Last update: March 2022
Contact: Aurélie Halsband

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Forms, causes and prevalence of dementia

Irreversible cases, which are mostly neurodegenerative and sometimes neurovascular, are also known as primary dementia. A secondary form of dementia is a functional disorder of brain functions that is fundamentally reversible or curable, such as a brain lesion or neurological disorders caused by poisoning, cardiovascular diseases or thyroid disorders. 

Primary dementia accounts for the vast majority of dementia cases today; the following information in this In Focus refers only to these cases. For forms of primary dementia, 60 % of clinical syndromes in the global north in 2016 were based on Alzheimer's disease. Other neurodegenerative causes include Parkinson's disease, Creutzfeldt-Jakob disease, Huntington's disease, Lewy body dementia and frontotemporal lobar degeneration, but together these account for only about 10 % of cases. Neurovascular forms, on the other hand, account for about 15 % of cases. The same applies to forms of dementia of a mixed type.

The prevalence of dementia diseases, which in most cases do not occur until an advanced biological age, is increasing worldwide due to an overall increase in life expectancy. In 2018, 50 million people worldwide were affected, with estimations for 2021 already at 55 million. In Germany, the number of cases in 2020 was 1.6 million. While only 0.8 % of people in the age of 60 were affected, the rate for those over 80 was 20%, reaching 41 % for those over 90.

Clinical symptoms and stages of dementia

A general diagnosis of dementia is based on the appearance of the first clinical symptoms and evidence of a biological cause of the disease. Standardized procedures are used to assess the symptoms, in particular memory disorders, other cognitive deficits such as impaired planning and organizational skills, and the significant impairment that these disorders cause in coping with everyday life. Furthermore, differential diagnostics exclude other possible causes such as severe depression as cause of the symptoms. The severity of the impairments allows primary forms of dementia to be divided into three phases with varying degrees of clinical symptoms. The first stage is that of mild dementia. Here the short-term memory is already clearly impaired. Sufferers are still able to live alone, but already struggle to cope with more complex tasks. The second stage is moderate dementia, when memory has become nearly non-functional. Although sufferers still understand familiar and habitual routines, up-to-date information about oneself and close persons can no longer be recalled. An independent life is no longer possible. In the third stage, severe dementia, sufferers no longer express clear thoughts and only have very fragmentary memory and routines. They do no longer recognize close persons. This stage may be accompanied by physical impairments such as movement dysfunctions, incontinence and swallowing disorders. Patients are bedridden and at risk of fatal sepsis or pneumonia.

Prediction possibilities and early detection of dementia

Research on predicting dementia aims at predicting the risk of later dementia on the basis of an identified disposition or certain risk factors in a person who is healthy at the time of the study. The possibilities of predicting a later dementia disease are currently very limited. One rare form of Alzheimer's dementia that is inherited in an autosomal dominant pattern can be detected with the help of predictive genetic testing. 

Prediction of dementia must be distinguished from its early detection or early diagnosis, which is aimed at diagnosing a disease in a person who is often still asymptomatic at a particularly early stage. Both research on prediction and early detection are largely focused on the most common form of Alzheimer's dementia. The preclinical phase of Alzheimer's disease already involves systematic neurodegenerative processes. As the brain reserves compensate for the deficits, the disease remains asymptomatic at clinical level. Early diagnosis is aimed at detecting these processes at an early stage and then, ideally, using therapeutic measures to slow down the progression of the processes and the later disease. Current methods for the early detection of Alzheimer's dementia are based on the detection of amyloid plaques, accumulations of the neuronal protein Tau and the detection of specific damage to nerve cells. Particularly so-called cerebrospinal fluid analyses, magnetic resonance imaging and positron emission tomography (PET) enable detection of the aforementioned molecular changes by using so-called biomarkers. 

The presence of so-called mild cognitive impairment (MCI) is particularly important for the early detection of dementia. Mild cognitive impairment can be a permanent cognitive disorder in old age, but it can also be a precursor of subsequently developing dementia. If mild cognitive impairment (MCI) is present and biomarkers show specific molecular changes in the brain that are typical of Alzheimer's dementia, it is possible to make more individual risk assessments. In these cases, it is generally possible to predict dementia. Prediction and early diagnosis methods and their results nevertheless remain fraught with uncertainty in many areas.

Prevention and treatment options for dementia diseases

There is no available cure for Alzheimer's disease and other primary forms of dementia at present. Previously developed drug and non-drug therapies are aimed at slowing down the progression of the disease and its symptoms. This is one of the reasons why the benefits of predictive screening or early medical diagnosis are controversial, regardless of the methodological uncertainties. 

