be accompanied by a 'silent epidemic' of dementia that will impact upon all aspects of health care. ... 'Silence is golden' - but can we afford to listen? Andrew ...
Srikanth et al: Reversible dementias
reversible dementia could have added more diagnostic information. Lastly it is our view that a higher proportion of patients could have been identified if we had included serum vitamin B12 assay, VDRL and thyroid antimicrosomal antibody estimation in the mandatory laboratory assessment for all patients. We are encouraged along this path by the finding of very high thyroid anti-microsomal antibodies in a recent patient with the clinical picture of posterior cortical atrophy. We still await results of treatment with corticosteroids though.
Conclusions Not withstanding the above shortcomings, this investigation has indeed thrown up valuable results that will surely help fine tune the clinical diagnostic approach to dementia. If we have a heightened awareness of neuroinfections and vitamin B12 deficiency as common causes of dementia that might be substantially reversible and focus on the particular clinical profile to help direct subsequent investigations, the lessons from this study would have been truly learnt.
7. 8. 9. 10. 11.
12.
13. 14. 15.
16.
17.
18.
Acknowledgement The authors would like to place on record their gratitude for Dr.E.Ratnavalli who helped at all stages of this study.
19. 20. 21.
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Evans DA, Funkenstein HH, Albert MS, Scherr PA, Cook NR, Chown MJ,et al. Prevalence of Alzheimer’s disease in a community population of older persons.Higher than previously reported.JAMA. 1989;262:2551-6. Shaji S, Bose S, Verghese A. Prevalence of dementia in an urban population in Kerala, India. Br J Psychiatry. 2005;186:136-40. Vas CJ, Pinto C, Panikker D, Noronha S, Deshpande N, Kulkarni L, et al. Prevalence of dementia in an urban Indian population. Int Psychogeriatr. 2001;13:439-50. Chandra V, Ganguli M, Pandav R, Johnston J, Belle S. Prevalence of Alzheimer’s disease and other dementias in rural India. The Indo-US study. Neurology. 1998;51:1000-1008. Rajkumar S, Kumar S, Thara R. Prevalence of dementia in a rural setting: A report from India. Int J Geriatr Psychiatry. 1997;12:702-7. Shaji S, Promodu K, Abraham T, Roy KJ, Verghese A. An epidemiological
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study of dementia in a rural community in Kerala, India. Br J Psychiatry. 1996;168:745-9. Clarfield AM. The reversible dementias: do they reverse? Ann Intern Med. 1988;109:476-86. Weytingh MD, Bossuyt PM, van Crevel H. Reversible dementia: more than 10% or less than 1%? A quantitative review. J Neurol. 1995;242:466-71. Clarfield AM. The decreasing prevalence of reversible dementias: an updated meta-analysis. Arch Intern Med. 2003;163:2219-29. Piccini C, Bracco L, Amaducci L.Treatable and reversible dementias: an update. J Neurol Sci. 1998;153:172-81. Folstein MF, Folstein SE, McHugh PR. “Mini-mental state”. A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12:189-98. Cummings JL, Mega M, Gray K, Rosenberg-Thompson S, Carusi DA, Gornbein J. The Neuropsychiatric Inventory: comprehensive assessment of psychopathology in dementia. Neurology. 1994;44:2308-14. Morris JC. The Clinical Dementia Rating (CDR): current version & scoring rules. Neurology. 1993;43:2412-4. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, ed 4.Washington, DC: American Psychiatric Association, 1994. McKhann G, Drachman D, Folstein M, Katzman R, Price D, Stadlan EM. Clinical diagnosis of Alzheimer’s disease: report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task Force on Alzheimer’s Disease. Neurology 1984; 34:939-44. Roman GC, Tatemichi TK, Erkinjuntti T, Cummings JL, Masdeu JC, Garcia JH, et al. Vascular dementia: diagnostic criteria for research studies. Report of the NINDS- AIREN International Workshop. Neurology. 1993;43:250-60. Neary D, Snowden JS, Gustafson L, Passant U, Stuss D, Black S, et al. Frontotemporal lobar degeneration: a consensus on clinical diagnostic criteria. Neurology. 1998;51:1546-54. World Health Organization. International statistical classification of diseases and related health problems, tenth revision. Geneva: World Health Organization, 1992. Larson EB, Reifler BV, Featherstone HJ, English DR. Dementia in elderly outpatients: a prospective study. Ann Intern Med. 1984; 100:417-23. Erkinjuntti T, Sulkava R, Kovanen J, Palo J. Suspected dementia: evaluation of 323 consecutive referrals. Acta Neurol Scand. 1987; 76:359-64. Hejl A, Hogh P, Waldemar G. Potentially reversible conditions in 1000 consecutive memory clinic patients. J Neurol Neurosurg Psychiatry. 2002;73:390-4. Walstra GJ, Teunisse S, van Gool WA, van Crevel H. Reversible dementia in elderly patients referred to a memory clinic. J Neurol. 1997;244:17-22. Takada LT, Caramelli P, Radanovic M, Anghinah R, Hartmann AP, Guariglia CC, et al. Prevalence of potentially reversible dementias in a dementia outpatient clinic of a tertiary university-affiliated hospital in Brazil. Arq Neuropsiquiatr. 2003;61:925-9. Jha S, Patel R. Some observations on the spectrum of dementia. Neurol India. 2004; 52:213-4. Freter S, Bergman H, Gold S, Chertkow H, Clarfield AM. Prevalence of potentially reversible dementias and actual reversibility in a memory clinic cohort. CMAJ. 1998; 159:657-62. DeKosky ST, Kaufer DI and Lopez OL. The Dementias. In: Bradley WG et al, eds. Neurology in Clinical Practice. Philadelphia: Butterworth Heinemann, 2004:1901-52.
