Outcome measures for the study of activities of daily living in vascular dementia.

Decline in functional abilities is a major component of the dementia syndrome. The definition of dementia in the International Classification of Diseases (10th rev.) requires a cognitive impairment sufficient to impair personal activities of daily living (ADL). The Diagnostic and Statistical Manual of Mental Disorders (4th ed.) also requires cognitive deficits sufficiently severe to cause impairment in occupational or social functioning and must represent a decline from a higher level of functioning. However, the term disability is more appropriate than impairment to describe a loss in activities, as opposed to a loss of elementary functions, and is consistent with World Health Organization definitions of impairment, disability, and handicap. There is no doubt that ADL outcomes are required in therapeutic drug studies on vascular dementia, and there is a good rationale and some evidence for the use of ADL scales developed for therapeutic research in Alzheimer disease, favoring scales devoid of items sensitive to physical disabilities. Similarly, ADL-related clinical milestones could be used for longer-term studies aiming predominantly at slowing progression of disease in both early and later stages of dementia. Slower decline in ADL and delay in reaching ADL-related clinical milestones should be considered as valid outcomes by regulatory bodies in the process of dementia drug approval.

Clinical trials of propentofylline in vascular dementia. European/Canadian Propentofylline Study Group.

The neuroprotective glial cell modulator propentofylline has been used in clinical trials involving more than 800 patients with vascular dementia (VaD). These data derive from two sources: a pooled group of VaD patients from four early phase III European trials, and a multinational European/Canadian phase III study (MN 305) that features a combined randomized withdrawal/delayed onset of progression design to evaluate the effect of propentofylline on disease progression. In the pooled studies, DSM-III-R criteria, Hachinski Ischemia Scores, computed tomography (CT), and magnetic resonance imaging (MRI) were used to select subjects with mild-to-moderate disease; in MN 305, National Institute of Neurological Disorders and Stroke/Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) criteria and neurologic examinations (including CT and MRI scans) were used to select patients with possible or probable VaD. The use of a central rater to assess cerebrovascular disease in neuroradiologic examinations for study MN 305 was considered to be a key feature for reducing the heterogeneity of the VaD patient population. In addition, the inclusion of patients with possible VaD in this trial greatly increased the number of eligible patients; subgroup analyses revealed no substantial differences between patients with probable versus possible VaD, justifying their inclusion in the study. VaD patients exhibited a more pronounced placebo response in global assessments compared with the Alzheimer disease population in a parallel study. In addition, they experienced less deterioration over time with respect to cognitive and global assessments. Beneficial effects of propentofylline were consistently demonstrated in the domains of cognitive and global function for both VaD populations; however, no treatment benefits could be demonstrated for activities of daily living, possibly due to factors relating to the study population/design, the lack of a validated test instrument for such patients, the caregiver-related phenomenon of "tutoring," or the nature of the disease itself.

Propentofylline in the treatment of vascular dementia and Alzheimer-type dementia: overview of phase I and phase II clinical trials.

