COMMENTARY
HIV testing in dementia: test some, perhaps more, but not all Jonathan M Schott Correspondence to Dr Jonathan M Schott, Dementia Research Centre, Department of Neurodegenerative Disease, Institute of Neurology, UCL, Queen Square, London WC1N 3BG, UK;[email protected]
To cite: Schott JM. Pract Neurol 2013;13:357–358.
Nightingale et al argue that all patients presenting to neurologists with cognitive impairment should undergo HIV testing.1 This view, prompted by a highly unusual case of a patient with HIV-related cognitive impairment, is based on the following reasoning: HIV is potentially treatable and testing is quick and relatively inexpensive; dementia is listed as an indication for testing by the British HIV Association, and suspected encephalitis is an indication for HIV testing in the Association of British Neurologists and British Infectious Association National Encephalitis guidelines; increasing age does not exclude HIV; and HIV is much more common than other ‘routinely’ tested potential causes of dementia, such as syphilis. The authors suggest that clinicians’ reluctance to test for HIV partly relates to misconceptions about the need for extended pre-test counselling. Undoubtedly HIV can be associated with dementia, is easily tested and potentially treatable. However, before accepting that blanket HIV testing is warranted in all patients with dementia, it is important to consider how most patients with dementia present and the context in which they are seen. The vast majority of individuals presenting with cognitive impairment are elderly, with many—if not the majority—being older than the oldest case the authors have ever diagnosed with HIV (aged 76). Most patients present with slowly progressive neurodegenerative disorders, the commonest of which is Alzheimer’s disease. Where a clinical diagnosis of Alzheimer’s disease is subsequently shown to be incorrect at postmortem, other neurodegenerative pathologies2 are overwhelmingly likely to be the underlying cause. While it is possible that some elderly people with an insidious onset of progressive cognitive impairment suggestive of neurodegenerative pathology may have undiagnosed
Schott JM. Pract Neurol 2013;13:357–358. doi:10.1136/practneurol-2013-000746
HIV infection, in the absence of evidence to the contrary the numbers are likely to be vanishingly small, at least in a typical Western clinic population. Presuming such cases do exist, such is the prevalence of Alzheimer’s in the elderly that it may well be that any cognitive impairment is due to amyloid plaques and neurofibrillary tangles rather than primary HIV infection, albeit with the possibility that the two might be mechanistically linked. I suspect that members of the British HIV Association are unlikely to see many 80-year-olds presenting with amnestic syndromes developing over several years, perhaps explaining the differences between their guidelines regarding HIV testing and the more muted suggestion from the European Federation of Neurosciences that “tests for syphilis, Borrelia and HIV should be considered in individual cases at high risk or where there are suggestive clinical features”.3 In contrast to the assertion that syphilis serology is done routinely, the American Academy of Neurology guidelines for the evaluation of dementia clearly state that “syphilis screening should not be included in the routine evaluation of the demented patient … unless the patient has a specific risk factor”.4 The situation may well be different in patients with young (or younger) onset dementia, where the a priori chance of having a neurodegenerative dementia is lower, and the differential diagnosis of cognitive decline is more extensive.5 This may be the implication of the authors’ statement that “all patients with cognitive impairment presenting to neurologists should undergo HIV testing”. While younger patients or those with more unusual forms of dementia are typically those referred to neurologists in the UK, this is not the case in other countries where a neurologist will be the first port of call for all patients with cognitive impairment, regardless of age. Even in
357
COMMENTARY the context of young onset dementia, I would question the appropriateness of immediate or routine HIV testing in, say, a 60-year-old presenting with typical features of a slowly evolving neurodegenerative disease, unless the clinical evaluation—the cornerstone of the evaluation of a patient with cognitive impairment—revealed any unusual or atypical features; or subsequent investigations raise any doubts about the diagnosis. An important point is that suspected encephalitis and cognitive decline are not synonymous, have a different range of potential causes and should not be used interchangeably. These issues aside, HIV is clearly a much more treatable cause of cognitive decline than many other causes currently tested more routinely. While it is important not to be overly influenced by isolated rare cases such as the one described, clinicians should have an (increasingly) low threshold for considering HIV testing in unusual scenarios, including rapidly progressive dementia; in high-risk groups or in endemic areas; in younger patients or where there is reasonable doubt about the underlying cause. Doctors should not feel intimidated about requesting consent for HIV testing—which after all is more likely to directly influence an individual patient’s care than requesting a genetic test for an untreatable neurodegenerative condition—when appropriate. Conversely, clinicians must also balance the sensitivities of requesting HIV testing —which rightly or wrongly still may carry stigma perhaps particularly in some elderly patients—with the chance of finding a positive result. I agree that perhaps the time has come to establish the prevalence of HIV in a range of different dementia settings and would suggest that this is also an opportunity to
358
establish the views of patients and their carers about approaches to testing. While, at least in my view, there is not currently sufficient evidence to suggest routine HIV testing for all patients with cognitive impairment, striving for an accurate diagnosis of the cause of an individual’s dementia is vital. By reminding us that HIV may cause isolated cognitive decline potentially even in the (rather more) elderly, the authors have done our patients a service. Acknowledgement The author is an HEFCE/NHS Clinical Senior Lecturer and is grateful for the support of the Queen Square Dementia BRU, The Leonard Wolfson Experimental Neurology Centre, and Alzheimer’s Research UK. Competing interests None. Provenance and peer review Commissioned; internally peer reviewed.
