, as well as by sad affect. Thus, applicability of this conceptualization to older adults seems war-ranted.

7.09.2.4 Categorical vs. Dimensional Systems Although the focus has been on various categories used to describe mood disorders in older adults, depression has also been con-ceptualized as a continuum. Caine et al. (1994) recommend the use of a dimensional descriptive system encompassing the full range of mood syndromes and comorbid medical conditions.

Unlike categorical diagnostic methods, depres-sive symptom checklists yield a rating on a continuous scale and are inclusive in approach.

In general, scores relating to the presence or severity of individual symptoms are summed to provide a single rating of level of depressive symptomology. Since no symptoms are ex-cluded due to etiology (e.g., bereavement, physical illness), a more complete picture of distress is provided.

7.09.3 PREVALENCE

7.09.3.1 Rates of Mood Disorders

Studies measuring depressive disorders have found a relatively low prevalence in late life. In a review of earlier studies, Kay and Bergmann (1980) concluded that the prevalence of depres-sive neuroses ranged from 4 to 9%, and that field surveys on affective psychoses were too limited to yield reliable information. Table 1 summarizes studies of the prevalence of mood disorders in late life that employed representa-tive sampling methods and large sample sizes.

The one-year prevalence of major depression among individuals aged 65 years and older ranges from a reported low of 0.9% in the ECA survey in the US (Weissman, Bruce, Leaf, Florio, & Holzer, 1991) to a high of 5.7% in a study of ethnic Chinese living in Singapore (Kua, 1992), with more studies finding rates at the low end of this range. Fewer studies have specifically measured rates of dysthymia in an older population. Due to the chronic nature of this disorder, only lifetime rates have been reported. Weissman and Myers (1978) found a 1.8% lifetime prevalence of dysthymic disorder among older adults using RDC. In the more recent ECA study, based on DSM-III criteria,

Weissman et al. (1991) reported an overall rate of dysthymic disorder of 1.7% among those aged 65 years or older. Studies of bipolar disorder in older adults are even more rare.

According to ECA data, one-year prevalence rates of bipolar disorder ranged from 0 to 0.4%

across study sites, for an overall prevalence of 0.1%. Establishing the prevalence of other diagnostic subtypes, such as minor depression, is complicated by varying definitions of these entities.

7.09.3.2 Presence of Depressive Symptoms Several studies have measured the prevalence of clinically significant depressive symptoms, without tying symptoms to diagnostic criteria for a depressive disorder. Rates of mood disorders suggested through the use of clinical cutoffs on depressive symptom checklists are shown in Table 2 for adults aged 65 years and older. These rates range from 9.0 to 16.9%.

Rates found by these studies are generally high compared to studies using diagnostic criteria, as would be expected, since summary scores cannot distinguish between individuals with a disorder and those with subsyndromal levels of symptoms.

7.09.3.3 Age and Depression

In general, epidemiological studies have found lower rates of depressive disorders in older adults compared to other age groups, whereas studies measuring depressive symp-toms have found elevated levels in late life, particularly after age 75 years (see Newmann, 1989, for a review). This outcome lends support to the notion that the symptoms experienced by older individuals may not map well onto existing diagnostic criteria.

The association between age and depression is further complicated by the consistent finding that older individuals report a lower lifetime prevalence of depression compared to younger individuals (Weissman et al., 1991). Since older adults have had more years in which to experience depressive episodes, this finding is remarkable. Several possible explanations have been posited. Some researchers have suggested that later-born generations in the twentieth century have experienced progressively higher rates of depression than those born earlier (e.g., Klerman et al., 1985). This cohort effect could explain relatively low rates of depression among those now old, and would predict that rates of depression in late life would rise as successive generations enter old age. A second hypothesis suggests that lifetime prevalence rates are Mood Disorders in Late Life

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Authors Study Sample N Age

range Measures Diagnostic

criteria Major

depression Minor

depression Dysthymia Bipolar disorder Baltes et al.

(1993);

Wernicke and Linden (1994)

Berlin Aging

Study Stratified random (West Berlin)

156 70+ GMS-A, HAS DSM-III-R 4.8%

Beekman

et al. (1995) Longitudinal Aging Study, Amsterdam

Stratified random (Netherlands)

3056 55±85 DIS, CES-D

(16+) DSM-III 2.0%

m = 1.4%

f = 2.6%

12.9%

m = 9.8%

f = 15.7%

Copeland, Dewey, et al. (1987)

Random^b

(Liverpool) 1070 65+ GMS-A

AGECAT 2.9%

m = 1.7%

f = 3.6%

8.3%m = 5.9%

f = 9.9%

Copeland, Gurland, et al. (1987)

US±UK Cross-National Project

Random (London^b New York)

841 65+ GMS-A

AGECAT 2.5%

m = 1.3%

f = 3.2%

m = 11.8%

f = 17.3%

Henderson

et al. (1993) Canberra-Queanbeyan Study of the Elderly

Random community andinstitutional samples (Australia)

848 70+ Canberra Interview for the Elderly

DSM-III-R

ICD-10 DSM: 1.0%

m = 0.4%

f = 1.5%

ICD: 3.3%^a m = 2.2%^a f = 3.9%^a

Kua (1992) Stratified

random (Singapore)

612 65+ AGMS-A

AGECAT ICD-9 5.7%

Matt, Dean, Wang, and Wood(1992)

Stratified probability (Albany, New

Stratified probability (Albany, New