Ulla Passant

Prevalence of dementia subtypes: A 30-year retrospective survey of neuropathological reports

We investigated the distribution of neuropathologically defined dementia subtypes among individuals with dementia disorder. The neuropathological reports were studied on all patients (n=524; 55.3% females; median age 80, range 39-102 years) with clinically diagnosed dementia disorder who underwent complete autopsy including neuropathological examination within the Department of Pathology at the University Hospital in Lund, Sweden, during the years 1974-2004. The neuropathological diagnosis was Alzheimers disease (AD) in 42.0% of the cases, vascular dementia (VaD) in 23.7%, dementia of combined Alzheimer and vascular pathology in 21.6%, and frontotemporal dementia in 4.0% of the patients. The remaining 8.8% of the patients had other dementia disorders, including combinations other than combined Alzheimer and vascular pathology. The registered prevalence of dementia subtypes depends on many variables, including referral habits, clinical and neuropathological judgments and diagnostic traditions, all of these variables potentially changing over time. This, however, does not seem to obscure the delineation of the major dementia subgroups. In this material of 30 years from Lund in the south of Sweden, AD by far dominated among dementia subtypes, while cerebrovascular pathology corresponded with the dementia disorder, either entirely or partly, in almost half of the demented patients.

Cerebrospinal fluid neurofilament light chain protein levels in subtypes of frontotemporal dementia

BackgroundFrontotemporal dementia (FTD) is recognised as a clinically and morphologically heterogeneous group of interrelated neurodegenerative conditions. One of the subtypes within this disease spectrum is the behavioural variant FTD (bvFTD). This is known to be a varied disorder with a mixture of tau-positive and tau-negative underlying pathologies. The other subtypes include semantic dementia (SD), which generally exhibits tau-negative pathology, and progressive non-fluent aphasia (PNFA), which is usually tau-positive. As the clinical presentation of these subtypes may overlap, a specific diagnosis can be difficult to attain and today no specific biomarker can predict the underlying pathology. Neurofilament light chain protein (NFL), a cytoskeletal constituent of intermediate filaments, is thought to reflect neuronal and axonal death when appearing in the cerebrospinal fluid (CSF). NFL has been shown to be elevated in CSF in patients with FTD compared with AD and controls. Our hypothesis was that the levels of NFL also differ between the subtypes of FTD and may indicate the underlying pathological subtype.MethodsWe retrospectively analysed data from previous CSF analyses in 34 FTD cases (23 bvFTD, seven SD, four PNFA), 20 AD cases, and 26 healthy controls. A separate group of 10 neuropathologically verified and subtyped FTD cases (seven tau-negative, three tau-positive) were also analysed.ResultNFL levels were significantly higher in FTD compared with both AD (p<0.001) and controls (p<0.001). The NFL levels of SD and bvFTD were significantly higher (p<0.001) compared with AD. The biomarker profiles of PNFA and AD were similar. In the neuropathologically verified FTD cases, NFL was higher in the tau-negative than in the tau-positive cases (exact p=0.017).ConclusionsThe marked NFL elevation in some but not all FTD cases is likely to reflect the different underlying pathologies. The highest NFL values found in the SD group as well as in the neuropathologically verified tau-negative cases may be of subtype diagnostic value, if corroborated in larger patient cohorts. In bvFTD, a mixture of tau-positive and tau-negative underlying pathologies could possibly explain the intermediate NFL values.

Decreased monoamine metabolites in frontotemporal dementia and Alzheimer’s disease

The concentrations of the monoamine metabolites homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (HMPG) in the cerebrospinal fluid (CSF) of patients with clinical frontotemporal dementia (FTD; n = 30), early onset Alzheimers disease (EAD; n = 33), late onset Alzheimers disease (LAD, n = 27) and normal controls (n = 31) were determined using HPLC. ANCOVA showed no significant effect of neuroleptic medication, extrapyramidal signs, myoclonia or gender on the CSF levels of the monoamine metabolites. Homovanillic acid was significantly reduced in all diagnostic groups (FTD, p = 0.0002; EAD, p = 0.016; LAD, p = 0.013). 5-Hydroxyindoleacetic acid was significantly reduced in EAD (p = 0.013) and in LAD (p = 0.0014), and HMPG was reduced in LAD only (p = 0.020). HMPG was significantly higher in FTD compared to EAD (p = 0.0005) and LAD (p = 0.0003). CSF-5-HIAA was significantly reduced in patients with antidepressant medication (p = 0.006). ANCOVA within the FTD group showed no significant effect of neuroleptic or antidepressant medication, extrapyramidal signs, myoclonia, gender or FTD subtype on the CSF levels of the monoamine metabolites. The results suggest that CSF-HMPG might differentiate FTD from EAD and LAD, but not from normals.

