Illusions and Delusions- Part II-Dementia and Delirium
Dementia refers to a group of disorders characterized by progressive loss of cognitive functions. It is more than forgetting or age related changes in memory. A cascade of events has to occur in the brain for dementia to be evidenced in behavior.Some dementia is temporary. Irreversible dementia can be divided into four categories of origin: degenerative diseases; vascular diseases; traumatic dementia and infections. Alzheimer’s disease, Lewy body dementia and vascular dementia account for most cases of dementia (See below for a full list of diseases that may cause dementia.) Progression of the dementia associated with these diseases invariably leads to increasing dependence on others for everyday care as well as increasing health costs. Medicare, except in extraordinary circumstances, does not pay for long term custodial care for dementia.(See Medicare articles). Residents of nursing homes usually have to spend down their savings before being covered by Medicaid.
In its initial stage, dementia is characterized by some degree and quality of change in behavior and cognition, and not by any presence of specific histological changes that are measurable. It is hard to diagnose in this initial phase. To date, there are no biological tests for dementia itself. In many cases, those around the patient are aware of subtle changes in behavior and memory. Sometimes the individual is aware of cognitive changes, but does not attribute it to dementia. At the same time, individuals worry about "forgetting" and have anxious moments filled with thoughts about becoming demented. An individual's anxiety over this issue can be debilitating in of itself. Neuropsychological tests may pick up early signs of possible dementia before they express themselves.
Psychotic features associated with dementia involve altered perceptions, which may include hallucinations, misperceptions and delusions. Hallucinations, when present, are most commonly visual (actually see things that are not there as opposed to thought broadcasting or thought insertion). Typical misperceptions include inability to recognize oneself in a mirror and an inability to distinguish a real person from a TV image. Delusions are most commonly paranoid and relate to the ideas of theft, abandonment or infidelity.
The clinical features of dementia often point to a specific cause. In patients with Alzheimer’s disease, memory loss, language impairment and visuospatial disturbances (distance as well as place is misjudged; also not sure where they are) are typical. Often these patients appear indifferent and experience delusions and agitation especially during advanced stages.
Frontotemporal dementia e.g. Pick’s disease, by contrast, evidences marked personality changes and executive dysfunction (difficulty in higher order capabilities that are called upon in order to formulate new plans of action and to select, schedule and monitor appropriate sequence of action) but a relative preservation of visuospatial skills.
Patients with dementia called Lewy body type display symptoms such as tremors, stiffness, or some signs of Parkinson disease. They may experience visual hallucinations, delusions, fluctuating mental status and evidence a high degree of sensitivity to neuroleptic medications.
The depression symptoms associated with Alzheimer's disease tend to be indirect, taking the form of agitation and insomnia. This contrasts with depression as a primary diagnosis, where the patient exaggerates cognitive deficits and appears poorly motivated. Such patients also emphasize mood complaints, while language and motor skills remain in tact. Here is where diagnosis proves important. Specialists is geriatric medicine should be consulted along with a neuropsychological evaluation to distinguish depression from Alzheimer’s Disease.
VASCULAR DEMENTIA
The main focus of therapy in vascular dementia is prevention. It has been argued that once a patient fulfills the criterion for dementia, it is too late to do anything. Improved control of hypertension and cessation of smoking reduce the risk of developing vascular dementia.
Determining the prevalence of vascular dementia is problematic. Lack of agreement on the definition of this disorder has resulted in widely varying prevalence rates. One problem is that vascular dementia is a syndrome with multiple causes and multiple manifestations. There is a great deal of controversy regarding the relationship between vascular brain injury and dementia. It is unclear what size, type and the number of lesions, and in what location, will cause dementia. Many vascular lesions have been seen using computerized tomography (CT) or magnetic resonance imagery (MRI) in people with normal cognition.
Is vascular dementia primarily a dementia, or a vascular disease, which can be treated? Is it a consequence or a special form of cerebrovascular disease, or do patient’s who are going to develop it need to have some additional degenerative changes in order to become demented? These are things that are not very clear at this time.
The diagnosis of vascular dementia depends on the criteria selected and on the presumed pathophysiology and symptoms that can be detected and recognized in a particular patient. If a patient is demented, and if there are clear signs and symptoms of cerebrovascular disease (stroke), and if the dementia follows shortly after the cerebrovascular events, the diagnosis of vascular dementia is probably clear.
ALZHEIMER’S DISEASE
Alzheimer’s disease causes a devastating loss of cognitive and functional capacities. It is estimated that more than 4 million people in the US currently suffer from AD. At some point in time virtually all persons with AD will require continuous care. The psychological and financial burdens are devastating to everyone involved with an AD patient.