REFERENCES
1 Nightingale S, Michael BD, Defres S, et al. Test them all; an easily diagnosed and readily treatable cause of dementia with life threatening consequences if missed. Pract Neurol 2013. 2 Beach TG, Monsell SE, Phillips LE, et al. Accuracy of the clinical diagnosis of Alzheimer disease at national institute on aging Alzheimer disease centers, 2005–2010. J Neuropathol Exp Neurol 2012;71:266–73. 3 Hort J, O’Brien JT, Gainotti G, et al. EFNS guidelines for the diagnosis and management of Alzheimer’s disease. Eur J Neurol 2010;17:1236–48. 4 Knopman DS, DeKosky ST, Cummings JL. Practice parameter: diagnosis of dementia (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2001;56:1143–53. 5 Rossor MN, Fox NC, Mummery CJ, et al. The diagnosis of young-onset dementia. Lancet Neurol 2010;9:793–806.
Schott JM. Pract Neurol 2013;13:357–358. doi:10.1136/practneurol-2013-000746
HIV testing in dementia: test some, perhaps more, but not all Jonathan M Schott Correspondence to Dr Jonathan M Schott, Dementia Research Centre, Department of Neurodegenerative Disease, Institute of Neurology, UCL, Queen Square, London WC1N 3BG, UK;[email protected]
To cite: Schott JM. Pract Neurol 2013;13:357–358.
Nightingale et al argue that all patients presenting to neurologists with cognitive impairment should undergo HIV testing.1 This view, prompted by a highly unusual case of a patient with HIV-related cognitive impairment, is based on the following reasoning: HIV is potentially treatable and testing is quick and relatively inexpensive; dementia is listed as an indication for testing by the British HIV Association, and suspected encephalitis is an indication for HIV testing in the Association of British Neurologists and British Infectious Association National Encephalitis guidelines; increasing age does not exclude HIV; and HIV is much more common than other ‘routinely’ tested potential causes of dementia, such as syphilis. The authors suggest that clinicians’ reluctance to test for HIV partly relates to misconceptions about the need for extended pre-test counselling. Undoubtedly HIV can be associated with dementia, is easily tested and potentially treatable. However, before accepting that blanket HIV testing is warranted in all patients with dementia, it is important to consider how most patients with dementia present and the context in which they are seen. The vast majority of individuals presenting with cognitive impairment are elderly, with many—if not the majority—being older than the oldest case the authors have ever diagnosed with HIV (aged 76). Most patients present with slowly progressive neurodegenerative disorders, the commonest of which is Alzheimer’s disease. Where a clinical diagnosis of Alzheimer’s disease is subsequently shown to be incorrect at postmortem, other neurodegenerative pathologies2 are overwhelmingly likely to be the underlying cause. While it is possible that some elderly people with an insidious onset of progressive cognitive impairment suggestive of neurodegenerative pathology may have undiagnosed
Schott JM. Pract Neurol 2013;13:357–358. doi:10.1136/practneurol-2013-000746
HIV infection, in the absence of evidence to the contrary the numbers are likely to be vanishingly small, at least in a typical Western clinic population. Presuming such cases do exist, such is the prevalence of Alzheimer’s in the elderly that it may well be that any cognitive impairment is due to amyloid plaques and neurofibrillary tangles rather than primary HIV infection, albeit with the possibility that the two might be mechanistically linked. I suspect that members of the British HIV Association are unlikely to see many 80-year-olds presenting with amnestic syndromes developing over several years, perhaps explaining the differences between their guidelines regarding HIV testing and the more muted suggestion from the European Federation of Neurosciences that “tests for syphilis, Borrelia and HIV should be considered in individual cases at high risk or where there are suggestive clinical features”.3 In contrast to the assertion that syphilis serology is done routinely, the American Academy of Neurology guidelines for the evaluation of dementia clearly state that “syphilis screening