Mohammed T. Abou-Saleh

118 PRINCIPLES AND PRACTICE OF GERIATRIC PSYCHIATRYThe following discussion reviews each of the DSM-IV axes,considering aging-specific topics. They point to areas of controversythat will need further study before inclusion in a futureDSM-V. As well, they will highlight planned alterations for theforthcoming text revision of DSM-IV (‘‘DSM-IV-TR’’) withregard to the diagnosis and classification of neurodegenerativeprocesses, such as Alzheimer’s disease.Axis IDSM-III and DSM-III-R continued the tradition of distinguishingbetween ‘‘organic’’ and ‘‘functional’’ disorders. Thisconceptual typology had posited a difficult-to-maintain dichotomy,one that was poorly justified in light of modern research 2 .Aswell, ‘‘organic’’ diagnoses too often had been applied without anyclear rationale. Instead, DSM-IV emphasizes a conceptual moveaway from concerns about the presence of structural pathology,or its absence, to a consideration of etiologic link.It is more meaningful, both clinically and heuristically, to labela disorder as ‘‘primary’’ (i.e. idiopathic) when its cause isunknown, rather than using a term such as ‘‘functional’’ thatimplies a specific type of physiological or psychological mechanism.‘‘Organic’’ arose in the nineteenth century after the detectionof organ (i.e. brain) pathology. Research findings of the past 30years have clouded any hope of using such a criterion forseparating alleged psychological from alleged biological disturbances.DSM-IV expects clinicians to clarify whether a disorder isprimary (i.e. idiopathic) or ‘‘secondary’’ or ‘‘symptomatic’’. (Thetext itself avoids using the latter designations, given controversy inthe USA regarding their exact definitions.) A lengthy descriptionis provided in DSM-IV to help clinicians reason whether there issufficient evidence to attribute the etiology of a psychiatricsyndrome to a definable disease process. Thus, one mightdiagnose ‘‘mood disorder due to Parkinson’s disease’’ or‘‘psychotic disorder due to Huntington’s disease’’ where there isa decision that the psychopathology is a direct reflection of thefundamental pathophysiological process that causes Parkinson’sdisease or Huntington’s disease.While DSM-IV includes a chapter describing symptomaticpsychiatric conditions, they are distributed throughout the text,grouped with the primary psychiatric disorders with which theyshare phenomenological features, forcing clinicians to considerdifferential diagnostic questions directly. Although the impact ofthis change extends beyond older patients, it has frequentapplication to elders, given their heightened rates of generalmedical conditions. Whether geriatric psychiatrists and otherclinicians have, in fact, undertaken a more rigorous approach toconsidering etiological relationships because of the changes inDSM-IV remains to be defined.Cognitive DisordersDelirium, dementia and amnestic disorders were clusteredtogether in DSM-IV as ‘‘cognitive disorders’’. DSM-III-Rdeveloped, perhaps inadvertently, very restrictive criteria fordelirium that excluded a variety of patients whose clinicians werecertain about the diagnosis, but unable to use the diagnostic label.Beyond traditional definitions employing attentional dysfunctionand fluctuating consciousness, DSM-III-R required the presenceof ‘‘disorganized thinking’’, as evidenced by formal thoughtdisturbance. However, mildly delirious patients may not haverambling, irrelevant or incoherent speech. DSM-IV returned to abroader view.While the successive editions of the DSM have been the primaryclassification for American psychiatry, ICD-9-CM (InternationalClassification of Diseases, 9th edn, Clinical Modification) has beenadopted by international treaty as the medical diagnostic codingsystem used by the US Government for all data collection andreporting regarding morbidity and mortality. In order to receivereimbursement from Medicare, for example, every clinician mustreport diagnoses in terms of ICD-9-CM codes. These range from00–0999, and are organized in sections based upon the type ofdisease process (e.g. infectious and parasitic diseases, 001–139;neoplasms, 140–239), anatomic location (e.g. diseases of thedigestive system, 520–579; diseases of the nervous system andsense organs, 320–389) or functional area (e.g. mental disorders,290–319).The entire system of diagnostic coding now is being revampedduring the development of ICD-10-CM. This is intended to dealwith the problem of ‘‘double coding’’ (e.g. diagnosing meningitisas both an infection and a disease of the nervous system) andother shortcomings, most notably an insufficient number ofpotentially available codes for future classification needs. Beginningwith the completion of ICD-10 by the World HealthOrganization during the early 1990s, the most important changehas been the adoption of an alpha-numeric coding system, inwhich letters are used to indicate the section of the ICDclassification from which the code is drawn. Thus, infectiousdisease codes start with the letter A, neoplasms start with theletter B, etc. Codes formerly contained in the Mental Disorderssection (290–309) will start with the letter F, while codes formerlycontained in the Diseases of the Nervous System (320–389) will beincluded under the letter G. The ‘‘clinical modification’’ of ICD-10 currently being developed by the US National Center forHealth Statistics, using this alpha-numeric system, will be adoptedofficially within the next several years. The most significant changefor geriatric psychiatry will be the provision in ICD-10-CM ofonly one code for Alzheimer’s disease, G30, instead of the doublecoding that was part of DSM-IV and ICD-9-CM. Althoughsufficiently similar to ICD-10 to allow cross-national comparisonof health data, ICD-10-CM will have several significant differencesin terminology and level of specificity.Subtypes of dementia of the Alzheimer type (DAT) andvascular dementia (i.e. with delirium, with depressed mood, andwith delusions) were first introduced into the DSM-III at a timewhen these categories were referred to as ‘‘primary degenerativedementia’’ and ‘‘multi-infarct dementia’’. These subtypes werelater carried forward into DSM-III-R and DSM-IV. Theexpressed rationale for adding these subtypes had been parsimonyof diagnosis, based on the assumption that these three conditionswere fundamental manifestations of dementia. It did not makesense to require a clinician to use an additional diagnosis todescribe what were considered to be aspects of the primary clinicalcondition. But neither DSM-III nor DSM-III-R provided explicitinstructions about when to use specific subtypes, and a number ofquestions arose regarding their use. For example, did ‘‘withdepressed mood’’ include full-blown major depressive episodesoccurring during the course of Alzheimer’s disease, or just milderforms of depression? Should ‘‘with delirium’’ include all forms ofsuperimposed delirium, or just delirium thought to be directly dueto Alzheimer’s disease or vascular pathology? How should onediagnose delirium secondary to suspected drug toxicity in ademented patient? What should be one’s approach to describingother commonly encountered symptoms or signs, e.g. delusions,hallucinations, agitation, or anxiety? When delirium, delusionsand depressed mood occur simultaneously, which diagnostic codedoes one choose?DSM-IV continued to use this subtyping with three changes.A new subtype, ‘‘with behavioral disturbances’’, was added inorder to allow the user to indicate ‘‘clinically significantbehavioral changes (e.g. wandering)’’, although this was notcodable in any numeric fashion. The ‘‘with delusions’’ subtype