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Keywords:

  • dementia;
  • depression;
  • depressive delusions;
  • pseudodementia

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. RELATIONSHIP BETWEEN DEPRESSION AND DEMENTIA
  5. PSEUDODEMENTIA AND PSYCHOLOGICAL TENSION
  6. TREATMENT STRATEGY IN VIEW OF THE DEPRESSION–DEMENTIA MEDIUS
  7. REFERENCES

Depression and dementia, among the most common conditions in clinical practice, sometimes coexist, sometimes succeed each other, and often confuse clinicians. In the present paper, the clinical concept of ‘depression–dementia medius’ (which includes pseudodementia and depression in Alzheimer's disease as exemplars) is proposed, in reference to Janet's concept of psychological tension. Because psychosomatically complex human lives are always in a state of dynamic equilibrium, it seems sensible to propose that pseudodementia and depression in Alzheimer's disease are located within a spectrum extending from depression without dementia symptoms to dementia without depression. From the Janetian viewpoint, pseudodementia is regarded as uncovered latent dementia as a result of reduced psychological tension. Dementia is more than a fixed progressive condition under this view, and is a manifestation of dynamic mental activities. Characterizing these entities through perspectives such as psychological tension may yield deep insights in clinical practice.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. RELATIONSHIP BETWEEN DEPRESSION AND DEMENTIA
  5. PSEUDODEMENTIA AND PSYCHOLOGICAL TENSION
  6. TREATMENT STRATEGY IN VIEW OF THE DEPRESSION–DEMENTIA MEDIUS
  7. REFERENCES

In rapidly aging societies, clinicians are faced with ever increasing numbers of mentally disordered elderly people, with depression and dementia being among the most common in clinical practice. The conundrum is that both conditions sometimes coexist, can sometimes succeed each other, and often confuse clinicians. Marin1 argued that depression can be distinguished from apathy in dementia by emotional responses expressed as negative thoughts about the self, the present, and the future, in addition to despair, helplessness, and pessimism. Purandare et al.2 pointed out that depressive symptoms such as sadness, diurnal variation in mood, and early and late insomnia are able to differentiate major depression from Alzheimer's disease (AD). However, the distinction is not always clear in clinical situations.

Our clinical experience with elderly patients who subsequently develop dementia after the onset of depression, those with residual dementia after treatment for depression, and those with reversible dementia-like symptoms (i.e. pseudodementia) suggests that depression and dementia are often not clearly distinguishable states, but may coexist or interpenetrate each other. Future advances in medical science and technology, including the development of biomarkers and diagnostic functional imaging technology, may enable more distinguishing diagnoses; still, clinicians need a conceptual ‘compass’ to approach the complex clinical problems in psychogeriatrics. In the present paper, the clinical concept of a ‘depression–dementia medius’ (which includes pseudodementia and depression in AD as exemplars) is proposed. Then, the relationship between depression and the manifestation of dementia symptoms is discussed from a broader standpoint, referring to Janet's concept of psychological tension.3

RELATIONSHIP BETWEEN DEPRESSION AND DEMENTIA

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. RELATIONSHIP BETWEEN DEPRESSION AND DEMENTIA
  5. PSEUDODEMENTIA AND PSYCHOLOGICAL TENSION
  6. TREATMENT STRATEGY IN VIEW OF THE DEPRESSION–DEMENTIA MEDIUS
  7. REFERENCES

The existing psychiatric literature presents certain perspectives on the relationship between depression and dementia.

Jorm4 introduced six possible hypotheses explaining the association as follows: (i) depression treatment is a risk factor for dementia; (ii) dementia and depression share common risk factors; (iii) depression is a prodrome of dementia; (iv) depression is an early reaction to cognitive decline; (v) depression affects the threshold of manifesting dementia; and (vi) depression is a causal factor in dementia.

The first hypothesis suggests that electroconvulsive therapy or antidepressant drugs are possible causal factors in dementia, whereas the second corresponds approximately to the 19th century concept that mental illness is the result of evolutionary ‘degeneration’. Jorm4 believed there is little support for either of these two hypotheses. Rather, Kessing et al. reported that continued long-term antidepressant treatment was associated with a reduction in the rate of dementia.5 The third and fourth hypotheses are possible. Some reports suggest that late-onset depressive symptoms or syndromes are a prodrome of cognitive decline6–9 or early manifestations of dementia.10,11 Rubin et al. showed that depression is common among patients with mild and moderate dementia, but is less common in severe AD.12 The sixth hypothesis seems to be untenable without reservation. However, several reports provide evidence that depression is an independent risk factor for AD.7,13–16 The idea that depression affects the threshold of manifesting dementia is somewhat related to our ideas; we believe there may not be a single correct answer and, rather, suggest a complicated association between depression and dementia.