Pathophysiologic processes common to both vascular (multi-infarct) dementia and dementia of the Alzheimer type may include microglial activation with resultant generation of inflammatory cytokines and neurotoxic free radicals, decreased secretion of nerve growth factor by astrocytes, excess release of glutamate with associated neurotoxicity, and loss of cholinergic neurons. The functional benefits and neuroprotective effects of propentofylline (PPF) stem from its interference with these overlapping pathways of neurodegeneration. The clinical pharmacology and safety of PPF were studied in a number of phase I studies in healthy young and elderly adults and in patients with renal or hepatic impairment. These studies have shown that PPF 300 mg t.i.d. is safe and well tolerated when taken on an empty stomach 1 h before meals. In a randomized, double-blind phase II study involving 190 elderly subjects with clinically and psychometrically documented mild to moderate dementia, 12 weeks of PPF therapy produced significantly greater improvements than placebo in Gottfries-Bråne-Steen (GBS) scores, Mini-Mental State Examination (MMSE) scores, and Clinical Global Impression (CGI) ratings. A subsequent phase II study using positron emission tomography (PET) revealed that cortical glucose metabolism improved significantly in patients with vascular dementia after 12 weeks of PPF treatment but deteriorated significantly with placebo. A third phase II study, which enrolled patients with Alzheimer-type dementia, demonstrated that PPF significantly enhanced functional reserve, as reflected by increases in regional cerebral glucose metabolism after stimulation with a verbal memory task. In contrast, patients randomized to placebo exhibited a significant decline in functional activation and significant worsening in their MMSE scores over the course of this 12-week study. Propentofylline proved to be safe, well tolerated, and free of severe side effects in all three of these phase II trials. Phase I trial results suggest that significant food interactions occur with PPF, indicating that the drug should be taken on an empty stomach 1 h before meals. Phase II trial results indicate that PPF yields clinically measurable improvements in the symptoms of dementia and prevents loss of stimulation-related increases in glucose metabolism over a treatment period of 3 months. Whether these results indicate that PPF can slow the progression of dementia can be determined only by long-term trials specifically designed to determine the drug's effect on disease progression.

Propentofylline in the treatment of Alzheimer's disease and vascular dementia: a review of phase III trials.

Propentofylline, a neuroprotective glial cell modulator, has been shown in preclinical studies to address some of the common pathological processes of Alzheimer's disease (AD) and vascular dementia (VaD), including glial cell activation and increased production of cytokines, free radicals, and glutamate. To examine whether propentofylline (300 mg t.i.d. taken 1 h before meals) would provide beneficial effects in patients with AD and/or VaD, 901 patients with mild-to-moderate AD and 359 patients with mild-to-moderate VaD were enrolled in four double-blind, placebo-controlled, randomized studies ranging in duration from 6 months to 56 weeks. Propentofylline was found to provide consistent improvements over placebo in efficacy assessments for both AD and VaD patients. In addition, results from a drug withdrawal study suggested that propentofylline does not merely relieve dementia symptoms but slows the progression of the disease itself. Propentofylline had a good safety profile and was generally well tolerated.

Propentofylline enhances cerebral metabolic response to auditory memory stimulation in Alzheimer's disease.

To evaluate efficacy, safety, metabolic and clinical effects of propentofylline in Alzheimer's disease (AD), a prospective, randomized, double-blind, placebo-controlled trial was performed in 30 patients with mild to moderate AD who underwent pretreatment and posttreatment 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography under resting conditions and during stimulation with an auditory memory paradigm. Twenty-eight subjects completed the 3-month study. The drug was well tolerated. In the active treatment group, a significant increase of cerebral metabolic response to the memory task was observed (multiple measurement ANOVA P = 0.02). The placebo group showed a significantly decline in the MMSE score (P = 0.02) while there was no change in the treatment group. This suggests a protective role for propentofylline in slowing the progression of AD.

Clinical trial designs for demonstrating disease-course-altering effects in dementia.

Advances in our understanding of the pathogenesis of Alzheimer disease (AD) and vascular dementia (VaD) now permit responsible discussion of therapies that may go beyond relief of cognitive and behavioral symptoms and actually slow progression of disease. The mechanisms of neuronal death and the pathologic role of glia are being elucidated, and epidemiologic studies have suggested potential protective value for anti-inflammatory drugs, estrogen, and free-radical scavengers. However, demonstrating disease-modifying drug effects for progressive conditions such as dementia can be a daunting task, fraught with clinical, statistical, and ethical dilemmas. To evaluate trial designs for demonstrating such effects, the International Working Group on Harmonization of Dementia Drug Guidelines (IWG) conducted a symposium at the Sixth International Congress on Alzheimer's Disease and Related Disorders, held July 1998 in Amsterdam. The presentations at the IWG symposium covered the two basic designs currently being used in clinical trials, survival analysis and staggered-start/withdrawal, in addition to clinical data generated from the National Institute on Aging Alzheimer's Disease Cooperative Study vitamin E/selegiline trial in patients with AD and the phase III clinical studies of propentofylline in patients with AD and VaD. It is hoped that this article will open a dialogue among investigators and regulatory authorities regarding appropriate trial designs to support a regulatory claim for disease-modifying effects.

