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AIDS Care: Psychological and Sociomedical Aspects of AIDS/HIV Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/caic20
Review of neuropsychological studies of HIV infection A. Kocsis
a
a
Principal Clinical Psychologist, Psychology Department , Paterson Wing, St. Mary's Hospital , London, W2 1NY, UK Published online: 25 Sep 2007.
To cite this article: A. Kocsis (1990) Review of neuropsychological studies of HIV infection, AIDS Care: Psychological and Socio-medical Aspects of AIDS/HIV, 2:4, 385-388, DOI: 10.1080/09540129008257759 To link to this article: http://dx.doi.org/10.1080/09540129008257759
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
AIDS CARE, VOL. 2, NO.4,1990
385
Downloaded by [Bibliothèques de l'Université de Montréal] at 18:03 01 December 2014
Review of neuropsychological studies of HIV infection A. KOCSIS Principal Clinical P~chologh,Psychology Department, Patenon Wing,St. Mary’s Hospitac London W2 I N Y , UK
In spite of those who ‘transgressed’ the Those seeking answers from the studies on the Neuropsychology of AIDS could be for- above, many thoughtful and well executed given for feeling somewhat disappointed. studies were presented at this year’s Satellite Considerable resources have clearly been ex- Conference. Since this account can deal only pended on numerous studies. What have with a limited number of these it will aim to these yielded? Often conclusions under- represent areas which are likely to be partimined by the omission or commission of cularly significant given the current ‘state of experimental design sins. Some of the most the art’. salient of these are the following: (1) Omission of control p u p s appropriate to the hypotheses, e.g. controls for practice effects, mood, or most basically, for HIV infection. (2) Presentation of conclusions based on small numbers (under 30 subjects). (3) Omission of mood measures or failure to use the mood measures appropriately to inform analysis of the neuropsychological testing. (4) Failure to exclude patients treated with centrally acting drugs (notably AZT) from natural history study reports. (5) Over-emphasis on ‘trends’ which are not statistically significant. (6) Proliferation of correlations or the presentation of correlations as causes. (7) Limited statistical analysis. For example, the use of M A N O V A may not be appropriate where only some individuals of a group may be cognitively impaired. (8) Failure to control for the effects of learning from repeated testing.
Building theory The studies presented were rather shy about appearing to adopt any theoretical stance. Generally the objective was stated as being the test of a simply hypothesis: that people with HIV show cognitive impairment, relative to people uninfected with the virus. Rationales for the tests used to examine this hypothesis inclined towards the sweeping, e.g. ‘We used tests thought to be sensitive to such impairment’ or ‘We used tests to cover all cognitive processes’. The former appears to read as code for ‘We used tests that we know other people are using’. While in a sense this is laudable, there being advantages to comparabibry between studies, such an approach is somewhat barren and in itself unlikely to allow linkages to be made with the literature on the virological effects of HIV on the CNS. An example would be the guided search for signs of sub-cortical involvement which I have dealt with below.
Downloaded by [Bibliothèques de l'Université de Montréal] at 18:03 01 December 2014
386
SAN FRANCISCO SUMMhRIF.3 A. KOCSlS
triggering factor, perhaps an opportunist infection, activates it? Does it by contrast slowly but progressively affect brain functioning, but initially at a sub-clinical level only? Do the effects vary across individuals, and if so, why and how? The initial assumption underlying many of the earlier studies of asymptomatic seropositives was that there would be an overall group effect. That is, many investigators were proceeding as though they were expecting the majority of their HIV group to be affected, or else none of them. This prompted widespread and understandable use of ANOVAs and MANOVAS. Unfortunately where no group hfferences were found, some investigators declared ‘QED-no difference observed’. Others furrowed on to look at percentages showing impairment by this or that criterion Criteria differed and gave birth to a number of widely spaced percentages. Apart from these methodological problems however, there was also that of the tests used. Brain studies have suggested considerable sub-cortical