Neuropsychiatric Assessment of Vascular Dementia

Transcription

1 Forayssa M. Talaat et al. Neuropsychiatric Assessment of Vascular Dementia Forayssa M. Talaat 1, Maha A. Zaki 1, Abd El-Rahman A. Asal 2, Mohamed El-Sayed 1, Shereen Fathi 1, Rasha Hassan 1, Hala abd El-Mageed 1, Hatem El-Sayed 1 Departments of Neurology 1, Psychiatry 2, Cairo University ABSTRACT Background: Vascular dementia (VD) is the second most common cause of dementia after Alzheimer s disease. Objective: This study was designed to clarify the various methods for diagnosis of Vascular dementia, as well as to identify the predictors of VD including the various risk factors, clinical features, neuropsychological criteria and neuroradiological findings of VD. Subjects and Methods: The study included 70 patients with cognitive deficit ( MMSE less than 17) of suspected Vascular dementia, with age above 60 years and 40 normal control subjects for those fulfilling the criteria of VD. All patients and control persons were subjected to: I. Thorough history taking, and clinical neurological examination II. Clinical assessment through the following scales: (a) Minimental State Examination, (b) DSM-IV for both Vascular Dementia and Alzheimer Dementia (c) Hachinski ischaemic scale, (d) Scales operationalized as research criteria 1. California Alzheimer s Disease Diagnostic and Treatment Centers (ADDTC) scale for Vascular Dementia, 2. National Institute of Neurological and Communicative Disorders and Stoke scale, for Alzheimer Dementia and related disorders association (NINCDs ADRDA) (e) Scales for assessment of specific aspects of dementia: 1. Hamilton depression scale 2. Columbia University scale, 3. Blessed dementia scale for assessment of daily activity and III. Neuroimaging studies including CT and/or MRI brain. Results: According to ADDTC scale and NINCDS-ADRDA and Hachinski ischemic scale, 40 patients (57.14%) were diagnosed as having Vascular dementia (32 patients fulfill the criteria of probable VD, and 8 patients fulfill the criteria of possible VD). Nineteen patients (27.14%) were diagnosed as having Alzheimer dementia. Eleven patients (15.72%) were diagnosed as having mixed dementia. According to DSM-IV, vascular dementia was diagnosed in (46 patients) 65.7%, while 24 patients (34.3%) were diagnosed as having Alzheimer dementia. MRI and CT were the most sensitive methods for diagnosing vascular dementia (96.5%) moreover, ADDTC scale was the most specific test (61%) for diagnosing VD. A statistically significant correlation was detected between increasing ages, duration of illness, and hypertension in addition to low education with VD. Conclusion: The association of proper clinical examination and neuropsychological scales specified for diagnosis of vascular dementia and MRI is crucial for diagnosis of vascular dementia. The highest specificity (72%) in diagnosis of vascular dementia was associated with using MMSE, DSM-IV, Hachinski and ADDTC suggesting that using more than 2 scales give more suitable chance for identifying the majority of patients with vascular dementia. (Egypt J. Neurol. Psychiat. Neurosurg., 2006, 43(1): ) INTRODUCTION Dementia refers to clinical syndrome of wide spread cortical dysfunction in a patient who remains alert with normal arousal 1. It is generally considered that Alzheimer s dementia is the most prevalent cause of dementia and vascular dementia is the second most common cause of dementia 2,3. Vascular dementia is the broad term for dementia associated with problems of the circulation of blood to the brain. It is also called "multi-infarct dementia" as the most common subtype under "Dementias Caused by Other Medical Conditions" in the DSM-IV system. It is the result of emboli to the brain, commonly referred to as "strokes," if they occurred on a detectable scale 4. Vascular dementia accounts for almost 20% of all cases of dementia, with at least another 20% of people having both Alzheimer s disease and vascular dementia. The annual incidence rates (per ) range from between

