Mohammed T. Abou-Saleh

290 PRINCIPLES AND PRACTICE OF GERIATRIC PSYCHIATRYTable 53.2StudiesOutcome of investigation of patients presenting with clinical symptoms of dementiaAlmeida et al. 13 Freter et al. 15 Hogh et al. 18Brodaty 12Ames et al. 14Chui & Zhang 16Walstra et al. 17Memory clinic specialty Geriatric psychiatry Geriatrics NeurologyTotal patients studied (n) 558 405 719Clinical dementia confirmed [n (%)] 368 (100) 270 (100) 451 (100)Mean age (range) (years) 70 (44–90) 76 (49–92) 66 (19–97)Potentially reversible dementiasSecondary dementias [n (%)]: 7 (1.9) 25 (9.3) 61 (13.5)Normal pressure hydrocephalus – 6 20Brain tumour – 2 1Vitamin B 12 deficiency – 11 27Folate deficiency 1 –Hypothyroidism 1 3 8Hyperthyroidism – 1Positive syphilis serology 1 3 4Alcoholic dementia 4 –Drug intoxication and metabolic disorders [n (%)]: 0 13 (4.8) 0Alcohol abuse – 2 –Drug toxicity – 11 –Psychiatric disorders [n (%)]: 0 23 (8.5) 7 (1.6)Depression – 23 7Follow-up period (months) 46 44 6 {‘True’ reversible dementia [n (%)] 0 5 (1.9) 2 (0.4) {{ Not stated in Hogh et al. 18 Table 53.3 Physical investigations for the assessment of an elderly patientRESPONSE TO TREATMENTThe degree to which reversible dementias are, in fact, reversiblehas long been the subject of debate. Rabins 22 reported someimprovement in two-thirds of patients and complete recovery in40%. This looks optimistic, judging by the results presented inTable 53.2 of between 0% and 2% reversibility.A number of conditions deserve special mention. Depressive‘‘pseudodementia’’ has traditionally been viewed as a treatablecondition, with a distinct clinical history and symptoms thatdistinguish it from ‘‘true’’ dementia 23 . In an attempt to improvethe clinical discrimination between depressive pseudodementiaand progressive dementia, Yousef et al. 24 derived a rating scalefrom a large number of possible discriminating features. Validatingthe diagnosis 12–14 months later, the scale allowed correctclassification of 98% of true dementia cases and 95% ofdepression cases. Longer-term follow-up studies tend to supportthe view that severe cognitive impairment in depression is aharbinger of true dementia in 25–50% of patients 24–26 . Alexopouloset al. 26 found that, after 2–3 years, elderly depressed patientswho also fulfilled DSM–III criteria for dementia were nearly fivetimes more likely to develop dementia than those withoutcognitive impairment at presentation. The issue is furthercomplicated by the high prevalence of depressive symptoms indementia 27 .Several authors have questioned the usefulness of routinesyphilis serology 28–30 , while others have defended routine testingon the grounds that even one missed case would be catastrophicfor the individual patient 31 . However, the erroneous diagnosis ofactive syphilis perhaps carries with it equally dire consequences,particularly when false positives may occur as a result of yaws andother non-venereal treponemal infection 32 . Hilton 33 has suggestedthat treatment should not be based solely on positive serology andthat testing for syphilis should be dealt with in the same way asHIV testing and require informed consent where possible.Normal pressure hydrocephalus is the most common neurologicalcause of reversible dementia 16–18 . However, the results ofshunting operations indicate high rates of post-operativecomplications, including death, as well as a lack of evidenceof effectiveness 34–35 . The best results are obtained in patientsunder the age of 60 years who present with dementia of lessthan 6 months’ duration 34 .Clearly, the lack of reversibility revealed by the studies listed inTable 53.2 suggests that most of the associated disorders are reallyconcomitant with true dementia, rather than of aetiologicalsignificance. They may also be secondary to the dementia, e.g.anaemia as a result of malnutrition. Hogh et al. 18 reported that45% of those with dementia were found to have concomitantdisorders. Although treatment of depressive symptoms indementia has been shown to improve some aspects of cognitionand everyday function 36,37 , there is little evidence to show that thecorrection of other disorders, such as hypothyroidism or vitaminB 12 deficiency, has similar benefits 17,38,39 .presenting with cognitive impairmentRoutine investigations (all cases)Full blood count a,b,cErythrocyte sedimentation rate bRenal function a,b,cLiver function a,b,cThyroid function a,b,cCalcium a,b,ccVitamin B 1a,b,cVitamin B 12Folate b,cGlucose a,b,cSyphilis serology a,cSpecial investigations(atypical cases or clinically indicated)Brain CT or MRI a,b,cEEG a,cChest X-ray a,b,cElectrocardiogram b,cLumbar puncture a,cUrine for culture a,bHIV testing aToxicity screen aAuto-antibody screen bRecommendations for investigations: a American Academy of Neurology 40 ; b RoyalCollege of Psychiatrists 42 ; c Dutch Consensus statement 44 .