involvement in AIDS related encephalopathy, an expected neuropsychological consequence of which would be slowed information processing and motor functioning. Surprising therefore that many investigators have made no attempt to assess Impairment amongst asymptomatic the reaction times of their patients in any HN sempositives but the crudest way. This has been a controversial issue in the Notable exceptions to this rule however short life of the neuropsychology of HIV were some of the studies presented this year. infection. There is no doubt that the proba- NPS16,17,22,42,5 all presented data showbility- and the extent-of c o p t i v e impair- ing at least some degree of slowing amongst ment directly associated with HIV infection healthy asymptomatics on a variety of reacincreases with the weakening of the immune tion time tests. It is notable also that no system which marks disease progression. studies reporting the use of reaction time However two main questions have prompted tests reported negative findings. the investigation of mild, or early signs of possible impairment. The first is the emphasis on early intervention and the consequent Causes and clinical correlates of need to identify those who risk developing impairment more serious impairment. The second is the attempt to understand the nature of the While the debate on signs of Central Nerattack mounted by HIV on the Central Ner- vous System involvement in the Asymptovous System. Does it invade early and re- matic HIV seropositives grinds on, the front main entirely non-pathogenic until some runners of what are likely to be a long
There are also other questions to be answered: are there neuropsychological signs of cortical as well as sub-cortical involvement? Do people with HIV show the same practice effects as normals? Are patterns of performance in those with AIDS Dementia similar to patterns found in other dementias? Representing approaches to t h i s latter question was interesting work presented by Hinkin et al. (NPS1) who found that the pattern of performance of those with AIDS Encephalopathy, while differing from those with Alzheimer’s Disease resembled that of the normal elderly. While k s particular study had small numbers and did not consider mood effects, the approach is a worthwhile one in that it can allow us to further hypothesize about the possible brain mechanisms involved and also those spared. It may be interesting to consider for example whether patterns of performance similar to other dementias might suggest neurotransmitter abnormalities in AIDS as in Alzheimer or Parkinson patients (Rossor, 1981; Arendt et al., 1984) or whether neurotransmitter pathways are more likely to be intact.
Downloaded by [Bibliothèques de l'Université de Montréal] at 18:03 01 December 2014
REVIEW OF NEUROPSYCHOLOGICAL STUDIES OF HIV INFEmION
procession of articles on clinical correlates of neuropsychological involvement have come in. It is important to remember that (i) cognitive impairment may have a plethora of causes and (ii) that in the case of HIV, even documented impairment is not necessarily due to direct effects of HIV, or not equally so at all stages of disease. There may be a number of non-specific reasons for underfunctioning, which are nevertheless organic rather than functional. Two studies in this vein are of particular note. The first (NPSS) by Alex Martin and co-workers at the National Institute of Mental Health in the USA found that reaction times in a group of 52 HIV seropositives were significantly slowed compared to negative controls and the seropositives also had elevated levels of Quinolinic Acid in the Cerebrospinal Fluid. Moreover re-testing after 6 months showed further deterioration in reaction times in the seropositive group, accompanied by further increases in Quinolinic Acid levels. Although this article is reviewing presentations at the Satellite conference, a paper presented at San Francisco (FB32) presented by Dr B a r n and the Miami group may be considered relevant here. This concerned slowed reaction times on the Sternberg short-term memory paradigm, on paired associates and on the figure-visual scanning task by asymptomatic seropositives deficient in vitamin B12. Restored levels of this vitamin were associated with improved performance. This was significant only on the Sternberg which showed initial borderline significance (p(0.06). Again we must remember that neither of these studes offer evidence of ‘sufficient cause’. However they both point to the need for examining the role of systemic factors in early or mild impairment.