2 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (2) - July 2006 years of age and from 200 to 700 over 80 years and it is slightly more common in men than women 5,6,7. It is generally assumed that risk factors for Vascular Dementia (VaD) are those of stroke, with arterial hypertension as leading factor followed by atherosclerotic disease, orthostatic hypotension, low education level, alcohol abuse and heart disease 3. Fu et al. 8, reported that there is a paucity of accurate postmortem data pertinent to comorbid medical conditions in patients with dementia, usually in the form of amyotrophic lateral sclerosis, severe meningoencephalitis/ ventriculitis, probably secondary to seeding of the central nervous system by an infected cardiac valve. Combined neuropathological abnormalities (Alzheimer s disease plus another type of lesion, such as significant ischemic infarcts or diffuse Lewy body disease), normal pressure hydrocephalus and progressive supranuclear palsy. Other studies showed a higher proportion of lacunar strokes in Japanese population compared with white population which can be considered responsible for the increased prevalence of VaD in Japanese population. Diet, smoking, low education and low estrogen are of the main risk factors claimed for VaD nowadays 8,9,10. Circumstantial evidence suggests that VaD may be associated with cholinergic denervation. The specificity of this association has been difficult to assess because many of the patients are elderly and have the additional cholinergic lesions of aging and AD 11. The genetic factors blamed for VaD are going under the scope of genetic causes of stroke; CADASIL is highly linked to VaD depending on their charity in small vessel disease affiliction 12,13. Vascular dementia is due to the accumulation of multiple strokes in the brain. The strokes may not be obvious; they may only be detected by a brain image such as MRI or CT scan. The strokes usually are small, and accumulate in the white matter below the surface of the brain. This white matter is named so because it contains a white substance called myelin that insulates the nerve fibers interconnecting different brain regions. Hence, vascular dementia produces disconnections between different brain regions, resulting in a progressive decline of the affected brain functions. Vascular dementia often preferentially affects the frontal lobe, producing symptoms mediated by the frontal lobe including depression, poor judgment, and reduction in speech, attention problems, difficulty shifting between tasks, and difficulty performing complex tasks 14. SUBJECTS AND METHODS Subjects: This study included 70 demented patients with cognitive deficits according to Mini-Mental State Examination (had a score less than 17) of suspected vascular etiology with either (history of CVS, focal changes by clinical or radiological examination, cerebrovascular risk factors) age above 60 years and 40 control of cognitively normal persons of matched age and sex for those fulfilling the criteria of VaD. All patients were selected from Neurology Outpatient Clinic and Department, Kasr El-Aini Hospital, examined after at least 3 months of CVS, in which: All were Egyptians. Excluded from the study: * Patients with aphasia, severe hearing and visual impairment. * Patients with impaired conscious level, any medical or metabolic disease and their medication. * Patients with concomitant medical or metabolic illness known to affect cognition e.g. hypothyroidism, liver and kidney failure. * All cases with previous history of psychiatric disorders known to affect mentality e.g. major depression and schizophrenia. * Patients with psychoactive drugs or using drugs known to affect mentality e.g. anticholinergics, antiepileptics and antipsychotic. * Patients with history of head trauma with loss of consciousness. 410