In many ways, taking care of patients with AD is different from assisting patients with only physical ailments. For example, patients with AD have impaired insight, often misjudging or denying the extent of their physical and mental impairment. These patients may perceive the intervention of a caregiver who assists them with performing the activities of daily life (ADL) as an indignity and, mistakenly, as an imposition. Consequently, patients with AD frequently display behaviors that are disturbing to the caregiver and disruptive to the caregiving process. These include resistance, rejection, agitation, negativism, and verbal or physical aggressiveness and abuse. These behavioral changes are, at least in part, accompanied by changes in neuromotor function. With the progression of the disease, the brain is increasingly less capable of selecting and modifying its responses to various incoming stimuli. Consequently, the body of a patient with AD reacts differently to a variety of external stimuli that act upon it compared to the body of a healthy person. These fundamental changes in neuromotor function profoundly complicate patient care because they limit the patient’s physical capability to cooperate with the caregiver.
AD is characterized in the brain by the deposition of amyloid protein outside the neuron, resulting in the formation of plaques and inside the neuron with neurofibrillary tangles, which are cytoskeletal components that affect the way the neuron functions. The number of synapses is decreased in AD. The synapse is the unit of communication between cells. Loss of synapses is reflected in dementia. This loss occurs across a number of different kinds of neurons that make different kinds of neurotransmitters, but not in all areas of the brain or across all neurons. They are most seen in temporal and parietal regions with extension to frontal cortex of the brain. The neurotransmitters, which are most often affected, are those known to be involved in the learning and memory processes. Acetylcholine is eventually diminished in virtually all patients with AD. There is a deficiency in CSF immunoreactivity and somatostatin immunoreactivity. The assumption made is that the cells that make these neuropeptides are dysfunctional and are losing synapses as well.
Diagnosis is generated by a history of progressive deterioration over some period of time in at least two domains of cognition, of which one is usually memory. Apolipoprotein E genotyping is not considered diagnostic for AD. In 5% of all the Alzheimer’s disease cases, a chromosome deficiency has been found. This is called early-onset Alzheimer’s disease and manifests itself before the age of 65. The vast majority of AD appears to be sporadic and involve a process not fully understood to date, with the amyloid precursor protein playing some important role. (See below.)
Non-cognitive symptoms associated with AD, such as agitation, paranoia, uncooperativeness and depression can be treated. This makes for a better quality of life for the patient, though it is not a cure for Alzheimer’s disease. Psychoactive agents with anticholinergic effects and benzodiazepines should not be used because they can worsen cognition. (See our series of articles on AD listed below).
A number of potential therapies are currently under investigation including estrogen replacement, anti-inflammatory agents, free radical scavengers and antioxidants, and monoamine oxidase-B9 (MAO-B) inhibitors. (For a list of drug companies doing research in this area see articles under Alzheimer’s disease on this web site) In addition, other approaches, such as anti-amyloid treatments that affect beta-amylase secretion, aggregation and toxicity, appear promising; treatments that hinder neurofibrillary tangle construction and nerve growth factor (NGF) induction are in the early stages of development.
In AD, progressive loss of cognitive abilities usually begins with difficulties in episodic memory (refers to the ability to remember personally experienced events such as what you had for breakfast the previous day) and soon encompassing language, visuospatial and executive dysfunction. The classical pathological features include neurofibrillary tangles, amyloid plaques and neuronal and synaptic loss.
Risk factors for developing AD include advancing age, family history of dementia, substandard education, a history of head injury and a history of smoking. Lower risk has been reported with a history of arthritis, use of NSAID’s and use of estrogen replacement in postmenopausal women.
Researchers are still trying to understand the disease process. Three genes have been identified; beta amyloid precursor protein (b -APP) and two presenilin proteins (PS1 & PS2) that cause early-onset AD (before 65 years), whereas apolipoprotein E (ApoE) epsilon 4 has been identified as a susceptibility gene for late onset disease. Other events have to occur for it to evidence penetration (Swartz RH, Black SE, St. George-Hyslop P. Apolipoprotein E and AD: a genetic, molecular and neuroimagery review. Canadian Journal of Neurological Sciences 1999; 26:77-88)
LEWY BODIES
Lewy bodies are found in the substantia nigra of patient’s with Parkinson’s disease (in the neocortex, limbic structures, and brain stem of patients with Parkinson’s disease and dementia). They are also found in association with the neuropathologic features of Alzheimer’s disease in the neocortex, limbic structures and brain stem of patients with dementia and varying features of Parkinson’s disease referred to as the Lewy body variant of Alzheimer’s disease.
The clinical criteria for diagnosis of Lewy body type are:
(A) fluctuating cognitive impairment;
(B) at least one of the following: visual or auditory hallucinations usually accompanied by delusions; mild extrapyramidal side effects of sensitivity to neuroleptic drugs; or repeated unexplained falls, transient clouding, or loss of consciousness;
(C) rapid progression to severe dementia compared to the clinical finding of Alzheimer’s disease.
The lower cerebral spinal fluid levels of homovanillic acid were significant in the Lewy body patients. This reduced metabolism of dopamine may be related in part to the presence of the Lewy bodies in the mesolimbic and mesocortical areas, and may correlate to the higher frequency of psychotic symptoms.
To read more, go to yesterdays post and click on the part 2 link