The effects of mood There is no doubt that disentangling the functional from the organic in analysing the neuropsychological performance of those with HIV or AIDS is a major methodological
387
headache. While reports vary, there is indication from several sources that psychiatric distress increases with disease stage. Robertson et al. (NPS31) rightly point out the need however to use questionnaire measures with caution in this medically ill population. This is not just because of the obvious need to avoid coafoundmg somatic symptoms with signs of depression for example, but also to avoid diagnosing realistic thoughts about the illness as symptoms of depression (Kocsis, 1989). There is some evidence that overall, performance on many neuropsychological tests is correlated with psychiatric symptomatology. (e.g. Kelly et al., NPS43). If indeed this symptomatology increases with disease stage however, as does the incidence of neuropsychological impairment, then the correlations may be an artefact. That there is no group effect of depression as such was indicated by van Gorp et d. (NPS29) who compared neuropsychological performance between those rated as depressed on the Beck Depression Inventory and the Minnesota Multiphasic Personality Inventory. A more sophisticated analysis was conducted by Sarazin et al. (NPS38), a group from Ontario, who analysed the percentage of variance contributed to neuropsychological performance by mood differences. They found that only 6.3% of the variance could be attributed to the emotional factors and that thus performance on at least verbal cognitive skills, rate of information processing and fine motor speed is independent of mood state. A coda to the analysis of the effects of mood is provided by Kocsis et d.(NPS41) who looked at patients’ accuracy in predicting neuropsychological impairment from subjective reports of cognitive changes. Ten measures of subjective change were correlated with neuropsychological performance. However, when the variables were correlated with neuropsychological performance adjusted fos mood using multiple regression, only two measure-decline in activity level and inability to remember events from the past-predicted poor overall performance. Patients’ subjective perception of change is
388
SAN FRANCISCO SUMMARIES: A. KOCSIS
Downloaded by [Bibliothèques de l'Université de Montréal] at 18:03 01 December 2014
much more likely to be a function of anxiety, and for this reason neurologists should be most cautious in classifying someone as being ‘neurologically positive; on the basis of such reported changes. S d a r l y Perdices et ul. (NPS44) found that semistructured psychiatric interview was also likely to overestimate the likelihood of the presence of cogmtive impairment.
Role of neuropsychology in distinguishing opportunist brain infections from direct HIV effects
Finally one area, notable for its sparse information, is nevertheless worthy of mention. Stenquist et al. (NPS46) presented a poster which while dealing with only three patients was provocative. They claimed that neuropsychological testing had successfully detected the presence of Progressive Multifocal Leucoencephalopathy (PML) before any abProgressive encephalopathy in children normalities could be detected with MRI. A number of studies (NPS10-15) vividly Moreover those abnormalities differed from brought home the unequivocal effect of HIV those found in HIV effects on the brain by infection on development in chldren. Devel- indicating focahty and the absence of psyopmental delay, or a progressive loss of de- chomotor slowing. Since PML can only be velopmental milestones clearly occurs even confirmed post-mortem, these findings are in the absence of encephalopathy (Chase et potentially of great interest. Whether or not ul., NPS11). The sahent methodological they will be confirmed with a larger patient sample, the role of neuropsychologists in problems in the area appear to be: trying to differentiate treatable opportunist (1) The investigation of maternal HIV infections from HIV effects is likely to beinfection during gestation, even on those come more substantial. children who are subsequently found to be The detection of opportunist infections uninfected. (2) The evaluation of the efficacy of through cognitive testing would be particucentrally acting drugs on reversing develop- larly valuable in developing countries where laboratory diagnosis of Central Nervous mental delay. The first problem comes from the sad System infection is often not available. Unfact that many of the HIV seropositive fortunately, there was no representation mother-infant pairs currently being studed from developing countries at this conference come from low socio-economic and/or drug- and no mention made of the attempts being using populations. It can therefore be diffi- made to develop culturally appropriate tests cult to attribute underfunctioning relative to for chicians to use in Africa. This is cercontrols as being due to the mother’s infec- tainly an area which needs further emphasis tion. Selection of controls is therefore criti- in the future. cal in &IS as in all areas being studed. Even more so will be the establishment of long- References term prospective studies. The second problem, that of evaluating ARF.NM, T.,BIGL, v., TBNNSIZDT, A. & h N M , A. (1984) Correlation between conical plaque count treatment, poses challenges due to the difand neuronal loss in the nucleus basalis in Alzheferent instruments which are used to meaimer’s disease, Neuroscience Letters, 48, pp. 81-85. sure I.Q. and the attainment of developmen- KOCSIS, A.E. (1989) Changes in cognitions and cognitive changes in HIV and AIDS-factors to contal milestones at different ages. To what sider. Presenred at The World Congress of Cognitive extent are I.Q. scores on different measures Therapy, Oxford. truly comparable? It is possible that a new R o s s o ~ M.N. , (1981) Parkinson’s disease and Alzheirnrange of tests will have to be developed to er’s disease as disorders of the isodendritic core, British Medical Journal, 283, pp. 1588-1590. meet the need for continuous evaluation.
