Senile dementia of the Alzheimer type treated with aniracetam: a new nootropic agent

Autonomic consequences of brainstem infarction

OBJECTIVE

It is well known that patients with brainstem infarctions sometimes experience dizziness, vertigo and falls, although the exact mechanism is not clear. Therefore, we designed a study to quantify autonomic function in patients with brainstem infarction.

PATIENTS AND METHODS

We examined autonomic function in 15 patients with brainstem infarctions, who had a history of vertigo, nausea, floating sensation and/or general fatigue during standing, and 31 age-matched controls using the composite autonomic scoring scale (CASS), which was used to grade autonomic function. The patients underwent initial autonomic assessment and then were subjected to aniracetam therapy. The drug was given orally (dose of 600 mg/day) for a duration of 56 days. Upon completion of aniracetam administration, the CASS was again tested.

RESULTS

Upon initial assessment, the patients had mild reductions in mean blood pressure (MBP) and lack of an increasing heart rate (HR) within 5 min of head up-tilt, an impairment in BP correction during late phase II and reduced phase IV beat-to-beat BP response to the Valsalva maneuver, and reduced heart rate response to deep breathing (HRdb). CASS indicated mild autonomic dysfunction. After 8 weeks of treatment with aniracetam, the patients' symptoms improved and the autonomic tests showed improvement in autonomic function.

CONCLUSION

Part of the pathogenesis of recurrent vertigo or dizziness with brainstem infarction might be due to mild autonomic dysfunction. Aniracetam, which activates the cholinergic system in brain, might correct the cardiovagal system in these patients. The CASS may be a sensitive tool for assessing mild autonomic dysfunction in patients with brainstem infarction.

Wandering behaviors in institutionalized persons with dementia

1. Etiological factors that have been identified in relation to wandering include mental impairment, confusion, darkened or unfamiliar environment, boredom, stress, tension, anxiety, lack of control, lack of exercise, diseases of the central nervous system and cardiac decompensation. 2. The findings of this pilot study indicate that in structured settings such as SCUs, behaviors appear to be related to activities in the environment, e.g., quiet behaviors at night and more active behaviors during the day. 3. Psychotropic medications may not have the desired effect on behaviors in patients with Alzheimer's disease, however, nursing interventions geared toward modifying the environment may be useful in shaping behaviors of patients with dementia.

Pharmacotherapy of cognitive impairment in Alzheimer's disease: a review

Experimental pharmacotherapy of cognitive impairment in Alzheimer's disease has seen a recent proliferation of drug trials involving a wide variety of drugs. Many of the earlier studies focused on cholinergic agents. However, subsequent advances in basic and biological sciences have broadened the scope of therapeutic strategies beyond the neurotransmitter approaches to include neurotrophic, metabolic-enhancing, membrane-modifying, and antitoxic agents, and have also provided rationale for developing antiamyloid and anti-infective therapies. For the clinician, it has not been easy to keep abreast of these developments. In this article, I present an overview of the cognition-enhancing drugs that have been used in the past, of those currently under investigation, and of new drugs and strategies that are likely to receive attention in the next few years.

Piracetam and other structurally related nootropics

Nearly three decades have now passed since the discovery of the piracetam-like nootropics, compounds which exhibit cognition-enhancing properties, but for which no commonly accepted mechanism of action has been established. This review covers clinical, pharmacokinetic, biochemical and behavioural results presented in the literature from 1965 through 1992 (407 references) of piracetam, oxiracetam, pramiracetam, etiracetam, nefiracetam, aniracetam and rolziracetam and their structural analogues. The piracetam-like nootropics are capable of achieving reversal of amnesia induced by, e.g., scopolamine, electroconvulsive shock and hypoxia. Protection against barbiturate intoxication is observed and some benefit in clinical studies with patients suffering from mild to moderate degrees of dementia has been demonstrated. No affinity for the alpha 1-, alpha 2-, beta-, muscarinic, 5-hydroxytryptamine-, dopamine, adenosine-A1-, mu-opiate, gamma-aminobutyric acid (GABA) (except for nefiracetam (GABAA)), benzodiazepine and glutamate receptors has been found. The racetams possess a very low toxicity and lack serious side effects. Increased turnover of different neurotransmitters has been observed as well as other biochemical findings, e.g., inhibition of enzymes such as prolylendopeptidase. So far, no generally accepted mechanism of action has, however, emerged. We believe that the effect of the racetams is due to a potentiation of already present neurotransmission and that much evidence points in the direction of a modulated ion flux by, e.g., potentiated calcium influx through non-L-type voltage-dependent calcium channels, potentiated sodium influx through alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor gated channels or voltage-dependent channels or decreases in potassium efflux. Effects on carrier mediated ion transport are also possible.