The strategies for preventing dementia are to be distinguished from the treatment options. Prevention starts prior to the development of early symptoms and aims at lifestyle-related reduction of risk factors or improvement of protective factors and at the intervention in molecular processes in order to reduce the number of new cases. Prevention studies may for instance investigate drug interventions that can reduce amyloid plaques before the onset of first symptoms and the possible positive effects of lifestyle adjustments, including social and cognitive activities, nutrition and sleeping habits.

Current research into possible therapies for dementia raises the hope that various interventions can at least delay the course of the disease and its neurodegenerative processes. The aim of combined drug and non-drug therapy approaches is to enable dementia patients to cope with everyday activities independently for as long as possible, to maintain the ability to make their own decisions and to enjoy a good quality of life in general. 

One group of drug therapies targets the regulation of brain messenger substances (neurotransmitters), which is impaired by neurodegenerative processes in Alzheimer's dementia. Another group of drug therapies is aimed at treating accompanying behavioral symptoms such as depression, restlessness, disorientation, insomnia and aggression, which frequently occur in the context of dementia. Antidepressants and neuroleptics can have a positive effect here. Serious behavioral disorders often impair the ability to handle dementia patients and are a major reason for transfer to institutional forms of care and support.

Non-drug therapies also play an important role in the treatment of dementia patients by activating and training physical and cognitive processes. Speech therapy, physiotherapy and occupational therapy, but also approaches such as art and music therapy, are used to specifically delay the onset of primary and secondary symptoms of the disease or to alleviate them after they have occurred. The final, severe phase of dementia usually involves palliative care approaches in the treatment of the affected persons.

Medical care and nursing

Legal regulations for medical care and nursing are of particular importance in the context of people suffering from dementia. In general, the protection of self-determination in the medical context aims to enable patients to give free and informed consent to medical treatment. This also includes the possibility of refusing a measure. With regard to the treatment of people with dementia, the central challenge is to reconcile the decline or complete loss of the ability to consent with the requirement of consent.

Information, education and consent

The provisions of Section 630 of the German Civil Code (BGB) on the so-called treatment contract are authoritative for consent to medical treatment. Treating physicians are obliged to inform patients in particular about the nature, implementation, risks and necessity of treatment. The treatment may only be performed if the patient consents after receiving this information. Information and the requirement of consent are aimed at protecting the patients' self-determination. In line with the principle of informational self-determination and the resulting right not to know, patients, but not those providing treatment, can waive the information requirement. This does not affect the requirement of consent. 

The ability to consent is legally defined as the ability of the patient to understand the nature, meaning and scope of the treatment in basic terms. The extent to which dementia sufferers are able to consent is not determined in general terms, but on basis of the facts of the case at hand. 

If a patient is unable to give consent, e.g. due to advanced dementia, "the consent of a party entitled to do so is to be acquired unless a living will [...] permits or prohibits the measure." (Section 630d(1), sentence 2). Exceptions are treatments that cannot be postponed in case of necessity as justification. Central background information on living wills and necessity as justification can be found in the sections of the same name below.

Power of attorney and custodianship

In anticipation of the possibility that the ability to consent may be impaired at a later point, all persons with still existing legal capacity have the ability to grant power of attorney to relatives or other trusted persons (see further Sections 104 and 1896 BGB). The requirement to consent to or reject treatment is in this case prospectively transferred to others.

Powers of attorney represent a written declaration of intent which entitles a person to take over certain tasks and decisions for the person giving the power of attorney under specific circumstances. A precautionary power of attorney is particularly important because it gives the authorized persons the most extensive decision-making powers, including in medical and nursing contexts. In the early stages of dementia, the patient usually still has the legal capacity required to issue a power of attorney. 

If there is no power of attorney (Section 1896(2), sentence 2) and the legal capacity is already impaired, a custodianship order can be issued. The provisions in Sections 1896-1908 BGB on so-called legal custodianship are authoritative in this respect. These regulate, for instance, the appointment of the natural person who acts as the legal custodian of the person who is then incapable of giving consent. The central task of the custodians is to "attend to the affairs of the person under custodianship in a manner that is conducive to his welfare. The best interests of the person under custodianship also includes the possibility for him, within his capabilities, to shape his life according to his own wishes and ideas." (Section 1901(2) BGB).

Living will

The regulation of the so-called living will in Section 1901a BGB is an important addition to the provisions concerning the persons who have to make decisions for the benefit and in place of persons unable to give their consent. A detailed presentation of the essential regulations as well as the history of the German Living Will Act is presented in the In Focus on Advanced Decisions. 