Clinical trials in dementia with propentofylline.

The mode of action of propentofylline (a xanthine derivative) suggested that it would have beneficial effects in patients with Alzheimer's disease or vascular dementia. In four double-blind, placebo-controlled, randomized studies, 901 patients with mild to moderate Alzheimer's disease and 359 patients with mild to moderate vascular dementia were treated for up to 12 months (daily dose of propentofylline: 3 x 300 mg taken 1 hr before food). Patients were assessed at regular intervals for efficacy and safety of the drug. Efficacy variables covered cognitive and global functions as well as activities of daily living. Propentofylline showed statistically significant, clinically relevant improvements over placebo in efficacy assessments, both in patients with Alzheimer's disease and in patients with vascular dementia. The drug was also well tolerated. It had no significant effects on laboratory findings and the adverse events that were considered to be related to the study medication were mostly minor, transient, and affected the digestive and nervous systems.

A 12-month, randomized, placebo-controlled trial of propentofylline (HWA 285) in patients with dementia according to DSM III-R. The European Propentofylline Study Group.

Alzheimer's disease (AD) and vascular dementia (VaD) share several features such as overactivation of microglial cells, damage induced by free radicals, glutamate and calcium overload. Propentofylline (HWA 285) has shown beneficial effects on all of these common elements, thus favouring its use in both subtypes of dementia. In a multinational, randomized, 12-month, double-blind, parallel-group study 260 out-patients with mild to moderate AD or VaD received 300 mg propentofylline (n = 129) or placebo (n = 131) three times daily 1 h before meals. The efficacy was tested at four independent rater levels (physician, psychologist, relative and patient) with assessments covering three major domains of dementia (global function, cognitive function and activities of daily living). After 12 months, the total patient population showed statistically significant treatment differences in favour of propentofylline for the global measures of dementia (Gottfries-Bråne-Steen scale, GBS, p = 0.001; Clinical Global Impressions, CGI, item I: p = 0.004, item II: p = 0.072) as well as for the cognitive measures (Syndrome Short Test, SKT, p = 0.002) and Mini-Mental State Examination (p = 0.001). The activities of daily living also showed a significant treatment difference in favour of propentofylline (p = 0.002). No significant treatment differences were found for rating scales performed by the patients. At month 12, VaD patients showed treatment differences in favour of propentofylline for the GBS total score (p = 0.006), CGI item I (p = 0.004), GGI item II (p = 0.044) and SKT (p = 0.028). Treatment differences for AD patients were all in favour of propentofylline and reached statistical significance for the SKT (p = 0.018). Propentofylline showed a good safety profile with respect to adverse events, vital signs, ECG and laboratory changes.

Propentofylline improves regional cerebral glucose metabolism and neuropsychologic performance in vascular dementia.

In a double-blind, placebo-controlled trial in thirty patients with mild to moderate vascular dementia (VD) according to DSM-III-R criteria, the effects of the adenosine uptake blocker propentofylline (HWA 285) on regional cerebral glucose metabolism (rCMRGl) was studied using positron emission tomography of 2-[18F]fluoro-2-deoxy-D-glucose (FDG). 25 subjects completed the 3-months study. Propentofylline significantly improved relative rCMRGl in the motor cortex, while relative rCMRGl in the placebo treated group worsened significantly. Neuropsychologically, visual information processing was improved in the propentofylline group and we observed a trend towards a slowing of the progression of cognitive deterioration in patients with VD. The results of the longitudinal analysis showed further that neuropsychological and metabolic changes are closely related. These findings justify a large-scale clinical trial to prove therapeutic efficacy.

