Mohammed T. Abou-Saleh

DRUG MISUSE 615considered benzodiazepine misuse by some and as elder abuse byothers 49 .complications may arise from the misuse of other medications, thecommonest being laxatives and cough mixtures.CorrelatesPsychiatric MorbiditySignificantly high rates of psychiatric disorder have beendescribed among elderly benzodiazepine users 50 . Among eldersusing short-acting benzodiazepines as hypnotics, one-third reachcaseness for depression, while a further one-third have adiagnosable anxiety disorder. Amongst users of anxiolyticbenzodiazepines, half are depressed and one-fifth are anxious inspite of treatment. These results are not evidence of a causativerelationship, although the most likely indications for initiation ofsuch medication by a prescriber are likely to be presentation withsuch symptoms. As with alcohol misusers, one-third of eldersrequiring inpatient treatment for benzodiazepine misuse are oflate onset, while two-thirds have graduated from misusingbenzodiazepines or other drugs whilst younger 51 . The incidenceof co-morbid alcohol abuse has not been consistently shown to besignificantly greater among benzodiazepine misusers 51,52 . An allagestudy found that DSM-III-R Axis I co-morbidity existed in allcases of a sample of benzodiazepine dependent users in Spain 53 .The commonest diagnoses were insomnia, anxiety disorders andaffective disorders. Obsessive–compulsive, histrionic and dependentpersonality disorders were found in half the cases andphysical problems in one-third of cases.Gender and AgeBenzodiazepine use is over-represented among women of all ages.The likelihood of use of a benzodiazepine increases with age.There is little evidence that this gender divide narrows on reachingold age. Legislative approaches and prescribing guidelines havemade some inroads into the over-representation of prescribing tothe elderly 53 . Increasing public awareness of the side effects ofbenzodiazepines and an increase in advocacy services for theelderly are likely to have a similar effect.ILLICIT DRUG MISUSELittle is known about levels of illicit drug use among the over-65s,although the general perception is that it has been less of aproblem than the misuse of prescribed medication. In theEpidemiological Catchment Area Study (ECA), only 0.1% ofelders met the criteria for drug abuse for an illicit substance in theprevious month 56 . Lifetime prevalence was 1.6% for over-65s.This may change as younger generations with a pattern ofrecreational drug use reach old age. In the UK, few cases of illicitdrug use among the over-65s have found their way into theliterature; one exception is a series of seven elderly reported tohave initiated injecting heroin in later life. They attributed theirbehaviour to a combination of loneliness and depression 57 . In theUSA, in a recent study of a Veterans’ Administration old agepsychiatry inpatient facility, 3% of the patients were found tohave a primary drug misuse disorder involving prescribedmedication, while 1% were addicted to illicit substances 58 . Alsoin the USA, attendance at methadone maintenance clinics by theelderly is reported to be rising, although over-60s still form 2% ofthose attending 59 . Similarly, a number of elders are reported tocontinue their use of cannabis into late life 47 . Anecdotal evidencealso points to some individuals initiating the use of cannabis inlater life in a search for its reputed therapeutic benefit inconditions such as disseminated sclerosis.On balance, it appears that illicit drug use is less of a problem inthe elderly than the abuse of legally sanctioned drugs. It remainsto be seen whether individuals currently abusing illicit substancesin younger age groups carry this behaviour over into old age. Thenature of the subject has not lent itself to prospective studies asyet. One might expect greater levels of illicit drug use in futuregenerations of older adults, although difficulties associated withobtaining a supply of such drugs with increasing infirmity arelikely to account for some cessation in use. It is also tempting tospeculate that those abusing illicit drugs as younger adults mayswitch to misusing prescribed medication in later life.Other Prescribed and Over-the-counter MedicationAs indicated earlier, the elderly routinely receive a wide variety ofmedications, the majority of which may be misused. A quarter tohalf of the elderly experience chronic pain. In acute use thedependency potential of analgesics is believed to be around 0.1%.In chronic conditions the situation is somewhat different. Ten percent of over-64s are on prescribed analgesics at any one time, withat least an equal number using over-the-counter medication.Edwards and Salib 54 found 3% of a community sample of over-65s to have been using mild opiate analgesics for a period of atleast 1 year; 40% of this group were deemed to fulfil the criteriafor dependence upon these drugs, with dependence levels as highas two-thirds among users of co-proxamol.In addition to the dependence caused by these drugs, physicalharm may also result, e.g. nephropathy may be caused by the useof paracetamol, salicylates and pyrazole derivatives, while renalimpairment occurs with non-steroidal anti-inflammatory druguse 55 . Chronic nephropathy may also be caused by the excessiveingestion of analgesic mixtures combining two or more antipyreticanalgesics, along with codeine or caffeine (both independentlycapable of causing addiction). Such acute and chroniceffects are more likely amongst the elderly, where relative druglevels are higher and less biological reserve exists. Similar physicalPOLYSUBSTANCE MISUSEThe elderly have access to a variety of drugs of misuse. In manycases they may misuse one drug without misusing others. This isoften the case with prescribed medication, where one medicationis overused while compliance with the prescription is maintainedfor the others. Where non-prescribed substances become involved,the possibility of abuse of more than one substance is elevated.Finlayson 50 found 15% of over-65s requiring inpatient detoxificationfrom alcohol were also dependent upon a second substance,usually a hypnotic, anxiolytic or analgesic.The phenomenon of cross-tolerance must also be considered.Psychoactive substances may have a cumulative effect, due toeither a shared outcome effect or to different drugs acting asinterchangeable substitutes for one another (cross-tolerance).Cross-tolerance exists within each class of drug, such that theclinician should always consider the total benzodiazepine,barbiturate or opioid dose, using class-specific equivalencecharts 60 . Cross-tolerance for some drugs may also occur outsideof the class, most notably for alcohol, chlormethiazole andbenzodiazepines. While this phenomenon is widely exploited fordetoxification, failure to consider the possibility of its existencemay lead to overlooking cases of dependence.