The core of the regulations, also known as the "Living Will Act", form Sections 1901a, 1901b, 1904 BGB. Section 1901a(1), sentence 1 BGB defines a living will as consent to or prohibition of  "specific tests of his state of health, treatment or medical interventions not yet directly immanent at the time of determination...". Living wills therefore enable patients to determine which medical measures should be taken or not taken in such cases before they become unable to give their consent. The order often includes statements on life-prolonging measures (see the In Focus on Euthanasia for further information). 

A living will is only binding if a person's wishes and expectations as set out in the living will apply to the person's current living and treatment situation (Section 1901a(1), sentence 1 BGB). If a living will has been drawn up lawfully and if the provisions apply to the current living and treatment situation,  custodians or authorized representatives must ensure that the will of the person in question is respected.

If a person is already suffering from dementia, the scope of the living will, which can then still be issued, is measured by the ability at that time to understand the content and scope of the respective decisions and to express a will in this regard (living wills: Section 1901a BGB). 

If there is no living will, or if the determinations of a living will do not correspond to the current situation, the presumed will of the person under custodianship must be determined and observed (Section 1901(2) BGB). The presumed will must be ascertained in accordance with Section 1901a(2), sentence 2 on the basis of concrete indications, taking into account in particular previous oral or written statements, ethical or religious convictions and other personal values of the person under custodianship (Section 1901a(2), sentence 3).

Medical measures that additionally require the approval of a custodianship court

In order to provide special protection for persons incapable of giving consent, under certain circumstances the legislator additionally provides for the requirement of approval of the decisions of custodians or authorized representatives by a custodianship court. Decisions of the custodians or authorized representatives to carry out or refrain from medical measures are then additionally reviewed by a custodianship court if they may result in the death of the person under custodianship or in serious and long-lasting damage to health (Section 1904 BGB) as well as to measures involving deprivation of liberty (Section 1906 BGB) and so-called coercive medical treatment (Section 1906a BGB). 

Such an additional review by a custodianship court is not necessary if an existing living will of the persons under custodianship shows that the implementation or omission of the measure corresponds to the will of the person. Insofar as the living will contains statements to this effect, this also includes the implementation or omission of measures which the person under custodianship, who is already incapable of giving consent, refuses to take. These constellations usually occur in the context of measures that deprive people of their liberty, such as restraint with bed belts or medical treatment which they attempt to evade. In order to ensure that these are measures for the benefit of the person and that it can be assumed that the refusal is due to illness, Sections 1906 and 1906a contain supplementary provisions which must be fulfilled in order to take such measures.

Necessity as justification

If there is necessity as justification (Section 34 StGB; Sections 630d,e BGB) in which a medical intervention must be carried out for the benefit of the 'body' or 'life' of a person suffering from dementia, and if at the same time there is no opportunity to inspect any living will or to question any custodians or representatives, this may also be carried out without consent. In addition to coercive treatment, this includes measures such as confinement or placement in a closed psychiatric facility (Section 1906 BGB; Sections 312 et seq. FamFG). The (subsequent) approval of the custodianship court is usually required for the accommodation of patients.

Criminal responsibility

A person's dementia is not a general reason for his or her diminished responsibility. As with other reasons for a possible diminished responsibility, Sections 20-21 StGB provide for a case-specific analysis in proceedings against persons suffering from dementia that aims to assess whether there are reasons for  reduced or annulled criminal responsibility. In this context, a psychiatric assessment is carried out to determine whether the person's capacity for reasoning or control is impaired. If this is affirmed in the respective individual case of a person suffering from dementia as a consequence of the illness, this can influence the interpretation of criminal responsibility.

Fitness to drive

According to Section 2 of the Road Traffic Act (StVG), participation in road traffic without a driving license is not permitted in Germany. Section 11 of the Driving License Ordinance (FeV) lists the conditions under which the absence of the necessary physical and mental abilities to drive motor vehicles can result in the driving license being revoked. Appendix 4 a, paragraph 3 also lists under 7.3 "severe senile dementia and severe personality changes due to pathological aging processes" as a disease that can justify a medical-psychological assessment of a person's fitness to drive motor vehicles. Such an assessment is based on an evaluation of the skills required for driving, including tests of attention, reaction and visual abilities.

In cases in which a person suffering from dementia is clearly impaired in his or her fitness to drive but continues to do so regardless, the relevant regulations concerning the suspension of medical confidentiality towards authorities and regulations concerning compensation for damages by relatives liable for supervision pursuant to Section 832 BGB may apply.

As dementia progresses, there are significant losses of cognitive abilities and often personality changes. This raises ethical challenges in dealing with dementia patients. Obstacles and uncertainties are encountered in particular when applying established ethical principles.

