Mohammed T. Abou-Saleh

188 PRINCIPLES AND PRACTICE OF GERIATRIC PSYCHIATRYThe temporal relationship between stroke and onset ofdementia is often thought to strengthen the possibility that thetwo disorders are aetiologically related. The NINDS–AIRENcriteria suggest an arbitrary limit of 3 months for onset ofdementia after stroke. However, a stroke which occurred yearsbefore may still indicate the presence of CVD.VAD may be underdiagnosed, as sometimes the onset isinsidious, the course gradual, the infarctions clinically silent andthe infarcts not detectable by CT of the brain 17,18 . VAD may beoverdiagnosed, as the presence of stroke, WMLs or other CVDdoes not necessarily mean that they are the cause of thedementia 17 . Often AD becomes a diagnosis by exclusion, andthe diagnosis of VAD will be assigned if the patient has a historyof CVD. This leads to a situation where the dementias will notinfrequently be divided into one group with stroke and onewithout, giving negative associations between risk factors forstroke and AD, and positive associations with VAD 17 .Even the histopathological diagnoses of AD and VaD areuncertain. Extensive histopathological signs of AD 19,20 andVAD 19,21 have been found in persons who show no clinical signsof dementia during life. A considerable proportion of subjectsfulfilling the diagnosis of probable NINCDS–ADRDA criteria forAD or probable NINDS–AIREN for VAD have mixed pathologies22,23 . CVD may increase the possibility that individuals withAD lesions in their brains will express a dementia syndrome 24 , butsome workers have suggested that there may be a causal linkbetween AD and VAD 25 .Frontotemporal DementiaFrontotemporal dementia is a neurodegenerative disease characterizedby neuronal loss in the frontal and temporal lobes.Criteria for frontotemporal dementia was proposed by the Lundand Manchester Groups in 1994 26 , and revised in 1998 27 . Thelatter describes five core diagnostic features that must be present:(a) insidious onset and gradual progression; (b) early decline insocial interpersonal conduct; (c) early impairment in regulation ofpersonal conduct (e.g. social disinhibition); (d) early emotionalblunting (such as inertia and loss of volition); and (e) early loss ofinsight. It also includes supportive diagnostic features, which arenot present in all patients: (a) behavioural disorder; (b) speech andlanguage alterations (economical output, reduced number ofwords, aspontaneity, press of speech, stereotypy, echolalia,mutism, perseveration); (c) physical signs (primitive reflexes,incontinence, akinesia, rigidity, tremor, low or labile bloodpressure); (d) investigations showing impairment in frontal lobetests in the absence of severe amnesia, aphasia or perceptualdisorder, normal EEG, and frontal or anterior temporalabnormality on CBF. Other common symptoms are stereotypedbehaviour and motor perseverations. Cognitive deficits occurmainly in attention, abstraction, planning and problem solving,while memory is relatively well-preserved in the early phase 27 .InDSM-IV and ICD-10, this type of dementia is classified under theheading Dementia due to Pick’s disease, while Pick’s disease is asubtype of frontotemporal dementia in the criteria from Neary etal 27 . According to the ICD-10, the general criteria for dementiashould be met, onset should be slow with steady deterioration,memory and parietal lobe functions should be relatively preservedin the early stages, and at least two symptoms should be eitheremotional blunting, coarsening of social behaviour, disinhibition,apathy or restlessness, and aphasia. The problem with theemphasis on memory impairment in the general criteria fordementia in this disorder is evident.Two other clinical syndromes of frontotemporal degenerationare progressive nonfluent aphasia and semantic dementia, whichare disorders of language. Patients with Alzheimer’s disease,vascular dementia, and some other brain disorders may alsoexhibit symptoms of the frontal lobe type during the course oftheir disorders.Lewy Body DementiaLewy body disease is a neurodegenerative dementia characterizedby Lewy body formation in the brain stem and cerebral cortex. Ithas been reported that as much as 20% of demented patientscoming to autopsy exhibit these changes. Criteria for Lewy bodydementia are lacking in DSM-IV and ICD-10, but were proposedby McKeith et al 28 in 1992. These include: (a) fluctuating cognitiveimpairment affecting both memory and higher cortical functions;(b) at least one of (i) visual and/or auditory hallucinations, (ii)mild spontaneous extrapyramidal features (mainly rigidity andhypokinesia) or a neuroleptic sensitivity syndrome (i.e. exaggeratedadverse response to standard doses of neurolepticmedications), or (iii) repeated unexplained falls and/or transientclouding or loss of consciousness; (c) despite the fluctuatingpattern the clinical features persist over a long period of time; (d)exclusion of any underlying physical illness adequate to explainthe fluctuating cognitive state, and of past history of stroke orischaemic brain damage on brain imaging. The clinical presentationoften also includes paranoid ideations and depression.Subcortical DementiaA special subtype of dementia is subcortical dementia. This typeof dementia is seen in subcortical disorders, such as Parkinson’sdisease with dementia, Huntington’s disease, supranuclear palsy,Lewy body disease and subcortical ischaemic WMLs. Thedominating symptoms are psychomotor retardation, emotionalbluntness, akinesia and slight memory disturbance, which may behelped by cues.Secondary DementiasSecondary dementias are caused by conditions with a knownaetiology where dementia is generally not a core symptom, butmay occur in some patients. Traditionally, vascular dementia isnot classified among the secondary dementias, while subduralhaematomas, normal pressure hydrocephalus, Creutzfeldt–Jakobdisease, brain tumours, metabolic disorders and deficiency statesare treated as secondary dementias.REFERENCES1. American Psychiatric Association. Diagnostic and Statistical Manual ofMental Disorders, 3rd edn, revised. Washington, DC: AmericanPsychiatric Association, 1987.2. American Psychiatric Association. Diagnostic and Statistical Manual ofMental Disorders, 4th edn. Washington, DC: American PsychiatricAssociation, 1994.3. World Health Organization. The ICD-10 Classification of Mental andBehavioural Disorders. Diagnostic Criteria for Research. Geneva:World Health Organization, 1993.4. Henderson AS, Huppert FA. The problem of mild dementia. PsycholMed 1984; 14: 5–11.5. Mowry B, Burvill P. A study of mild dementia in the communityusing a wide range of diagnostic criteria. Br J Psychiat, 1988; 153:328–34.6. Aevarsson O, Skoog I. Dementia disorders in a birth cohort followedfrom age 85 to 88. The influence of mortality, non-response anddiagnostic change on prevalence. Int Psychogeriat 1997; 9: 11–23.