Birmes and associates. Drugs with dopaminergic activity used in the treatment of Parkinson disease are notorious for the induction of confusion or delirium, but it appears that the underlying disease provides an important substrate. Allied compounds with sympathomimetic actions such as cocaine and phencyclidine produce a hallucinatory delirium and yet others with different pharmacologic properties such as glutaminergic activity may result in a variety of delirious fragments or pure hallucinosis. Another entity that arises in this context is the neuroleptic malignant syndrome, a state associated with an agitated confusion followed by stupor. However, the characteristic features in neuroleptic malignant syndrome (NMS) are progressive muscle rigidity and evidence of myonecrosis as indicated by elevations of the serum creatine kinase; usually there is in addition some elevation of body temperature. The clinical examination and a thorough history aid greatly in determining which category of drug is implicated.
Dementing Disease Complicated by Confusional States and Delirium in the Elderly
Physicians are all too familiar with the situation of an elderly patient who enters the hospital with a medical or surgical illness or begins a prescribed course of medication and displays a newly acquired mental confusion. Presumably, the liability to this state is determined by preexisting brain disease, most often Alzheimer disease but sometimes Parkinson disease, multiple small deep cerebral infarctions, or another dementing process, which may or may not have been obvious to the family before. All the clinical features that one observes in the acute confusional states may be present, but their severity varies greatly. Confusion may be reflected only in the patient’s inability to relate the history of the illness sequentially, or it may be so severe that the patient is virtually non compos mentis. An analysis of other studies by Witlox and colleagues has estimated that the risk of dementia in persons over 85 years if an episode of global confusion has occurred is almost 9 times the rate in others of the same age. Authoritative writers have suggested that confusion is causal to subsequent dementia but evidence for this is so far lacking.
The family and even the primary physician often identify the problem as abrupt in onset and having no precedent as the patient seemingly functioned well previously. However, careful questioning about the patient’s independent capability in handling of finances and shopping, organization of household matters, driving, relating to neighbors or family, and even previous episodes of confusion to which the family paid little heed, are usually uncovered.
Although almost any complicating illness may bring out a confusional state in an elderly person, the most common are febrile infectious diseases; trauma, notably concussive brain injuries; surgical operations, general anesthesia and preand postoperative medication; even small amounts of pain or sedative medications used for any cause; and congestive heart failure, chronic respiratory disease, and severe anemia, especially pernicious anemia. With regard to medications, those even seemingly innocuous ones, may cause the syndrome (e.g., histamine blockers used to reduce gastric acid, anticonvulsants, corticosteroids, and l-dopa, and certain antibiotics). Often, a “multifactorial” etiology is implicated by physicians and writers in this field and poor eyesight and hearing are included in this ambiguous and unsatisfactory term, especially when moderately severe electrolyte imbalance or renal failure are added implicated in the mix of other factors. Admittedly, it is difficult to determine which of several possible factors is responsible for the patient’s confusion, and often there may be more than one. In a cardiac patient, for example, fever, hypoxia or hypercarbia, one or more drugs, and electrolyte imbalance each may contribute. For a perspective on the relative contributions to confusion in the elderly of various medical and pharmacologic factors, the reader may consult the review by Inouye and colleagues.