Mohammed T. Abou-Saleh

522 PRINCIPLES AND PRACTICE OF GERIATRIC PSYCHIATRYTable 95.2the elderlyacute events, such as myocardial infarctions, strokes, transientischemic attacks; and exacerbation of chronic conditions, such aschronic obstructive pulmonary disease. Furthermore, medicationsare frequently part of, if not the underlying etiological cause of,delirium. Medications may contribute as a result of their sideeffectsprofile, toxicity or mechanism of action. Inquiries shouldbe made about the use of other substances, including alcohol orillegal drugs. Corticosteroids, digoxin, anticholinergic drugs anddopaminergic agents are just some of the medications that may beimplicated.The elderly are very sensitive to the side effects of medications,especially to the anticholinergic side effects of drugs. Manymedications have anticholinergic side effects, including manyantipsychotics, both typical and atypical. The untoward peripheralanticholinergic effects of dry mouth, constipation, urinaryretention and dry eyes are troublesome to the elderly and mayfurther aggravate pre-existing physical conditions. Untowardcentral effects of these medications include the worsening ofconfusion and cognitive functioning.TREATMENT OF PSYCHOSISDifferential diagnosis of psychotic disorders inMedical conditionsInfectionsUrinary tract infectionsPneumoniaViralElectrolyte imbalanceEndocrine disordersCardiovascular eventsMyocardial infarctionsArrhythmiasNeurologicalTransient ischemic attacksSeizuresStrokesNeoplasmsOther eventsUrinary retentionImpactionOne should keep in mind when treating the elderly the old axiomof ‘‘do no harm’’. The risk:benefit ratio of all treatmentsprescribed to elderly patients must always be assessed. Whenchoosing an antipsychotic, one should take into account treatmenthistory and susceptibility to potential side effects, as well asfamily history and familial response to medications. An importantprinciple to apply when initiating treatment is to ‘‘start low and goslow’’. Treatment should be initiated with doses of half to onethirdadult starting dose, remembering that most elderly patientswith psychotic symptoms require much lower doses than youngerpatients.Age-related bodily changes affect the pharmacokinetics ofneuroleptics in the elderly. Absorption of medications may bealtered by changes in gastric acidity and emptying and changes inblood flow. Age changes the body’s composition, causing anincrease in body fat with an associated decrease in lean body massand total body water. In addition, there are decreases in liver massand blood flow and changes in renal blood flow and function. Allthese changes affect the absorption, metabolism, distribution andclearance of neuroleptics.The phenothiazides are lipophilic substances, well absorbed,with an extensive first-pass metabolism in the liver. In the elderly,as a result of the increase in total body fat, there is an increase inthe volume of distribution of drugs. This leads to an increasedhalf-life for those substances that are lipophilic. Thus, the elderlyshould be given lower doses of lipophilic drugs.Neuroleptics are the treatment of choice for psychosis. Theyhave recently been divided into typical (conventional) and atypicalantipsychotics, based on their capacity to treat the positive andnegative symptoms of schizophrenia as well as their potential tocause neurological side effects. All antipsychotics have the samelevel of efficacy. It may be relevant to recall that 100 mgchlorpromazine is equivalent to 1 mg haloperidol and 0.5 mgrisperidone.Typical or ‘‘conventional’’ antipsychotics can be divided intogroups, based on their potency—high, intermediate and lowpotency. High-potency antipsychotics include haloperidol, fluphenazineand loxapine. High-potency neuroleptics have greateraffinity for the dopamine receptors and less affinity for themuscarinic and a-receptors. High-potency neuroleptics are morelikely to be associated with a higher incidence of extrapyramidalsymptoms, akathisia, acute dyskinesia and parkinsonism, thuslimiting their use in the elderly. Intermediate potency neurolepticsinclude perphenazine, loxapine and molidone. The atypicalneuroleptics are clozapine, risperidone, olanzapine, quetiapineand ziprasidone. Low-potency antipsychotics, such as thioridazineand chlorpromazine, have a higher affinity for muscarinic,histaminic and a-adrenergic receptors and furthermore are morelikely to produce increased sedation, orthostatic hypotension andanticholinergic side effects. They should be prescribed withcaution in the elderly.Limitations of Typical Neuroleptics in GeriatricsTypical antipsychotics block various receptors that have thepotential to cause side effects which can limit their use in theelderly. Dopaminergic blockade is associated with acute and longtermneurological side effects. Acute neurological side effects areextrapyramidal side effects (EPS), which include parkinsonism(resting tremors, rigidity, bradykinesia and gait disturbances),akathisia and dystonias and long-term effects of tardive dyskinesia,as well as the potential for neuroleptic malignant syndrome(NMS). Histaminergic blockade is associated with sedation andweight gain. Their quinidine-like cardiac effects are associatedwith the potential for arrhythmias. a-Adrenergic blockade leads toorthostatic hypotension. In addition, the muscarinic blockadeleads to anticholinergic side effects.Neuroleptic induced parkinsonism (NIP) is a potential concernwith the use of neuroleptics in the elderly. The reported prevalenceof NIP in patients aged over 60 on neuroleptics is 50% 17 . Onestudy that looked at the use of low-dose neuroleptics and theincidence of NIP in the elderly found that 32% of patientsdeveloped NIP on an average daily dose of 43 mg chlorpromazine17 . In addition, the risk factors contributing to the incidence ofNIP were older age, instrumental tremor at baseline, EPS, thetype of neuroleptic administered and the severity of dementia 17,18 .Parkinsonism can increase the risk of dependency, falls andfractures 19 . These often troublesome side effects can be treatedeither by reducing the neuroleptic dose, switching to an atypicalagent, or using anticholinergics such as benztropine or trihexyphenidyl.Care needs to be taken when using antiparkinsonianmedications in the elderly, who are very sensitive to theanticholinergic side effects.Akathisia is another neuroleptic side effect that can be difficultto address. Akathisia is characterized by increased restlessnessand psychomotor activity, with an inability to sit still. Akathisia is