Orthostatic hypotension in organic dementia: relationship between blood pressure, cortical blood flow and symptoms

Regional cerebral blood flow was measured in 35 patients with organic dementia (Alzheimers disease, n=13, vascular dementia, n=17, frontotemporal dementia, n=5) and orthostatic hypotension. Measurements were performed during supine rest and during head-up tilt (60°). Despite marked blood pressure falls, few patients had symptoms of orthostatic hypotension. All three dementia groups had a decrease in regional cerebral blood flow in the frontal lobes during head-up tilt, but no change in mean hemispheric flow. All patients had a consistent drop in their systolic blood pressure upon head-up tilt, with a wide variation over time. The findings suggest that orthostatic hypotension needs to be considered, and actively sought for, in organic dementia as many patients may lack the typical symptoms of orthostatic hypotension, despite a marked fall in blood pressure.

Neuropsychological Findings in Frontal Lobe Dementia

Neuropsychological investigations were performed on 18 patients with a clinical diagnosis of frontal lobe dementia supported by regional cerebral blood flow measurements. Nature and degree of cognitive impairment were examined with a comprehensive test battery. The results of the neuropsychological assessment could be described as three levels of cognitive impairment. The increasing levels of cognitive impairment were accompanied by corresponding levels of reduced cerebral blood flow in frontotemporal areas. No apparent relationship emerged between impairment level and illness duration, indicating a considerable individual variation in the clinical course of frontal lobe dementia.

Absolute quantification of cerebral blood flow in normal volunteers: correlation between Xe-133 SPECT and dynamic susceptibility contrast MRI.

To compare absolute cerebral blood flow (CBF) estimates obtained by dynamic susceptibility contrast MRI (DSC‐MRI) and Xe‐133 SPECT.

Psychiatric symptoms and their psychosocial consequences in frontotemporal dementia.

Based on a retrospective study of 19 neuropathologically verified cases with frontotemporal dementia (FTD), neuropsychiatric symptoms related to behavioral disturbances and their psychosocial consequences were studied. The results indicate that frontotemporal dementia is often misdiagnosed early in the clinical course. Behavioural features with impaired social interactions, impaired personal regulation, and loss of insight were seen in all patients. The psychosocial consequences reported in this paper challenge future research in frontotemporal dementia.

A novel tau mutation in exon 9 (1260V) causes a four-repeat tauopathy

A novel mutation in exon 9 of tau, I260V, is associated with a clinical syndrome consistent with frontotemporal dementia with extensive tau pathology; however, neurofibrillary tangles and Pick bodies are absent. Significantly, Sarkosyl-insoluble tau extracted from affected brain tissue consisted almost exclusively of four-repeat isoforms. Consistent with these findings, in vitro biochemical assays demonstrated that the I260V mutation causes a selective increase in tau aggregation and a decrease in tau-induced microtubule assembly with four-repeat isoforms only. The contrasting pathology and biochemical effects of this mutation suggest a different disease mechanism from the other exon 9 mutations and demonstrates the critical role for the first microtubule-binding domain in tau-promoted microtubule assembly and the pathogenic aggregation of tau.

A Clinico-Pathological Study of Heart and Brain Lesions in Vascular Dementia.

All vascular dementia (VaD) cases, neuropathologically verified in a longitudinal prospective dementia project, were classified according to the vascular brain lesion type and related to the dementia type and cardiovascular pathology. From 1976 to 1995, there were 175 VaD cases, 49 of which were pure, without Alzheimer pathology and only one type of cerebrovascular lesion. Furthermore, it was found that 6 cases suffered hypoxic hypoperfusive disease, while 7 were found to have large vessel disease and 36 small vessel disease. In addition to Alzheimer pathology, more than one type of vascular brain pathology was found in the remaining 126 cases. In these cases, diagnosed in accordance with the predominant type of VaD, hypoxic-hypoperfusive lesions were found in 55, large vessel lesions in 50 and small vessel lesions in 110 cases. It should be stressed that 87% of all cases with hypoxic hypoperfusive lesions also had Alzheimer pathology. Cardiovascular and aortic pathologies were more prevalent in small vessel dementia than in the other VaD groups. Clinically diagnosed arterial hypertension was significantly associated with small vessel dementia, but not with hypoxic-hypoperfusive dementia. Cardiovascular symptoms varied considerably in frequency between different dementia groups. VaD is a heterogeneous group regarding lesions caused by different pathophysiological mechanisms and with different combinations of brain pathologies. It is therefore necessary to identify the various types of vascular brain lesions for a correlation with clinical symptoms and for diagnostic purposes in the search for risk factors and therapeutic strategies.

Functional imaging of the frontal lobes in organic dementia. Regional cerebral blood flow findings in normals, in patients with frontotemporal dementia and in patients with Alzheimer's disease, performing a word fluency test

Patterns of functional cortical activation were studied by means of regional cerebral blood flow measurements, performed during rest and during a word fluency task in normal subjects (n = 22), in patients with Alzheimers disease (n = 17), and in patients with frontotemporal dementia (n = 15). Although all groups showed a significant activation of the Brocas area during word production, the activation of the dorsolateral prefrontal cortex was clearly subnormal in both dementia groups. The frontal dysfunction was not explained by number of words produced, illness duration, or age. Thus, the results demonstrate that the word fluency task is a sensitive measure of frontal lobe function, and its incorporation in imaging studies may facilitate the detection of subtle functional impairment of the frontal lobes in organic dementia.