Mohammed T. Abou-Saleh

114 PRINCIPLES AND PRACTICE OF GERIATRIC PSYCHIATRYallow the recording of an unusually early or late onset of thedisorder. In other words, the mental disorders occurring in theelderly are no longer considered to belong in a separate categoryof morbidity. This is very much in line with research conducted inthe past two decades, which has demonstrated that the relativelyhigh prevalence of mental morbidity in the elderly in Westerncultures is related to a wide range of psychosocial factors (e.g.social isolation, cultural uprooting and institutionalization), aswell as to physical co-morbidity, but that the aging process itselfdoes not produce nosologically specific forms of disorders.If section F0 of ICD-10 is used as a diagnostic decision tree,there is a choice of five entry points at the level of clinicalsyndrome: (i) dementia; (ii) amnesic syndrome; (iii) delirium; (iv)organic quasi-functional disorder (affective, delusional, hallucinatoryor other); and (v) personality or behavioural disorder.Once a disorder is identified at this general syndrome level, thenext step is defined by the diagnostic guidelines, which lead intomore specific diagnostic categories. The diagnostic decision rulesfor dementia illustrate the point.The syndrome of dementia is defined in ICD-10 by ‘‘evidence ofa decline in both memory and thinking, which is of a degreesufficient to impair functioning in daily living’’, in a setting ofclear consciousness. For a confident diagnosis to be established,such disturbances should have been present for at least 6 months.Deterioration of emotional control, social behaviour and motivationrepresent significant additional features but the overridingcriterion is the presence of memory, learning and reasoningdecline. The ICD-10-DCR (research criteria) add anchor pointsfor a grading of the deficits into mild, moderate and severe,separately for memory and intellectual capacity. The overallgrading of the severity of dementia is made on the basis of thefunction which is more severely impaired.Once the presence of the syndrome of dementia is established,the diagnostic process branches off into the different clinicalvarieties of dementia typical of Alzheimer’s disease, vasculardementia and dementia in diseases classified elsewhere (includingPick’s disease, Creutzfeldt–Jakob disease, Huntington’s disease,Parkinson’s disease, HIV disease and a range of systemic andinfectious diseases, such as hepatolenticular degeneration, lupuserythematosus, trypanosomiasis and general paresis). Dementia inAlzheimer’s disease is subdivided into Type 1 (onset after the ageof 65) and Type 2 (onset before the age of 65). Although the ICD-10-DCR criteria emphasize the ultimate criterion of the neuropathologicalexamination and the supporting role of brainimaging, they nevertheless allow for a confident clinical diagnosisto be made if clear evidence of a memory and intellectualperformance deterioration has been present for 6 months or more.The ICD-10 criteria for vascular dementia are broader than thecorresponding DSM-IV criteria: they include not only multiinfarct(predominantly cortical) vascular dementia but also thesubcortical dementias (Binswanger’s encephalopathy being anexample), as well as the mixed cortical and subcortical forms.As regards the diagnosis of delirium, ICD-10 has abandonedthe distinction between acute and subacute deliria; the condition isdefined as ‘‘a unitary syndrome of variable duration and degree ofseverity ranging from mild to very grave’’, with an upper limit of 6months’ duration and a subdivision into delirium superimposedon dementia and delirium not superimposed on dementia.The rubric ‘‘other mental disorders due to brain damage anddysfunction and to physical disease’’ includes disorders with‘‘functional’’ characteristics (e.g. hallucinosis, catatonia, schizophrenia-likedisorder, and mood disorders) that arise in thecontext of demonstrable organic illness, such as cerebral disease,systemic disorders and brain dysfunction associated with toxicdisorders (other than due to alcohol or drugs). An important, notyet fully validated, addition to this rubric is the ‘‘mild cognitivedisorder’’ attributable to physical co-morbidity (including HIVdisease), which is defined as transient but nevertheless involvingmemory and learning difficulties.Finally, personality and behavioural disorders due to braindisease, damage and dysfunction include familiar conditions suchas organic personality disorder (the frontal lobe syndrome, but alsoother lesions to circumscribed areas of the brain), postencephaliticsyndrome, postconcussional syndrome and some new entities, e.g.right hemispheric organic affective disorder (altered ability toexpress and comprehend emotion without true depression).In conclusion, two features of ICD-10 should be emphasized.First, as already noted, it does not identify the mental disorders inthe elderly as a separate or special category of psychiatricmorbidity. In addition to the F0 section listing the organic andsymptomatic mental disorders, psychiatric disturbances arising inthe elderly population can be classified, according to theirpresentation and course, in any of the other major sections ofICD-10 (except for F8 and F9, which deal with developmentaldisorders and behavioural and emotional disorders occurring inchildhood and adolescence).Second, although ICD-10 is not explicitly a multi-axialclassification, there are two ways in which multi-axial codingcan be achieved if required. The simplest way is to use extra codesfrom the other chapters of ICD-10 in addition to those inChapter V; any physical disorders present can be recorded bycodes from Chapters I–XIX, and codes from the final twochapters can be used to cover other noteworthy aspects of theclinical picture. These are: Chapter XX, External Causes ofMorbidity and Mortality (the X and Y codes, covering drugscausing adverse effects in therapeutic use, and injuries andpoisoning); and Chapter XXI, Factors Influencing HealthStatus and Contact with Health Services (the Z codes, whichinclude a variety of social, family and life-style factors).Another and more comprehensive option is to use the specialMulti-axial System now available, which was developed bymeans of an international collaborative study organized byWHO Geneva 3 . This provides three descriptive axes: Axis I,Clinical Diagnosis; Axis II, Disablements; and Axis III,Contextual Factors. These Axes are a convenient re-arrangementof the chapters of ICD-10 listed above, with the additionof a brief set of ratings covering physical disabilities.PROSPECTS FOR THE FUTUREIt is likely to be many years before the next edition of theinternational classification is ready for use, but meanwhile thereare plenty of issues worthy of debate. Whatever form theclassification takes, it seems likely that the principle of recordingthe clinical picture by means of Chapter V and the underlyingphysical cause by means of other chapters will remain. Research isnow providing many clues about the exact place and thehistological nature of the lesions in the central nervous systemthat give rise to the clinical syndromes, but the clinical syndromesthemselves will not change, and will always need to be recorded.The new non-invasive techniques for brain imaging, such asMRI, SPECT and PET scans, are demonstrating a variety ofstructural abnormalities in the brains of some (but by no meansall) patients with the familiar clinical syndromes that are alsopresent in substantial proportions of normal subjects. Thesechanges are ‘‘organic’’ in a general sense of being somethingphysical, but not in the way the term is used in the ICD (that is, toindicate a concurrent and diagnosable physical disorder). It willprobably soon be time to abandon ‘‘organic’’ as a term to be usedin a classification, and to develop new terms and concepts that willmake these more subtle differentiations clear.It should be possible to omit the ‘‘nested’’ categories oforganically caused syndromes of depression, anxiety and