3 Forayssa M. Talaat et al. Methods: All patients and control persons in this study were subjected to the following: I. Thorough history taking and neurological examination via the standardized Neurovascular sheet. II. Routine laboratory investigations; CBC, blood sugar estimation, renal functions, liver functions, uric acid evaluation and lipid profile assessment. III. Neuroimaging studies including CT and/or MRI. VI. Clinical and neuropsychological rating scales encompassing: A. Mini-Mental Scale Examination: For rapid screening of those with cognitive and/or intellectual deficit 15. It assesses orientation, short term memory, serial subtraction, constructional capacities and use of language. The total score is 30. A score of 24 is considered abnormal. A score of less than 17 is considered dementia B. Depression is tested by Hamilton Depression Scale 16 to exclude case of (pseudo-dementia). We included cases scoring less than 10 by Hamilton Depression Scale. C. Hachinski Ischaemic Scale (HIS) 17. To classify dementia into vascular, Alzheimer and mixed. The original scale consists of 13 items; each scale item was assigned a numeric value with double weighting applied to specific clinical features. - A score of 7 or more means vascular dementia. - A score of 0-4 means Alzheimer s dementia. - A score of 4-7 means mixed dementia. D. Scales formulated as a part of generalized diagnostic criteria for psychiatric disorders as DSM-IV: Diagnostic and statistical manual of mental disorders, fourth edition (DSM- IV) for diagnosis of VaD and AD are identical apart from requirement for the presence of evidence of CVD, either on clinical examination or neuroimaging and lack of progression in VD criteria 4. E. Scales operationalized as research criteria 1. ADDTC scale, 2. NINCDS ADRDA scale: - California Alzheimer Disease Diagnostic and Treatment Centers 18 (ADDTC) scale for further classification of VaD into definite, probable, possible. Which requires 1- Diagnosis of dementia: Cognitive decline (Loss of memory and deficits in at least two other domains. Excluding pre-existing mental impairment, delirium, altered state of consciousness. 2- Evidence of CVD: Presence of focal neurological signs. Brain CT or MRI required. 3- Dementia and CVD must be reasonably related. Sudden stepwise deterioration in cognitive abilities - National Institute of Neurological and Communicative Disorders and Stroke... The Alzheimer s disease and related disorders association (NINCDS-ADRDA) 19. It possesses a high degree of reliability in detecting and classifying dementia. Diagnosis of probable Alzheimer dementia requires: 1- Cognitive decline (Loss of memory and deficits in at least two other domains. Excluding preexisting mental impairment, delirium, altered state of consciousness. 2- Progressive deterioration in cognitive abilities. 3- Onset between ages 40 and 90 most often after age 65. F. Other neuropsychological scales to assess specific aspects in dementia: - Hallucinations, delusions, illusions and misidentifications are assessed by Columbia University Scale (CUSPAD) 20 for psychopathology in Alzheimer s Disease. - Daily activities by Blessed Dementia scale items are used to detect changes in daily performance, changes in habits and personality, interests and drive in demented patients. 411

4 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (2) - July 2006 Statistical Methods: Descriptive Statistics: mean±sd, number and percentage. * Analytic tests: unpaired t-test has been performed. * Pearson correlation coefficient(r) was done for all continuous data and the probability (p) was obtained from the tables according to the degree of freedom and so significance was calculated. * All tests were two sided and a P-value < 0.05 was considered significant. * All have been performed using SPSS ver.9. RESULTS This study was conducted on 70 patients with possibly vascular dementia (had a score below 17 by MMSE). 46 patients (65%) had vascular dementia and 24 patients (35%) had Alzheimer s dementia according to DSM-IV scales for dementia (Fig. 1). On the other hand, Hachinski ischemic score resulted in: 40 patients (57.41%) had vascular dementia, 19 patients (27.14%) had Alzheimer dementia and 11 patients (15.72%) had mixed dementia (Fig. 2). According to ADDTC scale 40 patients (57.14%) were diagnosed as having Vascular dementia (32 patients fulfill the criteria of probable VD, and 8 patients fulfill the criteria of possible VD). Most of the patients with vascular dementia had their age between years (75%). Their mean age±sd was 65.5±0.64. In addition, 62.5% (25 patients) were males and 37.5% (15 patients) were females. The distribution of 70 demented patients according to Hachinski ischemic score. Neurological deficits (ND) was detected by clinical examination in 100% of patients diagnosed as vascular dementia and only 10.5% of Alzheimer s dementia patients had ND. At the same time, 72.7% of mixed dementia patients had ND (Table 1). Different neuropsychological scales were used to assess demented patients due to vascular causes. A high statistically significant low mean of MMSE score results for (VaD) patients was present, when the results were compared to the control group. On the contrary, another high statistically significant high mean of the Blessed Dementia scale results was found in our patients as compared to the control group (Table 2). We tested VaD patients by many neuropsychological scales and we found that, 32 patients (80%) fulfilled the criteria of probable vascular dementia and 8 patients (20%) fulfilled the criteria of possible type, on the California Alzheimer Disease Diagnostic and Treatment Centers (ADDTC) scale. On the other hand, all patients (100%) had a score below 17 (demented) on MMSE. In Hashinski scale, all patients had score above 7. In Blessed Dementia scale, all patients had a score above 3. As well, regarding Columbia University Scale for Psychopathology in Alzheimer s disease (CUSPAD): 18 patients (45%) had hallucinations, 15 patients (37.5%) had delusions and 21 patients (52.5%) had misidentification (Table 3). Correlation of clinical variables to neuropsychological scales revealed that getting older, increasing duration of illness and decreased years of education were associated with decreasing scoring in MMSE. While a significant positive correlation (P<0.05) was noted between increasing age and duration of illness to scoring of Blessed scales (Table 4). The clinical presentation of 40 patients with vascular dementia demonstrated 100% motor affection mostly grade (4), 97.5% bladder disorder, 72.5% bulbar manifestations, 25% sensory deficit and 20% extrapyramidal manifestations. Moreover, 22.5% of patients had gait disorder Comparing the vascular risk factors in patients with vascular dementia to those of control subjects showed that, a highly significant difference was found between the 2 groups regarding hypertension, orthostatic hypotension, cardiac disease and diabetes mellitus. As well, another statistically significant difference was disclosed as regarding smoking and hypercholesterolemia (Table 5). All vascular dementia patients had positive radiological findings, while only 5 normal subjects had positive findings, which were 412