Dementia and the status as persons

In ethical contexts, certain protection claims are often limited to persons. At the same time, the concept of a person is usually defined on the basis of demanding cognitive capabilities, which include a self-aware reference to the future, the (diachronic) consistent pursuit of preferences over longer periods of time, a reflective evaluation of one's own wishes and actions, and moral motivation and accountability. However, this results in the problematic consequence that dementia patients in the late stages of the disease are no longer considered persons in the true sense of the word, even if we continue to treat them as persons. This view is countered by the objection that passive components of personality remain intact even in the case of dementia and constitute a separate phase of personal life, or that basal forms or core elements of personhood that are less dependent, or not at all, on developed cognitive abilities are still present even in late phases of the disease. From the perspective of theological ethics, the continuing core of personhood of an individual is also emphasized.

Dementia and the continuity of the person in time

There is also uncertainty as to whether a patient in the late stages of the disease is still the same person that he or she was at the beginning or before the onset of the disease, so that, for example, a time-delayed self-determination through earlier expressions of will can be meaningfully achieved. This is not only about possible qualitative changes in personality, but also about the problem of whether at some stage another person may start to inhabit the same body when the current consciousness is no longer linked to the earlier stages of life by memories. An established model of thinking sees the continuity of the person as being based on psychological connections to the past. 

This view is countered by the fact that at least fragments of long-term memory are often retained until the end in dementia. These isolated recalls of long-term memory by persons with dementia would therefore provide at least a fragmentary psychological link to their past and thus their continuity as persons.

Another alternative is to base the person's continued diachronic existence rather on physical or neural criteria. Overall, however, it can be concluded that an ethical orientation for normative questions, which cannot be answered without a clarification about the continuity of personal existence across time, is made more difficult by a lack of consensus on the criteria for this diachronic continuation.

Dementia and communication

Problems in the application of ethical principles also arise due to the very limited verbal communication with people in the late stages of dementia, whose verbal ability is already greatly reduced. Protecting the autonomy of the patient faces the difficulty that current expressions of will are no longer clearly understandable or carry an increased risk of misunderstanding. The same is true for applying duties of care and the duty to avoid harm in the face of uncertainty as to whether concrete expressions should be interpreted as an expression of positive feelings or of discomfort. At least to a certain extent, however, facial expressions and gestures can still provide differentiated information about wishes and sensitivities.

Dementia and self-determination

The ethical difficulties associated with the principle of enabling dementia patients to have as much self-determination as possible in the long term are particularly manifold. 

A conventional institution for safeguarding patient autonomy is the time-delayed effective self-determination by means of a living will, in which a person can stipulate bindingly which medical measures should be taken or omitted if he or she is later unable to make a decision. This form of deferred self-determination is initially based on the previously mentioned, uncertain assumption that the person with dementia is still identical to the competent author of the living will.

In addition to the question of the continuity between the person afflicted with dementia and the still competent person before the onset of the illness, there is the problem that current expressions of will of a person with dementia can contradict the autonomous will of the person still fully capable of making decisions. A prominent example of such a case of conflicting expressions of will is the case of a former rhetoric professor from Tübingen, Walter Jens, who in the stage of advanced dementia expressed a situational will to live that contradicted earlier statements of his own in which he had rejected life-sustaining measures in the case of advanced dementia. This raises the difficult question of whether, in such a case, the predetermining autonomous will should be given greater weight or the so-called "natural will", which is expressed in the later situational expression. Opinions differ on this in ethical discourse, as exemplified by the Dworkin-Dresser debate. In 2012, the German Ethics Council advocated that, in view of the irreversible consequences of failing to take life-saving measures, life-affirming expressions of will in cases where the ability to make decisions cannot be reliably ruled out should be regarded as remnants of self-determination even if they conflict with the advance directives expressed in a living will. 

If a person with dementia harms himself or herself through his or her behavior, it is particularly urgent to discuss to what extent the self-determination of a dementia sufferer who is legally incapable of giving consent can or must be subordinated to the care for his or her physical well-being. This debate also includes the discussion around the ethical admissibility of coercive measures such as force-feeding or confinement measures such as restraint, which are legally permissible under certain conditions but ethically controversial.

In addition to ethical questions regarding the ability of dementia patients to consent, the right to self-determination also raises ethical questions in the context of medical information. An additional field of application for aspects of autonomy is the decision to undergo a predictive diagnosis in the case of so-called mild cognitive impairment. Here the aspect of informational self-determination comes into play, which according to conventional understanding includes a right not to know. Not least in view of the predictive uncertainties and the limited therapeutic options available, this right not to know is promoted vigorously within the ethical debate in such cases.