CHAPTER 48 Dementia and Delirium

Scott J. Saccomano, PhD, GNP-BC, RN

Dementia, a syndrome of deterioration of cognition in alert persons that results in their impaired performance of activities of daily living, is difficult to recognize, especially in the early stages, and should be distinguished from delirium (Foster, n.d.). The importance of early recognition cannot be emphasized strongly enough because with early recognition and aggressive management, the outcome for reversible disease may be improved, and incurable dementias may be better managed (Feldman et al., 2008; Galvin & Sadowsky, 2012).

The cost of caring for persons with dementia is high: According to the Alzheimer’s Association, direct costs of Alzheimer’s disease in the United States in 2013 will cost the nation $203 billion and unpaid caregiver costs were estimated in 2012 to be valued at $216 billion.

Dementia and delirium were previously thought to be related, but now it is well established that these are, indeed, two separate disease entities. Delirium, also known as acute confusional state, is a transient disorder involving cognitive impairment with attentional deficit resulting in behavioral phenomena; like dementia, it is frequently misdiagnosed (Richards, 2009). Delirium is discussed in the second part of this chapter.

Dementia is distinguished from delirium because dementia is an acquired loss of or impairment in intellectual function whose nature is persistent and stable, whereas delirium is associated with altered consciousness, fluctuating deficits, and usually rapid onset (Richards, 2009). Because of the vast body of literature in this field, the references used for this article are mainly recent comprehensive review articles addressing the various subtopics presented here. The interested reader may wish to gather further, more detailed information from the references cited.

DEMENTIA

Dementia is an acquired loss of multiple cognitive functions and is usually, but not always, progressive, resulting in the deterioration of social, occupational, and functional abilities. At least two domains of intellectual function are affected: one is memory, and the other may be language, perception, visuospatial function, calculation, judgment, abstraction, or problem-solving skills. Patients may present with the full array of psychiatric symptoms (Richards, 2009).

ANATOMY, PHYSIOLOGY, AND PATHOLOGY

One useful scheme of classifying the dementias is by the structures involved, because each dementia is associated with a typical pattern of neuropsychological deficits correlated with specific brain sites (Tien et al., 1993). The three major categories of dementias are cortical, subcortical, and mixed (Table 48.1).

CORTICAL DEMENTIA

Cortical dementia affects predominantly the cerebral cortex and includes dementia of the Alzheimer’s type (DAT) and Pick’s disease. The clinical correlates include agnosia, apraxia, aphasia, amnesia, abnormal cognition, and abnormal affect (classically, depression); the motor system is unaffected (Koziol, Watt, & Budding, 2012).

Pathological studies of brains of patients with DAT reveal diffuse atrophy of the brain, with widespread loss of neurons, especially in the temporal, parietal, and anterior frontal lobe cortices. The degree of atrophy tends to correspond to the clinical stage of DAT. Microscopic studies show neurofibrillary tangles, senile plaques, and granulovacuolar degeneration, usually in the pyramidal neurons of the hippocampus. A definitive diagnosis can be made only at autopsy or on cerebral biopsy Koziol et al. (2012).

In Pick’s disease, which is less common than DAT, cortical lobar atrophy is highly focal, usually affecting the frontal and temporal lobes. Histopathological studies reveal intracytoplasmic Pick bodies (composed of neural filaments and tubules) and neuronal loss accompanied by cortical and subcortical gliosis (Barrett, 2012).

TABLE 48.1

Dementia Processes by Site of Involvement

Cortical dementia

DAT Pick’s disease

Subcortical dementia

Parkinson’s disease

Parkinsonian syndromes

Progressive supranuclear palsy

Olivopontocerebellar degeneration

Striatonigral degeneration

Multiple system atrophy

Huntington’s disease

Wilson’s disease

Hydrocephalus

Multiple sclerosis

HIV encephalopathy

Combined cortical and subcortical dementia

Vascular dementia (e.g., multi-infarct dementia, Binswanger’s disease, cerebral lacunae)

Infectious dementias (e.g., Creutzfeldt–Jakob disease)

Hypoxic encephalopathy

Miscellaneous (e.g., toxic and metabolic encephalopathy, posttraumatic events, neoplastic conditions)

DAT, dementia of the Alzheimer’s type.
Source: Tien, Felsberg, Ferris, and Osumi (1993).