5 Forayssa M. Talaat et al. considered as a difference of high significant value (P<0.01). These were in the form of multiple lesions that were present in both sides mainly left, especially on the temporal, parietal and temproparietal regions, of which they were either deep lesions (50%) or cortical lesions (30%). In agreement with the presence of significant difference to lesions more than 1.5 cm and periventricular leukoencephalopathy (P<0.05). On the contrary, the positive findings found in the normal subjects that were of high significance single lesions mainly on the right side and the lesions were deep only (Table 6). On studying the relation between neuroradiological findings and results of neuropsychological scales in 40 patients with vascular dementia, we found that: As regards the site of the lesion, patients with lesions in the temporoparietal, T-P region had the lowest mean in MMSE scale, while it had the highest mean in the Blessed Dementia Scale. More important, regarding ADDTC scale; patients with probable VD dementia had lesions in the temporoparietal, occipital and frontal sites. Whilst, for Columbia scale, patients having delusions, hallucinations and misidentification showed 100% affection in the frontal region. Concerning the side of the lesion, MMSE had the lowest mean in left-sided lesions, so greater impairment of cognitive functions was observed. The reverse was for the Blessed Dementia Scale, where the highest means were observed in right side lesions. With reference to the ADDTC, all patients (100%) with right sided lesions were diagnosed as probable dementia. About the number of lesions, multiple lesions in radiology coincided with lowest means of MMSE scale and highest means of the Blessed Dementia Scale. Even more, all patients (100%) with multiple lesions were diagnosed as probable type by ADDTC. Regarding the size of the lesion the lowest means on MMSE were associated with large lesions, while on Blessed Dementia Scale, the highest mean was found in the large lesions. MMSE had the lowest mean in those with deep lesions with cortical extension and the reverse is again applied for the Blessed Dementia Scale that had its highest means in deep lesions only. Also, 100% of patients having a problem of misidentification (on Columbia scale) were shown to have deep lesions with cortical extension (Table 7). The sensitivity (which is the ability to detect the positive results) of different variables to detect vascular dementia was 97% for radiology,(mri). The specificity (which is the ability to exclude the negative results) was high with ADDTC(61%) and when all the scales were used (72%) (Fig. 3). 34% 66% Vascular dementia Alzheimer dementia Fig. (1): Distribution of 70 demented patients according to DSM-IV. 413