HWA 285 (propentofylline)--a new compound for the treatment of both vascular dementia and dementia of the Alzheimer type.

The pharmacological profile of HWA 285 favors its use in patients with both Alzheimer's disease (PDD) and/or vascular dementia (MID). Clinical trials showed clinically relevant, statistically significant efficacy in the domains of cognitive function, global function and activities of daily living (ADL) in both PDD and MID. HWA 285 had a prolonged symptomatic effect for at least 12 months, although therapeutic effects were seen already after the first 3 months of treatment. HWA 285 was very well tolerated for at least 1 year.

Effect of propentofylline on regional cerebral glucose metabolism in acute ischemic stroke.

In a randomized double-blind placebo-controlled study in 30 patients with acute ischemic stroke, the effect of the adenosine uptake blocker propentofylline on regional brain glucose metabolism (rCMRglu) was investigated using repeated positron emission tomography (PET) with 2-[18F]fluoro-2-deoxy-D-glucose (FDG). Treatment was initiated within 48 h after onset of symptoms. The clinical course was followed for 3 months. In the propentofylline group, after 14 days rCMRglu was increased in the infarct by 37.3% and was practically unchanged in other brain regions, whereas in the control group glucose metabolism had decreased in all regions (1.4-13.4%). These differences were significant between the two groups [Analysis of variance (ANOVA) p = 0.005]. Although there was a trend toward greater clinical improvement in the propentofylline-treated patients, this did not reach statistical significance. The results correspond to experimental data showing that propentofylline improves energy metabolism in cerebral ischemia. A clinical trial is needed to determine whether this new therapeutic principle can be successfully used in acute human stroke.

Rating scales and computed tomography in multi-infarct dementia.

Forty patients who fulfilled the DSM-III-R criteria for multi-infarct dementia and had a score of 7 points or more on Hachinski ischemia score (HIS) were analyzed with the purpose to correlate the rating scales and CT scans. Among the examined patients there were 32 women with the average age of 68.5 +/- 9.8 years and 8 men with the average age of 68.8 +/- 10.4 years. No significant difference between sex in relation to Folstein Mini-mental state examination (MMSE), Gottfries-Brane-Steen scale (GBS) and Sandoz clinical assessment-geriatric scale (SCAG) was found. There is no correlation of GBS and SCAG on MMSE. With regression analysis a good correlation was found between GBS and SCAG, and we suggest that in such studies only one of these two scales is sufficient. CT abnormalities were found in about 77% of examined patients without difference according to sex. But, GBS score demonstrated greater disability among MID patients with abnormal CT scans than in MID patients with normal CT scans. In medical history of male MID patients completed stroke was significantly more common than among women, while the female MID patients had in their history significantly more frequent transient ischemic attack (TIA). This finding should be checked in a greater patient population. It is stressed that in everyday clinical practice it is necessary to use the diagnosis of multi-infarct dementia, e.g. to differentiate cerebral diseases according to etiology and pathogenesis.

PC12 cells: a model system for studying drug effects on dopamine synthesis and release.

PC12 cells were used as a model system to examine drug effects on dopamine synthesis and release. It could be demonstrated that KCl treatment induced release of endogenous dopamine, simultaneously DOPA synthesis was increased. Despite of the increase in DOPA synthesis the intracellular concentration of tetrahydrobiopterin (the co-factor of tyrosine hydroxylase) remained stable, indicating that the catalytic recycling of the used tetrahydrobiopterin is much more rapid than the tetrahydrobiopterin consumption by tyrosine hydroxylation. Reserpine induced a decrease of intracellular dopamine but no dopamine reached the extracellular space, instead all dopamine was depleted into the cytoplasma and metabolized to DOPAC. Nitrendipine had no effect on intracellular dopamine storage, Bay K 8644 induced a small decrease of intracellular dopamine and a small increase in DOPA production. N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide (W7) induced a reserpine-like depletion at concentrations above 1 X 10(-6) M. The KCl-induced dopamine release and the stimulation of DOPA production were blocked by 1 X 10(-7) M nitrendipine and enhanced by 1 X 10(-7) M Bay K 8466, whereas 1 X 10(-6) M W7 had no effect on both parameters. These findings were compared to data obtained in other tissues reported in the literature indicating that PC12 cells are a useful model for studying drug effects on catecholamine synthesis and release.