SUBCORTICAL DEMENTIA

Subcortical dementia is caused by diseases that produce dysfunction in the basal ganglia, thalamus, and brainstem. It includes extrapyramidal syndromes, hydrocephalus, and white-matter disease. Clinical manifestations include not only forgetfulness, slowing of cognition, and abnormal affect (classically, depression), but also motor symptoms such as disorders of posture, increased tone with tremors or dystonia, and gait disturbance (Koziol et al., 2012).

Parkinson’s Disease

Dementia is identified in patients with Parkinson’s disease, a disease that affects approximately 1% of the population older than 50 years. Subcortical dementia of this type is associated with a reduction of pigmented cells of the substantia nigra, which results in malfunction of the efferent nigrostriatal tract; this loss of nigral input to the striatal dopamine receptors further results in disruption of normal coordination of basal ganglionic activity. The interruption of dopaminergic pathways from the ventral tegmentum to the frontal lobe may cause the clinically identifiable cognitive abnormalities. The remaining neuronal cells may contain eosinophilic cytoplasmic inclusions called Lewy bodies (Aarsland, Ehrt, & Rektorova, 2011; Libow, 2007).

Other Subcortical Dementias

Huntington’s disease, Wilson’s disease, hydrocephalus, multiple sclerosis, and HIV encephalopathy are also considered underlying causes of subcortical dementias.

The pathological changes associated with Huntington’s disease are gross atrophy of the head of the caudate nucleus, with less severe changes in the putamen and globus pallidus. Histologically, neuronal loss and gliosis in the caudate nucleus, putamen, and globus pallidus can be observed (Koziol et al., 2012).

Wilson’s disease (hepatolenticular degeneration), resulting from a genetic inability to synthesize ceruloplasmin, is associated with pathological evidence of atrophy, gliosis, edema, and occasionally necrosis in the lentiform nuclei (globus pallidus and putamen; Koziol et al., 2012).

Hydrocephalus is an uncommon cause of dementia, and can be corrected with resultant reversal of intellectual deficits. Dilation of the ventricular system is the main pathological feature (Koziol et al., 2012).

Multiple sclerosis is associated with multiple scattered lesions (plaques) involving the white matter—especially subependymal veins in the periventricular white matter, although the distribution of the plaques in the white matter could be random—but not the subcortical U fibers, cortex, and deep gray matter.

HIV encephalopathy is the most common infection-related dementia and the most common cause of dementia in young adults (excluding trauma). It is associated with multinucleated giant cells in the white matter and, to a lesser extent, the gray matter. Demyelination can be seen on neuroimaging (Koziol et al., 2012).

MIXED DEMENTIA

Mixed dementia includes conditions involving both cortical and subcortical structures; vascular dementia and infectious dementia are included in this category.

Vascular Dementia

Vascular dementia, the second most common form of dementia following Alzheimer’s dementia, includes syndromes of mental insufficiency related to multiple infarcts, small single strategically placed infarcts, posthemorrhagic states, and ischemic states not necessarily resulting in infarction. The vessels involved determine the signs and symptoms. Multi-infarct dementia, subcortical arteriosclerotic encephalopathy or Binswanger’s disease, and cerebral lacunae are the main vascular dementia syndromes (Alagiakrishnan, 2012).

In the brains of patients with Binswanger’s disease, demyelination, axonal loss, and hyalinoid thickening of small artery walls in the deep white matter can be observed (Alagiakrishnan, 2012). Cerebral lacunae result from small-vessel occlusions within the brain parenchyma (which show arterial disorganization and fibrinoid destruction), and refer to the presence of multiple small, deep, focal infarcts in the deep gray matter and internal capsule, suggesting wide-spread vessel disease (Alagiakrishnan, 2012).

Creutzfeldt–Jakob Disease

In Creutzfeldt–Jakob disease, there is diffuse cerebral atrophy with no evidence of inflammation. Neuronal loss and gliosis are widespread, accompanied by spongiform change (Koziol et al., 2012).

Dementia with Lewy Bodies

Recently, another category of dementia has been recognized: dementia with Lewy bodies. Neuropathologic autopsy examinations report that those with Lewy body dementia have Lewy bodies in their brainstem and cortex. Lewy body dementia accounts for about 10% to 20% of the pathologic subgroup among the dementias (after Alzheimer’s disease). Patients who have dementia with Lewy bodies tend to have progressive clinical symptoms, especially attentional impairments, problem-solving difficulties, and visuospatial impairments. Persistent visual hallucinations and spontaneous motor features of parkinsonism are hallmarks of the early development of this disease (Crystal, 2013).

The identification of the specific cause of dementia is important in improving both the treatment and the prognosis of the patient.