should not be included in the routine evaluation of the demented patient … unless the patient has a specific risk factor”.4 The situation may well be different in patients with young (or younger) onset dementia, where the a priori chance of having a neurodegenerative dementia is lower, and the differential diagnosis of cognitive decline is more extensive.5 This may be the implication of the authors’ statement that “all patients with cognitive impairment presenting to neurologists should undergo HIV testing”. While younger patients or those with more unusual forms of dementia are typically those referred to neurologists in the UK, this is not the case in other countries where a neurologist will be the first port of call for all patients with cognitive impairment, regardless of age. Even in
357
COMMENTARY the context of young onset dementia, I would question the appropriateness of immediate or routine HIV testing in, say, a 60-year-old presenting with typical features of a slowly evolving neurodegenerative disease, unless the clinical evaluation—the cornerstone of the evaluation of a patient with cognitive impairment—revealed any unusual or atypical features; or subsequent investigations raise any doubts about the diagnosis. An important point is that suspected encephalitis and cognitive decline are not synonymous, have a different range of potential causes and should not be used interchangeably. These issues aside, HIV is clearly a much more treatable cause of cognitive decline than many other causes currently tested more routinely. While it is important not to be overly influenced by isolated rare cases such as the one described, clinicians should have an (increasingly) low threshold for considering HIV testing in unusual scenarios, including rapidly progressive dementia; in high-risk groups or in endemic areas; in younger patients or where there is reasonable doubt about the underlying cause. Doctors should not feel intimidated about requesting consent for HIV testing—which after all is more likely to directly influence an individual patient’s care than requesting a genetic test for an untreatable neurodegenerative condition—when appropriate. Conversely, clinicians must also balance the sensitivities of requesting HIV testing —which rightly or wrongly still may carry stigma perhaps particularly in some elderly patients—with the chance of finding a positive result. I agree that perhaps the time has come to establish the prevalence of HIV in a range of different dementia settings and would suggest that this is also an opportunity to
358
establish the views of patients and their carers about approaches to testing. While, at least in my view, there is not currently sufficient evidence to suggest routine HIV testing for all patients with cognitive impairment, striving for an accurate diagnosis of the cause of an individual’s dementia is vital. By reminding us that HIV may cause isolated cognitive decline potentially even in the (rather more) elderly, the authors have done our patients a service. Acknowledgement The author is an HEFCE/NHS Clinical Senior Lecturer and is grateful for the support of the Queen Square Dementia BRU, The Leonard Wolfson Experimental Neurology Centre, and Alzheimer’s Research UK. Competing interests None. Provenance and peer review Commissioned; internally peer reviewed.
REFERENCES
1 Nightingale S, Michael BD, Defres S, et al. Test them all; an easily diagnosed and readily treatable cause of dementia with life threatening consequences if missed. Pract Neurol 2013. 2 Beach TG, Monsell SE, Phillips LE, et al. Accuracy of the clinical diagnosis of Alzheimer disease at national institute on aging Alzheimer disease centers, 2005–2010. J Neuropathol Exp Neurol 2012;71:266–73. 3 Hort J, O’Brien JT, Gainotti G, et al. EFNS guidelines for the diagnosis and management of Alzheimer’s disease. Eur J Neurol 2010;17:1236–48. 4 Knopman DS, DeKosky ST, Cummings JL. Practice parameter: diagnosis of dementia (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2001;56:1143–53. 5 Rossor MN, Fox NC, Mummery CJ, et al. The diagnosis of young-onset dementia. Lancet Neurol 2010;9:793–806.
Schott JM. Pract Neurol 2013;13:357–358. doi:10.1136/practneurol-2013-000746