As for depression (or depressive states) complicated with dementia, Lee and Lyketsos17 classified causes of depression in AD into four categories that may overlap each other: (i) psychological reaction to cognitive decline; (ii) recurrence of early and mid-life major and minor depression; (iii) ‘vascular depression’; and (iv) the degenerative process of AD. Applied to traditional causal theory, their classification indicates that depression in AD can be endogenous, exogenous, or psychogenic and may be polygenetic. That is, ‘depression’ in the English-language literature can refer to a depressive symptom complex or non-specific depressive state on one occasion, and the operational criteria for major depression or endogenous depression (in the traditional diagnostic sense) on another. In the present paper, we focus on mid-life endogenous depression or later, especially presenile and senile, endogenous depression.

According to the reviews of Jorm5 and Tsuno and Homma,18 authors of prospective studies are in disagreement about whether depression is a risk factor for dementia. Some authors found associations between dementia and depressive episodes of a decade or a quarter of a century earlier.19,20 Others found associations between dementia and a preceding but recent depression.7,9,13,21,22 There are also researchers who reject the association altogether.23,24

In this regard, it is worth noting that patients with depression in their 20s and 30s rarely present with pseudodementia; depressive patients with pseudodementia are exclusively in their mid-life or later. We illuminate two clinical courses of the depression–dementia complex: one where dementia-like symptoms emerge in depression and the other where early dementia is complicated by depression. In the former case, if dementia-like symptoms are expressed prominently, the condition may be called pseudodementia. We hypothesize that pseudodementia is a revelation of latent dementia in depressive illness. The patients who recover from pseudodementia are apt to develop apparent dementia several years later. Alexopoulos and Chester reported that approximately 4% of cognitively intact elderly depressive patients develop dementia within a year.25 As for the latter, prevalence rates for significant depressive symptomatology in AD range from 15%26 to as high as 50%.27 In accord with findings like this, Olin et al., investigators with extensive research and clinical experience in both late-life depression and AD, proposed provisional criteria for depression in AD.28 They listed clinically significant depressed mood, decreased positive affect or pleasure in response to social contact and their usual activities, disruptions in appetite and sleep etc. as depressive symptoms. Their proposal, in which depression is mentioned as part of the symptomatology of AD, may be evaluated as a rapid response to the social needs that have arisen in this aging society; however, it is problematic.

Patients who meet these criteria must meet the criteria of AD and their symptoms are not better accounted for by other conditions, such as major depressive disorder, bipolar disorder etc. Thus, the depression in AD they are considering must be a mild case. If depressive symptoms were severe enough to meet the criteria of major depressive disorder, the diagnosis of AD may be called into question. In this instance, diagnosis of pseudodementia has to be considered. The American group seemed to overlook the possibility that even patients with mild depressive symptoms can develop pseudodementia. When AD is diagnosed, the depression-based reversible dementia-like state (pseudodementia) must be ruled out. The provisional criteria for depression in AD are inadequate from this standpoint.

In contrast, the concept of ‘depression in AD’ requires a rethinking of the diagnosis of pseudodementia. Detailed clinical observation of patients with pseudodementia sometimes reveals comorbidity with mild cognitive impairment or early stage AD.

Nevertheless, our clinical experiences tell us two things: (i) significant endogenous depression can present as pseudodementia that antidepressive agents can completely cure; and (ii) some patients with AD present with depressive states in the early stages, which partially respond to antidepressive agents.

In 1993, Emery and Oxman29 already proposed viewing depression, cognitive impairment, and degenerative dementia as intersecting continua. They suggested that the cognitive impairment of depression is interpreted as a continuum intersecting an organic degenerative continuum with a corresponding continuum of reversibility–irreversibility. The aspect we are going to illustrate is similar to theirs, but more dynamic, pliable, and clinically available.