Advances in the pharmacotherapy of Alzheimer's disease

The authors reviewed the literature on the agents proposed for the treatment of Alzheimer's disease (AD). Different classes of drugs have been tested for this indication including psychostimulants, anticoagulants, vasodilators, hyperbaric oxygen, hormones, nootropics, cholinomimetics, monoaminergics and neuropeptides without conclusive evidence of being beneficial for the treatment of this condition. Among the cholinomimetics recent research data seems to indicate that they might produce modest benefits in mild-to-moderate AD patients. Recently, other drugs have also been proposed including neurotrophic factors, phosphatidylserine, angiotension [corrected] converting enzyme (ACE) inhibitors, calcium channel blockers, acetyl-L-carnitine, xanthine derivatives, anti-inflammatory agents, aluminum chelate agents, and D-cycloserine. Of these new strategies few hold promise of more substantial benefits for AD, with the possibility of altering the course of the disease, but these drugs await confirmatory trials.

Elevated corticosteroid levels block the memory-improving effects of nootropics and cholinomimetics

Oral pretreatment of mice with aldosterone or corticosterone blocked the memory-enhancing effects of piracetam, pramiracetam, aniracetam and oxiracetam in a dose-related manner, without, however, impairing the animals' learning performance. The improvement of memory induced by physostigmine, arecoline, and tacrine (THA) was similarly inhibited. The fact that elevated steroid levels suppress the memory-enhancing effects of entirely different substances could indicate that these substances have a common site of action. In the light of new observations showing increased cortisol concentrations in Alzheimer patients, this steroid dependency of the effects of memory enhancers might explain why only a limited number of these patients respond to therapy with nootropics or cholinomimetics.

Effect of piracetam administration on 3H-N-methylscopolamine binding in cerebral cortex of young and old rats

Piracetam, a nootropic drug, has been used for some time in Alzheimer's disease for its facilitatory effect on learning and memory. Rats treated with piracetam (500 mg/kg, p.o.) daily, during 1 and 2 weeks, showed a significant increase in muscarinic receptor number (Bmax) and in the dissociation constant values (Kd) in the cerebral motor cortex, in binding studies using 3H-NMS as ligand. The effect was observed not only in young rats (control- Bmax = 663.4 fmol/mg protein, Kd = 0.45 nM; treated- Bmax = 961.9 fmol/mg protein, Kd = 0.82 nM) but also in aged animals (control- Bmax = 628.0 fmol/mg protein, Kd = 0.47 nM; treated-Bmax = 747.6 fmol/mg protein, Kd = 0.84 nM). Since piracetam does not interact with muscarinic receptors, the reason for its effect expressed as the enhanced number of brain muscarinic receptors is not clear but could be the result of stimulation of phospholipid synthesis and thus would represent an indirect action of the drug.

Diagnostic and pharmacological approaches in Alzheimer's disease

Alzheimer's disease is a chronic progressive disease affecting higher intellectual functioning. The clinical diagnosis is made when the onset of illness is insidious, the course slowly progressive and all the treatable causes of dementia have been ruled out. The use of more stringent criteria has improved clinical diagnosis, but at best only 80% of patients are accurately diagnosed. Ultimately the diagnosis depends upon pathological confirmation. The neuritic plaques and neurofibrillary tangles described by Alzheimer, although not pathognomonic for the disease, continue to be the basis for pathological diagnosis. The aetiology and pathophysiology of Alzheimer's disease are presently unknown. Epidemiological studies have suggested a genetic basis for the disorder, and many biochemical studies have linked it to degeneration of central cholinergic neurons, and possibly to abnormalities of other neurotransmitter systems. A marker which would permit accurate diagnosis early in the course of disease would be of major importance to researchers and clinicians alike. No marker has been found to date, although recent research results are promising. Various pharmacological strategies have been employed in the treatment of Alzheimer's disease. More recently attempts have focused on enhancing central cholinergic transmission. Despite the well-founded rationale for these studies, results have been modest.