AIDS Care: Psychological and Sociomedical Aspects of AIDS/HIV Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/caic20
Review of neuropsychological studies of HIV infection A. Kocsis
a
a
Principal Clinical Psychologist, Psychology Department , Paterson Wing, St. Mary's Hospital , London, W2 1NY, UK Published online: 25 Sep 2007.
To cite this article: A. Kocsis (1990) Review of neuropsychological studies of HIV infection, AIDS Care: Psychological and Socio-medical Aspects of AIDS/HIV, 2:4, 385-388, DOI: 10.1080/09540129008257759 To link to this article: http://dx.doi.org/10.1080/09540129008257759
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
AIDS CARE, VOL. 2, NO.4,1990
385
Downloaded by [Bibliothèques de l'Université de Montréal] at 18:03 01 December 2014
Review of neuropsychological studies of HIV infection A. KOCSIS Principal Clinical P~chologh,Psychology Department, Patenon Wing,St. Mary’s Hospitac London W2 I N Y , UK
In spite of those who ‘transgressed’ the Those seeking answers from the studies on the Neuropsychology of AIDS could be for- above, many thoughtful and well executed given for feeling somewhat disappointed. studies were presented at this year’s Satellite Considerable resources have clearly been ex- Conference. Since this account can deal only pended on numerous studies. What have with a limited number of these it will aim to these yielded? Often conclusions under- represent areas which are likely to be partimined by the omission or commission of cularly significant given the current ‘state of experimental design sins. Some of the most the art’. salient of these are the following: (1) Omission of control p u p s appropriate to the hypotheses, e.g. controls for practice effects, mood, or most basically, for HIV infection. (2) Presentation of conclusions based on small numbers (under 30 subjects). (3) Omission of mood measures or failure to use the mood measures appropriately to inform analysis of the neuropsychological testing. (4) Failure to exclude patients treated with centrally acting drugs (notably AZT) from natural history study reports. (5) Over-emphasis on ‘trends’ which are not statistically significant. (6) Proliferation of correlations or the presentation of correlations as causes. (7) Limited statistical analysis. For example, the use of M A N O V A may not be appropriate where only some individuals of a group may be cognitively impaired. (8) Failure to control for the effects of learning from repeated testing.
Building theory The studies presented were rather shy about appearing to adopt any theoretical stance. Generally the objective was stated as being the test of a simply hypothesis: that people with HIV show cognitive impairment, relative to people uninfected with the virus. Rationales for the tests used to examine this hypothesis inclined towards the sweeping, e.g. ‘We used tests thought to be sensitive to such impairment’ or ‘We used tests to cover all cognitive processes’. The former appears to read as code for ‘We used tests that we know other people are using’. While in a sense this is laudable, there being advantages to comparabibry between studies, such an approach is somewhat barren and in itself unlikely to allow linkages to be made with the literature on the virological effects of HIV on the CNS. An example would be the guided search for signs of sub-cortical involvement which I have dealt with below.
Downloaded by [Bibliothèques de l'Université de Montréal] at 18:03 01 December 2014
386
SAN FRANCISCO SUMMhRIF.3 A. KOCSlS
triggering factor, perhaps an opportunist infection, activates it? Does it by contrast slowly but progressively affect brain functioning, but initially at a sub-clinical level only? Do the effects vary across individuals, and if so, why and how? The initial assumption underlying many of the earlier studies of asymptomatic seropositives was that there would be an overall group effect. That is, many investigators were proceeding as though they were expecting the majority of their HIV group to be affected, or else none of them. This prompted widespread and understandable use of ANOVAs and MANOVAS. Unfortunately where no group hfferences were found, some investigators declared ‘QED-no difference observed’. Others furrowed on to look at percentages showing impairment by this or that criterion Criteria differed and gave birth to a number of widely spaced percentages. Apart from these methodological problems however, there was also that of the tests used. Brain studies have suggested considerable sub-cortical involvement in AIDS