When we regard human life as a psychosomatic complex in a state of incessant dynamic equilibrium,30 it seems sensible to view pseudodementia and depression in AD as being located in a spectrum extending from depression without dementia symptoms to dementia without depression. Then, we can locate pseudodementia and depression in dementia in the zone between depression and dementia; that is, in the ‘depression–dementia medius’ (Fig. 1; note, all figures are derived from our preliminary essay on this issue31). Needless to say, the human brain is an organ with large standby capacity: if it were partially destroyed by cerebrovascular disease or brain contusion, the surviving parts could compensate at least partially for the lost function.30 When we consider the manifestation of dementia symptoms, we must look from the viewpoint of this dynamic equilibrium.

image

Figure 1. Mechanism of manifesting depressive pseudodementia. (Reproduced with permission from Kato and Kobayashi.31)

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The central nervous system in presenile and senile periods is inevitably involved with the aging process to a greater or lesser extent and, at first, this process may take the form of insidious cognitive impairment. However, this type of cognitive impairment is assumed to be commonly compensated by repair mechanisms of the brain and may remain latent. When such a person develops depression, latent dementia may surface under conditions of impaired compensatory mechanisms in the brain due to functional incapacity caused by depression, including a diminished ability to concentrate and an inability to make decisions. When the patient recovers from depression, and concentration levels improve, dementia returns to latency. Under the advancement of the aging process, compensation is no longer possible and latent dementia again surfaces in everyday life. The further advancement of aging discourages the manifestation of depression and dementia plays a key role in the patient's medical condition.

We intend to set up a psychopathological perspective of the relationship between depression and the manifestation of dementia, from a broader standpoint,32 referring to the concept of psychological tension by Janet.3

PSEUDODEMENTIA AND PSYCHOLOGICAL TENSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. RELATIONSHIP BETWEEN DEPRESSION AND DEMENTIA
  5. PSEUDODEMENTIA AND PSYCHOLOGICAL TENSION
  6. TREATMENT STRATEGY IN VIEW OF THE DEPRESSION–DEMENTIA MEDIUS
  7. REFERENCES

The concept of pseudodementia is not clearly defined. Each author uses this term according to his or her own definition. Because of the ambiguity of the term, some authors33–35 recommend that it is not used. The ‘pseudo’ of pseudodementia may contain two implications: one is that a reversible dementia-like state is dementia in disguise because genuine dementia is irreversible; the other is that the relevant state is not genuine dementia but a dementia-like state due to other mental disorders. Historically, the first user of this term was said to be Wernicke, who described pseudodementia in a patient with hysteria,36 while Ganser's37 contribution to the same condition is well known. The move towards defining34 pseudodementia due to depression as depressive pseudodementia dates back to Mairet, who presented the concept of démence melancholique in 1883.38 After Wernicke, this term was forgotten until Kiloh,39 in 1961, took notice of reversible dementia-like states or reversible cognitive dysfunction in depressive patients. The concept of pseudodementia as an atypical type of depression is clinically worth re-evaluating because it is a treatable cognitive dysfunction under treatments for depression. Nussbaum,33 who recommended dropping the term, also indicated the importance of raising alarms about the existence of treatable cognitive dysfunction.

Now we would like to illuminate the pathogenesis of pseudodementia, applying Janet's3 concept of psychological force (force psychologique) and psychological tension (tension psychologique). To evaluate human mental activity, Janet introduced two parameters: psychological force and psychological tension. Psychological force, in this view, is nearly identical to biological power, which every individual naturally embodies and that provides a platform for abilities of swift, long-lasting, and multifaceted actions. Psychological tension indicates the ability to use psychological force to drive appropriate behavior in social situations. Greater psychological tension is required to perform more complex and more varied operations. Janet compared psychological force and tension to assets and their management, or military strength and strategy.

Janet's concept can be illustrated as follows using military strength and strategy as analogies. When we do a job in our workplace or are involved with community activities, we need not only a fundamental source of energy to implement the behavior, but a certain level of strategy as to how to do it. When we have a higher-level strategy in place, we can lay out our military strength and do a job efficiently. If we only have a low-level strategy, we would likely allocate military strength on a hit-or-miss basis, leading to incoherent behavior and eventually delusions.

Aging is a situation in which military strength is reduced at first. We can imagine an old man who is mentally fit but physically weak. Even with reduced military strength, having a high-level strategy enables one to smartly deploy one's strengths and adapt to changing reality. The so-called wise old person can demonstrate astonishing adaptation to reality even with reduced military strength and a high-order strategy.