Accepted on 23-07-2005
Invited Comments
It has long been recognised that our ageing population will be accompanied by a ‘silent epidemic’ of dementia that will impact upon all aspects of health care. In a prescient discussion of its implications, Beck et al observed that many ameliorable diseases in the elderly are associated with intellectual impairment that may be difficult to distinguish from irreversible brain disease [1]. In this issue of Neurology India, Srikanth 294 294 CMYK
et al address this important topic in a prospective study of 129 referrals to a hospital neurological unit for evaluation of cognitive disorder[2]. They discovered reversible dementias in 18% of the study sample; 11 patients had neuroinfections, 8 had normal pressure hydrocephalus and 5 were vitamin B12 deficient. The majority of these cases were clinically unsuspected but showed substantial improvement with treatment. Neurology India | September 2005 | Vol 53 | Issue 3
Srikanth et al: Reversible dementias
Dementia prevalence in elderly individuals in Southern India is estimated to be 33.6 per 1000[3]. It is striking that nearly one fifth might have a reversible dementia. In fact, the true prevalence of reversible dementia may be even higher. Srikanth et al excluded patients with alcoholic dementia, depressive pseudodementia, intracranial tumours and subdural haematomas; these patients were referred to other departments for follow up. Furthermore serum B12 assays were only performed ‘as deemed necessary’, but the haematological and neurological features of B12 deficiency are often unrelated in such patients.[4] The advent of sensitive but expensive tests such as homocysteine and holotranscobalamin assays now makes it possible to detect such subtle deficiencies.[5] However, there is a difficult but important ‘cost/benefit’ issue to be addressed. Should every patient presenting with dementia be extensively investigated for potentially reversible causes with an inherent increase in diagnostic costs? Hence it is helpful that Srikanth et al describe a distinct clinical profile to alert physicians to the possible presence of reversibility. They found that a subcortical pattern of dementia in younger patients with a short duration of symptoms was suggestive of
an underlying reversible cause. Clearly more work is required to develop cost-effective clinical algorithms for the investigation of patients with cognitive disorders. As the authors note, this has special relevance for countries like India where reversible etiologies are likely to be common but diagnostic resources scarce. ‘Silence is golden’ but can we afford to listen?
Andrew McCaddon Department of General Practice, Wales College of Medicine, Wrexham, UK
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Bec, JC, Benson DF, Scheibel AB, Spar JE, Rubenstein LZ. Dementia in the Elderly. The Silent Epidemic. Ann Intern Med 1982;97:231-41. Srikanth S, Nagaraja AV. Prospective Study of Reversible Dementias - Frequency, Causes, Clinical Profile and Results of Treatment. Neurol India 2005;53:291-6 Shaji S, Bose S, Verghese A. Prevalence of Dementia in an Urban Population in Kerala, India. Br. J Psychiatry 2005;186:136-40. McCaddon A, Tandy S, Hudson P, Gray R, Davies G, Hill D, Duguid J. Absence of Macrocytic Anaemia in Alzheimer’s Disease. Clin Lab Haematol. 2004;26:25963. Hvas AM, Nexo E. Holotranscobalamin-a First Choice Assay for Diagnosing Early Vitamin B Deficiency? J Intern Med 2005;257:289-98.
Invited Comments
The majority of dementing illnesses are degenerative or vascular. A proportion of them (2–30%), however, are fully or partially reversible. They have two underlying mechanisms, which may coexist.[1] The dementia is caused by a potentially treatable condition.[2] There is a potentially treatable co-morbid condition that amplifies the underlying dementia (or rarely mimics it). The latter commonly includes drugs (CNS stimulants/depressants), depression and septic/metabolic (or rarely endocrinal) encephalopathy. The former includes cerebral infections, nutritional deficiencies, toxins, brain irradiation, structural lesions (NPH, subdural hematomas, etc.), primary/ secondary CNS vasculitis, metabolic/endocrinal disturbances (e.g., thyroid dysfunction), and primary/secondary brain tumors. The co-morbid conditions require a high index of clinical suspicion and very few investigations and treating them is often rewarding. In contrast, the causative conditions require an extensive diagnostic work-up. Even though beneficial in some individual cases, it is debatable if it is cost-effective in the diagnostic work-up of a syndrome, which in the majority of cases requires very limited investigations. Only systematic longitudinal follow-up studies of such patients can throw more light on the necessity, yield, and indications of various inves-
Neurology India | September 2005 | Vol 53 | Issue 3
tigations in such reversible dementias. Systematic meta analysis of studies, mainly on the Western population, have shown that potentially reversible causes account for perhaps less than a 10th of the dementing syndromes, less than a 10th of which are actually reversed with appropriate treatment.[1] Depression accounts for the majority of reversible causes while investigations for other conditions are cost-ineffective.[2] Well-conducted studies from the developing countries, including India, are limited. A recent retrospective hospital-based study on 275 dementia patients (mean age ~ 75 years) in Brazil reported 8% prevalence of potentially reversible dementia of which only 9% reverted in full and 45% partially.[3] Two recent hospital-based reports from India provide unusually high rates of potentially reversible dementia, ~32% (n = 76, age < 65 years)[4] and ~38% (traumas and tumors excluded, n = 124, age > 60 years).[5] Follow-up duration was insufficient for drawing meaningful conclusions. This issue carries a report of a hospital-based prospective 1-year follow-up study on reversible dementias.[6] The methodology is sound and the analysis and reporting good. The authors find a prevalence of 18% in 129 consecutive patients (40 years of age) referred for cognitive complaints, which
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