Apomorphine does not decrease tissue levels of tetrahydrobiopterin in vivo.

It was reported that R(-)apomorphine and other catechols are potent inhibitors of dihydropteridine reductase in vitro. It was suggested that decreased levels of tetrahydrobiopterin may represent a mechanism by which R(-)apomorphine inhibits catecholamine synthesis in vivo. This paper demonstrates that tetrahydrobiopterin levels are not affected either in vitro (PC12 cells) or in vivo (rat liver and corpus striatum) by treatment with R(-)apomorphine, whereas DOPA (3,4-dihydroxyphenylalanine) production (PC12 cells, corpus striatum) is reduced. This indicates that R(-)apomorphine does not inhibit DOPA production by reducing 6(R)-L-erythro-tetrahydrobiopterin) levels.

Direct inhibition of tyrosine hydroxylase from PC-12 cells by catechol derivatives.

Several drugs with a catechol moiety were studied for their potency to inhibit tyrosine hydroxylase (TH) from PC-12 cells in vitro. When the natural compounds tested were compared, dopamine, norepinephrine and 2(3,4-dihydroxyphenyl)-ethanol (DOPET) were most effective (IC50 between 1.4 and 3.6 microM with 0.5 microM 6(R,S)-L-erythro-5,6,7,8-tetrahydrobiopterin as cofactor). 3,4-Dihydroxyphenylalanine (DOPA; IC50: 35 microM) and 3,4-dihydroxyphenylacetic acid (DOPAC; IC50: 180 microM were less potent inhibitors. Among the synthetic drugs possessing catechol moiety, isoproterenol, (+/-)-2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (6,7-ADTN) and (+/-)-2-dimethylamino-6,7-dihydroxy-tetrahydronaphthalene (TL-99) had the same inhibitory effects as the natural catecholamines (IC50 between 1.6 and 3.9 microM), whereas the apomorphine derivatives and 2,3,4,5-tetrahydro-1-phenyl-1 H-3-benzazepine-7,8-diol (SKF 38393) were even more potent (IC50: 0.5-0.8 microM). These results demonstrate that natural catechols and certain drugs (e.g. 6,7-ADTN, TL-99, SKF 38393) are more effective direct blockers of tyrosine hydroxylase than generally assumed provided appropriate assay conditions are used. In the case of dopamine and norepinephrine, these findings suggest a reevaluation of their role for feedback control of tyrosine hydroxylase in vivo.

Effects of apomorphine enantiomers and of lisuride on 3,4-dihydroxyphenylalanine production in striatal synaptosomes.

The effects of lisuride and of the R(-)- and S(+)-enantiomers of apomorphine were examined on 3,4-dihydroxyphenylalanine (DOPA) production by striatal synaptosomes and by crude, soluble striatal tyrosine hydroxylase. Due to their catechol structure, the enantiomers were almost equally effective in blocking soluble tyrosine hydroxylase (EC 1.14.16.2) (IC50 = 470 and 890 nM for R(-)- and S(+)-apomorphine, respectively), provided incubations were performed at pH 7.2 with 1 mM tetrahydrobiopterin as cofactor. The enantiomers were similarly effective in blocking synaptosomal DOPA production (IC50 = 410 and 970 nM for R(-)- and S(+)-apomorphine, respectively). As S(+)-apomorphine but not R(-)-apomorphine is considered to be a dopamine antagonist, these results support the assumption that the block of synaptosomal DOPA production by both apomorphine enantiomers is due to a direct inhibition of tyrosine hydroxylase. Lisuride at high concentrations (10-100 microM) blocked DOPA production in striatal synaptosomes; simultaneously, intrasynaptosomal dopamine was depleted. These data support the assumption that lisuride inhibits DOPA production indirectly, similar to reserpine. In accordance with this assumption, lisuride was without effect on DOPA production in dopamine-depleted synaptosomes. These results demonstrate that inhibition of synaptosomal DOPA production by at least some dopamine agonists may be explained by direct inhibitory effects on tyrosine hydroxylase.