related encephalopathy, an expected neuropsychological consequence of which would be slowed information processing and motor functioning. Surprising therefore that many investigators have made no attempt to assess Impairment amongst asymptomatic the reaction times of their patients in any HN sempositives but the crudest way. This has been a controversial issue in the Notable exceptions to this rule however short life of the neuropsychology of HIV were some of the studies presented this year. infection. There is no doubt that the proba- NPS16,17,22,42,5 all presented data showbility- and the extent-of c o p t i v e impair- ing at least some degree of slowing amongst ment directly associated with HIV infection healthy asymptomatics on a variety of reacincreases with the weakening of the immune tion time tests. It is notable also that no system which marks disease progression. studies reporting the use of reaction time However two main questions have prompted tests reported negative findings. the investigation of mild, or early signs of possible impairment. The first is the emphasis on early intervention and the consequent Causes and clinical correlates of need to identify those who risk developing impairment more serious impairment. The second is the attempt to understand the nature of the While the debate on signs of Central Nerattack mounted by HIV on the Central Ner- vous System involvement in the Asymptovous System. Does it invade early and re- matic HIV seropositives grinds on, the front main entirely non-pathogenic until some runners of what are likely to be a long
There are also other questions to be answered: are there neuropsychological signs of cortical as well as sub-cortical involvement? Do people with HIV show the same practice effects as normals? Are patterns of performance in those with AIDS Dementia similar to patterns found in other dementias? Representing approaches to t h i s latter question was interesting work presented by Hinkin et al. (NPS1) who found that the pattern of performance of those with AIDS Encephalopathy, while differing from those with Alzheimer’s Disease resembled that of the normal elderly. While k s particular study had small numbers and did not consider mood effects, the approach is a worthwhile one in that it can allow us to further hypothesize about the possible brain mechanisms involved and also those spared. It may be interesting to consider for example whether patterns of performance similar to other dementias might suggest neurotransmitter abnormalities in AIDS as in Alzheimer or Parkinson patients (Rossor, 1981; Arendt et al., 1984) or whether neurotransmitter pathways are more likely to be intact.
Downloaded by [Bibliothèques de l'Université de Montréal] at 18:03 01 December 2014
REVIEW OF NEUROPSYCHOLOGICAL STUDIES OF HIV INFEmION
procession of articles on clinical correlates of neuropsychological involvement have come in. It is important to remember that (i) cognitive impairment may have a plethora of causes and (ii) that in the case of HIV, even documented impairment is not necessarily due to direct effects of HIV, or not equally so at all stages of disease. There may be a number of non-specific reasons for underfunctioning, which are nevertheless organic rather than functional. Two studies in this vein are of particular note. The first (NPSS) by Alex Martin and co-workers at the National Institute of Mental Health in the USA found that reaction times in a group of 52 HIV seropositives were significantly slowed compared to negative controls and the seropositives also had elevated levels of Quinolinic Acid in the Cerebrospinal Fluid. Moreover re-testing after 6 months showed further deterioration in reaction times in the seropositive group, accompanied by further increases in Quinolinic Acid levels. Although this article is reviewing presentations at the Satellite conference, a paper presented at San Francisco (FB32) presented by Dr B a r n and the Miami group may be considered relevant here. This concerned slowed reaction times on the Sternberg short-term memory paradigm, on paired associates and on the figure-visual scanning task by asymptomatic seropositives deficient in vitamin B12. Restored levels of this vitamin were associated with improved performance. This was significant only on the Sternberg which showed initial borderline significance (p(0.06). Again we must remember that neither of these studes offer evidence of ‘sufficient cause’. However they both point to the need for examining the role of systemic factors in early or mild impairment.