Conversely, senile depression is characterized as a condition of reduced military strength with further reduced levels of strategy. We can see that impairment of concentration and inability to make decisions, central features of depression, directly relate to Janet's strategy, which is to say, psychological tension. In the case of depressive delusions, it is interpreted as a misdirected allocation of military strength caused by deterioration in the quality of strategy.

As to depressive pseudodementia, depressive states cause temporary declines in psychological tension, or reductions in the level of strategy, and subsequently reveal latent dementia. The progression of dementia from pseudodementia is a continuous process of decline of psychological tension (Fig. 2).

image

Figure 2. Dementia coexisting with depression. (Reproduced with permission from Kato and Kobayashi.31)

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Nevertheless, as is generally the case with aging, dementia is by no means an endogenous biological linear process. It develops in connection with various psychosocial situations and becomes a clinical case. There is some sense that dementia, like schizophrenia and depression, is regulated by a ‘triple helix’;40 that is, the double helix of DNA plus the third ‘helix’ of the psychosocial situation. In fact, a considerable number of patients exhibits dementia when put in situations in which higher psychological tension is required, including admission to hospital alone, starting single life, or moving to a new place of residence (Fig. 3). In those cases, the curved line indicating the relationship between psychological tension and cognitive impairment moves to the right, and patients exhibit more severe dementia even if they keep the same level of psychological tension.

image

Figure 3. Revelation of latent dementia. (Reproduced with permission from Kato and Kobayashi.31)

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Furthermore, when a patient is disappointed at his/her inability to adjust to the new environment and becomes depressed, this depression would lead to a further decline of psychological tension and subsequent deterioration of dementia.

TREATMENT STRATEGY IN VIEW OF THE DEPRESSION–DEMENTIA MEDIUS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. RELATIONSHIP BETWEEN DEPRESSION AND DEMENTIA
  5. PSEUDODEMENTIA AND PSYCHOLOGICAL TENSION
  6. TREATMENT STRATEGY IN VIEW OF THE DEPRESSION–DEMENTIA MEDIUS
  7. REFERENCES

Dementia is usually thought to be an irreversible condition; however, patients in the depression–dementia medius have the potential to resist dementia. What a therapist tries to do first is to provide an environment that the patient with lower levels of psychological tension can manage. When a person is placed in a new environment, he/she requires higher levels of psychological tension. Hospitalization, requiring higher levels of psychological tension, should be avoided for as long as possible. Family nursing in the hospital is preferable. The nursing staff require sensitivity to minimize environmental changes during a hospital stay (Fig. 4).

image

Figure 4. Possible therapeutic management. (Reproduced with permission from Kato and Kobayashi.31)

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The therapist has to take measures to elevate the patient's level of psychological tension as high as possible, including measures to improve the depressive state. It is worth trying antidepressants for those patients with dementia who exhibit no apparent depressive symptoms, with careful attention to the adverse effects. Modified electroconvulsive therapy can be efficacious for antidepressant-resistant cases. Rao and Lyketsos41 concluded that electroconvulsive therapy is an effective treatment for depression in dementia, leading to improvements in both mood and cognition. Broad-based psychotherapy that enhances self-esteem is also important: music therapy42 and reminiscence therapy43 are also thought to elevate the level of psychological tension.

Under recent operational diagnostic criteria, which have no category for pseudodementia, clinicians are likely to misdiagnose depressive pseudodementia as AD. Antidepressants are the first line of treatment for depressive pseudodementia, although there is controversy regarding maintenance treatment with antidepressants. If antidepressants are administered, the dose must be as low as possible, because pseudodementia may reflect progression of latent dementia. Maintenance treatment with donepezil may be considered.

In summary, we would like to emphasize in this paper that dementia is more than a fixed progressive condition: it is a manifestation of dynamic mental activities. Characterizing these entities beyond the detailed observation of each individual symptom, through perspectives such as psychological tension, may yield deep insights in clinical practice.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. RELATIONSHIP BETWEEN DEPRESSION AND DEMENTIA
  5. PSEUDODEMENTIA AND PSYCHOLOGICAL TENSION
  6. TREATMENT STRATEGY IN VIEW OF THE DEPRESSION–DEMENTIA MEDIUS
  7. REFERENCES