Epidemiology

The Alzheimer’s Association estimated that approximately 5.4 million Americans suffered from Alzheimer’s disease in 2012. The prevalence increases with age, as 5.2 million people older than 65 years have Alzheimer’s disease and approximately 200,000 individuals younger than 65 years have younger-onset Alzheimer’s disease. Thirteen percent of individuals older than 65 years have Alzheimer’s disease and approximately 50% of individuals older than 85 years have Alzheimer’s disease (Alzheimer’s Association, 2006, 2014; Hebert, Scherr, Bienias, Bennett, & Evans, 2003).

Diagnostic Criteria

Diagnostic criteria can be found in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5, American Psychiatric Association, 2013).

Risk factors for Alzheimer’s disease include those that are definite, such as old age, Down’ syndrome, family history, and ApoE genotype 4; those that are less definite, such as female gender, history of head injury, Down syndrome in the family, and vascular risk factors; and those that are least definite, such as aluminum intake and herpes simplex virus I infection (Alvarez, 2012; Donix, Small, & Bookheimer, 2012; Small, 2014).

History

Advanced age and a family history of DAT are the most important risk factors for Alzheimer’s disease; however, a family history of Down syndrome and hematologic malignancies (e.g., leukemia, myelolymphoma, and Hodgkin’s disease) is also important. Although familial predisposition appears to be a risk factor for vascular dementia, the association is not as strong with DAT. As would be expected, family history is extremely important in hereditary dementias such as Huntington’s disease, Wilson’s disease, and metachromatic leukodystrophy.

Suspicion of dementia related to head trauma should be raised in patients with a history of severe head trauma or multiple traumas acquired over a period of time. Suspicion of neurosyphilis should be raised if the patient has had an untreated or partially treated sexually transmitted disease; similarly, acquired immunodeficiency syndrome (AIDS)–dementia complex should be suspected if the patient has risk factors for HIV (e.g., homosexuality, multiple sex partners, intravenous drug use).

A history of chronic medical illnesses such as epilepsy, renal failure, or hepatic cirrhosis, especially if poorly controlled, as well as a history of occupational exposure to heavy metals or other toxins, should also raise the index of suspicion for dementia (Richards, 2009).

As mentioned earlier, a history of the clinical pattern of the disease may provide clues as to whether the dementia is of a degenerative or vascular type. The former tends to progress insidiously and slowly, whereas the latter tends to occur in a stepwise fashion (probably coinciding with cerebrovascular events). Interviews of family members often yield additional information regarding the patient’s deteriorating memory, changes in language skills, and functional impairment, if any, providing more clues that could aid in pinpointing the diagnosis (Richards, 2009).

Early signs of dementias include problems with the performance of personal care tasks, changes in personality (e.g., indifference, regression, impulsiveness, withdrawal), and behavioral changes (e.g., agitation, aggression, restlessness, wandering, delusions, paranoia, hallucinations, and sleep-cycle disturbances; Richards, 2009).

PHYSICAL EXAMINATION AND LABORATORY STUDIES

A thorough physical examination may disclose evidence of a systemic disease to which dementia or the risk thereof may be associated. Examples include enlarged liver and hepatic encephalopathy, Kaposi sarcoma, and focal neurologic findings (e.g., asymmetrical hyperreflexia or weakness, seen more often in vascular dementia than in degenerative diseases; Richards, 2009).

Neurologic and psychiatric histories should also be taken and tests performed, but a diagnosis should be reserved until results from several tests or questionnaires have been obtained and correlations can be made with results of the physical examination (Andreasen & Black, 2010; Scott & Barrett, 2007). Neurologic examinations should include mental status testing, brief screening tests, and formal cognitive testing (e.g., 30-point Mini-Mental State Examination—a score of 25 or less suggests impairment; a score of 20 or less usually indicates definite impairment [Andreasen & Black, 2010]).

Table 48.2 reviews some of the abnormalities that may be present on an elementary neurologic examination and their possible causes (Sandson & Price, 1996). Psychiatric evaluation should take into consideration that depression and dementia, both of which are common in elderly patients, may coexist, especially in the early stages of degenerative dementias; pseudodementia (reversible dementia resulting from depression) should be ruled out (Table 48.3). In these cases, neuropsychological evaluation may be helpful to distinguish depression from dementia. DAT is associated with withdrawal, paranoia, and anxiety; depression, delusions, and “emotional incontinence” are common in patients with vascular dementias; and personality changes, disinhibited behaviors, social withdrawal, and lack of insight are associated with Pick’s disease (Scott & Barrett, 2007).

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