6 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (2) - July % 27% 57% Vascular dementia Alzheimer dementia Mixed dementia Fig. (2): Distribution of 70 demented patients according to Hachinski scale. Table 1. The presence of neurological deficits on clinical examination among demented patients according to Hachinski ischemic score. Neurological Vascular dementia(40) Alzheimer dementia(19) Mixed dementia(11) deficits No % No % No % With Without Table 2. Comparison between means ±SD of different neuropsychological scales in vascular demented patients and control groups. Neuropsychological scales VD Control subjects P-value MMSE Mean SD <0.01** Blessed Mean SD <0.01** **: Highly significant. 414

7 Forayssa M. Talaat et al. Table 3. Neuropsychological scales results in 40 patients with vascular dementia. Variable Number Percent MMSE Above Below Hachiniski ischemic scale < 4 and from > Blessed dementia scale ADDTC Probable Possible 8 20 CUSPAD Hallucination Delusions Misidentification Table 4. Correlation between different neuropsychological scales and age, duration of illness and duration of education in patients with vascular dementia. neuropsychological Age Duration of education Duration of illness scales r P-value r P-value r P-value MMSE <0.05* <0.05* <0.05* Blessed dementia scale <0.05* <0.05* <0.05* *: Significant Table 5. Comparison between vascular risk factors in 40 patients with vascular dementia and 40 normal control subjects. Risk Factors Vascular dementia patients (40) Control group patients (40) P-value No. % No. % Hypertension <0.01** Orthostatic hypotension <0.01** Smoking <0.05* Obesity >0.05 Cardiac disease <0.01** Diabetes Mellitus <0.01** Hypercholesterolemia <0.05* Hyperuricaemia >0.05 **: Highly significant. *: Significant. 415

8 Depth Size No Side Site Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (2) - July 2006 Table 6. Relation of neuro-radiological findings in patients with vascular dementia to normal controls. Neuro-radiological Positive findings Vascular dementia (40) Control group (40) P-value No. % No. % single <0.01** Number multiple <0.01** Side left <0.01** right <0.01** both <0.01** Depth cortical <0.01** Deep only <0.01** both <0.01** Location Frontal <0.05* parietal >0.05 temporal <0.05* temporoparietal >0.05 occipital >0.05 Size cm >0.05 More than 1.5 cm <0.05* Periventricular leukoencephatholpathy both > <0.05* Table 7. Relation between the neuro-radiological findings and results of neuropsychological scales in 40 patients with vascular dementia. Neuropsychological Scales Neuro-radiological MMSE Blessed ADDTC CUSPAD Findings Probable Possible Hallucination Delusions Misidentification M SD M SD No. % No. % No. % No. % No. % Parietal (12) Temporal (14) Tempro-parietal (8) Occipital (4) Frontal (2) Left (13) Right (5) Both (22) Single (10) Multiple (30) cm (20) >1.5 cm (12) Both (8) Cortical (12) Deep (20) Both (8)

9 Forayssa M. Talaat et al. Specifity Sensitivity All scales Radiology ADDTC Hachinski scale DSM-IV MMSE Clinical EX Fig. (3): The sensitivity and specificity of clinical examination, all scales and radiological examination. DISCUSSION Developments in the past three decades have led to a radical rethinking of the association between cerebrovascular disease (CVD) and dementia, and set the stage for a reconceptualisation of dementia from vascular causes 22. There are two obvious steps in the diagnosis of VaD, first; diagnosis of dementia per se and then, establishment of its vascular etiology. Dementia is defined as a multifaceted decline in cognitive functioning causing impaired functioning in daily life. Impairment of memory is generally regarded as a necessary aspect, but decline in one or more other cognitive domains (i.e., language, praxis, gnosis, visuoconstructive function, frontal-executive functions) must also be demonstrated 23. What constitutes significant vascular etiology is not always easy to establish. Recent studies using magnetic resonance imaging (MRI) of the brain have reported periventricular hyperintensities on T 2 -weighted images, arguably vascular in origin, in up to 93% of healthy elderly individuals, so guidelines for determining the significance of cerebral vascular lesions are needed 24. Using the rapid screening MMSE for diagnosis of cognitive impairment, seventy patients with cognitive deficit (MMSE less than 17) were selected from the outpatient clinic of suspected Vascular dementia with either history of cerebrovascular risk factors or CVS with age above 60 years. This result was in accordance with Folestein et al. 15, who reported that MMSE is a good rapid and reliable examination for detecting impaired cognitive function. There are inconsistencies in published reports regarding the profile of cognitive impairments in vascular dementia, and its differentiation from Alzheimer's disease. However, subcortical vascular dementia and Alzheimer's disease produce distinctive profiles of cognitive impairment which can act as an adjunct to diagnosis 25,26. In the present work, by means of DSM-IV used for diagnosis of Alzheimer s 417