Effect of apomorphine, alpha-methylparatyrosine, haloperidol and reserpine on DOPA production in clonal cell lines (PC-12 and N1E-115).

The effect of various drugs on DOPA production in the pheochromocytoma clone PC-12 and the neuroblastoma clone N1E-115 was studied. The N1E-115 cells contain only very low amounts of dopamine due to a lack of the aromatic L-amino acid decarboxylase, whereas the PC-12 cells are rich in dopamine. alpha-Methyl-p-tyrosine and apomorphine blocked DOPA production in both cell clones. Reserpine and haloperidol reduced the intracellular dopamine in the PC-12 cells and simultaneously induced a blockade of cellular DOPA production. The released dopamine was primarily recovered as 3,4-dihydroxyphenylacetic acid indicating a release of dopamine into the cytoplasm. This transient increase of cytoplasmic dopamine by reserpine or haloperidol brings about the inhibition of DOPA production in the PC-12 cells. Our results show that the PC-12 clone especially reacts to various drugs like other in vitro systems and may serve as an additional model for studying drug effects on catecholamine biosynthesis and metabolism.

Evaluation of neurotropic drug actions on tyrosine hydroxylase activity and dopamine metabolism in clonal cell lines.

Two clonal cell lines (the pheochromocytoma clone PC-12 and the neuroblastoma clone N1E-115) were used to compare direct and indirect drug effects on tyrosine hydroxylase and dopamine turnover. Both clones contain the cofactor of tyrosine hydroxylase, tetrahydrobiopterin, in sufficient concentrations. 2,4-Diamino-6-hydroxy-pyrimidine (DAO-Pyr), an inhibitor of GTP cyclohydrolase, which is the rate-limiting enzyme in tetrahydrobiopterin biosynthesis, lowers DOPA production indicating that cofactor supply is a limiting factor for catecholamine synthesis. DOPA synthesis in the PC-12 cells can be stimulated by incubation with the natural cofactor tetrahydrobiopterin, but also by its possible precursors sepiapterin and dihydrobiopterin or the analogs methyl-tetrahydropterin and dihydropterin. The regulating enzyme for DOPA synthesis, tyrosine hydroxylase, can be inhibited by certain drugs either directly or indirectly by increasing dopamine concentrations in the cytoplasm after release from its vesicular stores. Using the neuroblastoma clone N1E-115 which lacks DOPA decarboxylase and thus contains only low levels of dopamine the site of action of certain drugs could be determined. Drugs affecting the tyrosine hydroxylase directly (alpha-methyl-para-tyrosine, apomorphine) decreased DOPA production in both clones, while drugs acting via interference with the vesicular stores (reserpine, amphetamine, nigericin) were effective only in the PC-12 cells. After total depletion of dopamine by nigericin at high concentrations or long-term incubation with 3-hydroxybenzyl-hydrazine (NSD 1015), DOPA production increased in the PC-12 cells indicating a usually occurring regulation of tyrosine hydroxylase by cytoplasmic dopamine. Dopamine concentration in the cytoplasm was calculated to be in the range of 1 X 10(-6) mol/l.(ABSTRACT TRUNCATED AT 250 WORDS)