The effects of mood There is no doubt that disentangling the functional from the organic in analysing the neuropsychological performance of those with HIV or AIDS is a major methodological
387
headache. While reports vary, there is indication from several sources that psychiatric distress increases with disease stage. Robertson et al. (NPS31) rightly point out the need however to use questionnaire measures with caution in this medically ill population. This is not just because of the obvious need to avoid coafoundmg somatic symptoms with signs of depression for example, but also to avoid diagnosing realistic thoughts about the illness as symptoms of depression (Kocsis, 1989). There is some evidence that overall, performance on many neuropsychological tests is correlated with psychiatric symptomatology. (e.g. Kelly et al., NPS43). If indeed this symptomatology increases with disease stage however, as does the incidence of neuropsychological impairment, then the correlations may be an artefact. That there is no group effect of depression as such was indicated by van Gorp et d. (NPS29) who compared neuropsychological performance between those rated as depressed on the Beck Depression Inventory and the Minnesota Multiphasic Personality Inventory. A more sophisticated analysis was conducted by Sarazin et al. (NPS38), a group from Ontario, who analysed the percentage of variance contributed to neuropsychological performance by mood differences. They found that only 6.3% of the variance could be attributed to the emotional factors and that thus performance on at least verbal cognitive skills, rate of information processing and fine motor speed is independent of mood state. A coda to the analysis of the effects of mood is provided by Kocsis et d.(NPS41) who looked at patients’ accuracy in predicting neuropsychological impairment from subjective reports of cognitive changes. Ten measures of subjective change were correlated with neuropsychological performance. However, when the variables were correlated with neuropsychological performance adjusted fos mood using multiple regression, only two measure-decline in activity level and inability to remember events from the past-predicted poor overall performance. Patients’ subjective perception of change is
388
SAN FRANCISCO SUMMARIES: A. KOCSIS
Downloaded by [Bibliothèques de l'Université de Montréal] at 18:03 01 December 2014
much more likely to be a function of anxiety, and for this reason neurologists should be most cautious in classifying someone as being ‘neurologically positive; on the basis of such reported changes. S d a r l y Perdices et ul. (NPS44) found that semistructured psychiatric interview was also likely to overestimate the likelihood of the presence of cogmtive impairment.
Role of neuropsychology in distinguishing opportunist brain infections from direct HIV effects
Finally one area, notable for its sparse information, is nevertheless worthy of mention. Stenquist et al. (NPS46) presented a poster which while dealing with only three patients was provocative. They claimed that neuropsychological testing had successfully detected the presence of Progressive Multifocal Leucoencephalopathy (PML) before any abProgressive encephalopathy in children normalities could be detected with MRI. A number of studies (NPS10-15) vividly Moreover those abnormalities differed from brought home the unequivocal effect of HIV those found in HIV effects on the brain by infection on development in chldren. Devel- indicating focahty and the absence of psyopmental delay, or a progressive loss of de- chomotor slowing. Since PML can only be velopmental milestones clearly occurs even confirmed post-mortem, these findings are in the absence of encephalopathy (Chase et potentially of great interest. Whether or not ul., NPS11). The sahent methodological they will be confirmed with a larger patient sample, the role of neuropsychologists in problems in the area appear to be: trying to differentiate treatable opportunist (1) The investigation of maternal HIV infections from HIV effects is likely to beinfection during gestation, even on those come more substantial. children who are subsequently found to be The detection of opportunist infections uninfected. (2) The evaluation of the efficacy of through cognitive testing would be particucentrally acting drugs on reversing develop- larly valuable in developing countries where laboratory diagnosis of Central Nervous mental delay. The first problem comes from the sad System infection is often not available. Unfact that many of the HIV seropositive fortunately, there was no representation mother-infant pairs currently being studed from developing countries at this conference come from low socio-economic and/or drug- and no mention made of the attempts being using populations. It can therefore be diffi- made to develop culturally appropriate tests cult to attribute underfunctioning relative to for chicians to use in Africa. This is cercontrols as being due to the mother’s infec- tainly an area which needs further emphasis tion. Selection of controls is therefore criti- in the future. cal in &IS as in all areas being studed. Even more so will be the establishment of long- References term prospective studies. The second problem, that of evaluating ARF.NM, T.,BIGL, v., TBNNSIZDT, A. & h N M , A. (1984) Correlation between conical plaque count treatment, poses challenges due to the difand neuronal loss in the nucleus basalis in Alzheferent instruments which are used to meaimer’s disease, Neuroscience Letters, 48, pp. 81-85. sure I.Q. and the attainment of developmen- KOCSIS, A.E. (1989) Changes in cognitions and cognitive changes in HIV and AIDS-factors to contal milestones at different ages. To what sider. Presenred at The World Congress of Cognitive extent are I.Q. scores on different measures Therapy, Oxford. truly comparable? It is possible that a new R o s s o ~ M.N. , (1981) Parkinson’s disease and Alzheirnrange of tests will have to be developed to er’s disease as disorders of the isodendritic core, British Medical Journal, 283, pp. 1588-1590. meet the need for continuous evaluation.