10 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (2) - July 2006 dementia and vascular dementia, 46 patients (65%) fulfilled the criteria for vascular dementia, while 24 patients (34%) satisfied the criteria for Alzheimer s dementia. This was in contrast to many studies who reported that Alzheimer dementia is the most prevalent cause of dementia and vascular dementia is the 2 nd most common type However, this was explained in our study by the method of selection of patients in our neurological clinics concentrating on patients with vascular dementia. This was in conformity with many reports 28,29. Furthermore, in our study, on applying Hachinski ischemic scale for dementia patients, 40 patients (57.14%) were diagnosed as vascular dementia, 19 (27.14%) as Alzheimer type and 11(15.72%) were of mixed type of dementia. So, Hachinski ischaemic scale gained a wide acceptance for use for clinical evaluation of patients with dementia, harmoniously with many reports that stated the same results 30,31. Moreover, applying ADDTC for vascular dementia on the 70 patients with cognitive decline, 40 patients (57.14%) were diagnosed as having Vascular dementia (32 patients fulfill the criteria of probable VD, and 8 patients fulfill the criteria of possible VD). Considering the presence of neurological deficits among all our 70 patients; 50 patients (71.4%) had neurological deficits, while 20 patients (28.6%) were free. What is more important, that all cases of vascular dementia had neurological deficits (100%), in addition to 8 patients (72.7%) of those having mixed dementia, conversely to Alzheimer s dementia in which only 2 patients (10.5%) had neurological deficits. This fact was in accordance with reports of different studies stating that focal neurological deficit is a cardinal feature of vascular dementia, and asserting that the presence of focal neurological symptoms and /or signs is an important item for differentiation of Alzheimer from vascular dementia 31. Barbra et al. 7, reported that not all individuals with stroke develop dementia therefore it is important to determine the risk factors for ischaemic vascular dementia. In the present study, a highly significant correlation between the increasing age of demented patients and neuropsychological and cognitive impairment as proved by lower means in MMSE scores and higher means in Blessed Dementia Scale scoring. Many other studies enlightened increasing age as the most important risk factor for both stroke and dementia 32,33. More important, in our study, a significant difference between vascular dementia patients and control group was detected as regards the level of education. With reference to the illiterate group, being more in those with dementia and those who achieve high school level being more in those without dementia. However, although patients having a university level education were slightly more in those without dementia, they showed no statistical difference. These results denote that low level of education or fewer years of education is a risk factor for vascular dementia. Many authors were in agreement with this, explaining it by the fact that many years of education likely relates to larger function cognitive reserve and thus a greater ability to remain functionally competent despite an increasing burden of cerebrovascular insult among patients with more education 10,33,34. Many vascular risk factors seems to be a risk for developing vascular dementia 35. Ischemic damage to the subcortical white matter of the brain, referred to as leukoaraiosis, which is a frequent complication of hypertension-related microvascular disease and contributes to the risk of stroke and vascular dementia 35,36. In our study, a highly significant statistical difference in the presence of hypertension and orthostatic hypotension between patients and control group was found. While hypertension increases the risk of vascular dementia, high systolic blood pressure may serve a protective role once dementia has set in as hypertension maintains perfusion to relatively ischaemic areas 37. Moreover, lower blood pressure values and more orthostatic hypotension have been related to the severity of dementia, yet, this relationship is still controversial

11 Forayssa M. Talaat et al. Epidemiologic evidence has suggested that diabetes mellitus significantly increases risk for the development of vascular dementia independent of vascular risk factors. As insulin's role as a neuromodulator in the brain has been described, its significance for dementia has also emerged. Insulin dysregulation may contribute to dementia pathology through several mechanisms including decreased cortical glucose utilization particularly in the hippocampus and entorhinal cortex; increased oxidative stress through the formation of advanced glycation end-products; increased Tau phosphorylation and neurofibrillary tangle formation; increased b-amyloid aggregation through inhibition of insulin-degrading enzyme. A high statistically significant difference was noted in our study between vascular dementia patients and controls in the presence of diabetes mellitus 39. In accordance to previous study 40, we found that cardiac disease and hypercholesterolemia were significantly correlated to vascular dementia. Regarding the radiological features predicting VaD, the present study revealed that demented patients with left sided lesions showed lowest mean of score of MMSE and highest mean score for Blessed Dementia Scale; an observation which high lightened the role of left sided lesions as a predictor for VaD. This was supported by Pohjasvaara et al. 41, and Censori et al. 42, who reported the importance of left sided lesion for development of VD and post stroke dementia. On the other hand right sided lesions were found more in normal control. Furthermore, Tatemichi et al. 24, reported that the pathophysiologic mechanisms of VaD are due to the volume of cerebral injury with infarct size reaching a critical threshold overcoming the brain s compensatory capacities. In concordance with our study; we found that large and multiple lesions were significantly increased in VaD patients who had more cognitive impairment proved by the scores of MMSE and Blessed Dementia Scale. Pertaining to the location and depth of the lesions, the present study revealed that lesions located in the temporal lobe are significantly related to the development of VaD and have worse means in the MMSE scores coinciding with more cognitive impairment. As well, all VaD patients who had frontal lobe lesions had hallucinations and delusions. This was in line with Tatemichi et al. 24, who suggested that certain association areas as angular gyrus or inferomesial Temporal lobe lesion or frontal lobe ones are especially associated with dementia. In association to Roman et al. 43 and Sitoh et al. 44, who reported that infarction of certain strategic areas may be crucial in development of vascular dementia. Concerning sensitivity and specificity of different neuropsychological scales in diagnosing vascular dementia; we found that DSMIV Scale, MMSE, and Hachinski scale had a high sensitivity. This was in agreement to Holmes et al. 45, who reported that Hachinski scale may be suitable for identifying the majority of patients having vascular dementia, its only drawback is lacking neuroimaging criteria, considering that the highest sensitivity for diagnosing vascular dementia was radiological findings (97%) in our study. In the present work ADDTC test shows a high specificity for diagnosing VaD (61%), this was in agreement with Amar et al. 23 and Ryding 46, who reported that ADDTC criteria exhibited a higher specificity compared with Hachinski Ischaemic Scale in diagnosing vascular dementia. The highest specificity in spotting cases of vascular dementia was associated with using MMSE, DSM-IV, Hachinski Ischaemic Scale and ADDTC (72%). This was in agreement with Berg et al. 47, who reported that using more than 2 scales give more suitable chance for identifying the majority of patients with vascular dementia. REFERENCES 1. American Psychiatric Association (1987): Diagnostic and statistical manual of mental disorders, 3 rd edition. (revised). Washington, DC. 2. Gold G, Giannakopoulous P, Paixao-Montes C, Herrmann FR, Mulligan R, Michel JP and Beuras (1997): Sensitivity and specificity of newly proposed clinical criteria for possible vascular dementia. Neurology; 49:

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14 Egypt J. Neurol. Psychiat. Neurosurg. Vol. 43 (2) - July , ,