Aldosterone receptors are involved in the mediation of the memory-enhancing effects of piracetam

The blockade of the memory-enhancing effects of piracetam resulting from adrenalectomy can be abolished by substitution with either corticosterone or aldosterone. However, corticosterone substitution does not reinstate these effects if the aldosterone receptors are blocked by the aldosterone antagonist epoxymexrenon.

Aniracetam tested in chronic psychosyndrome after long-term exposure to organic solvents. A randomized, double-blind, placebo-controlled cross-over study with neuropsychological tests

In order to examine if the nootropic drug, aniracetam, was capable of improving cognitive performance, 44 subjects suffering from chronic psychosyndrome after long-term exposure to organic solvents were included in a randomized, double-blind, placebo-controlled, cross-over study. The treatment periods were 3 months with aniracetam 1 g daily and 3 months with placebo. Neuropsychological tests as well as a physical and neurological examination were performed at entry into the study and after each treatment period, together with an evaluation of the subjects' overall condition. Neither the doctors' nor the subjects' own assessment of the overall condition indicated that the trial medication had had any effect. No significant changes in neuropsychological symptoms were observed. A statistically significant difference in favour of antiracetam was found in only 1 of the 19 neuropsychological test measures, namely a test for constructional ability. However, in another test on visuo-spatial function, a statistically significant result was found in favour of placebo. Thus, aniracetam was found to be ineffective in the treatment of subjects suffering from chronic psychosyndrome after long-term exposure to organic solvents.

The use of a scopolamine model to study the potential nootropic effects of aniracetam and piracetam in healthy volunteers

In this study 26 healthy volunteers received scopolamine 0.7 mg subcutaneously on seven occasions at least a week apart. Cognitive efficiency was measured with a test battery before and 60 min following scopolamine on each occasion. Following this, over the seven occasions, a range of oral and intravenous dose regimens were administered including aniracetam 2 mg intravenously, 100 mg intravenously, 200 mg intravenously, 1500 mg per os and piracetam 2400 mg per os. On each session the test battery was then performed again at 120 and 200 min following scopolamine. The seven treatments were administered double- blind and the order was counterbalanced between volunteers over visits using a Latin Square design. At 60 min, scopolamine produced marked and significant decrements in all of the measures of memory and information processing. Aniracetam 1500 mg was able to sig nificantly antagonize decrements on both memory and information processing tasks. The other active treatments also produced significant effects, but for two these were equal to, and for two slightly above, the number which may have occurred by chance, and thus were questionable. Overall, the findings demonstrate that aniracetam 1500 mg can antagonize cognitive decrements produced by cholinergic blockade in healthy volunteers, and suggest that the drug possesses nootropic properties.

The hyperventilation-induced ischaemia model in human neuropharmacology: neurophysiological and psychometric studies of aniracetam and 3-OH aniracetam

Standardized hyperventilation in young subjects induces changes in the EEG, a decrease in the velocity of the cerebral blood flow and a decline in cognitive performance, which are comparable to those occurring in patients with cerebral ischaemia. The anti-ischaemic properties of aniracetam and 3-OH aniracetam were tested in this model. A single oral dose of 3-OH aniracetam 1500 mg appeared to have the most pronounced effect on hyperventilation-induced EEG changes and cognitive deterioration. The test drugs had no effect on the heart rate or blood flow velocity. The effects agree with those of other drugs classified as noötropics.

The safety and lack of efficacy of vinpocetine in Alzheimer's disease

Fifteen Alzheimer patients were treated with increasing doses of vinpocetine (30, 45, and 60 mg per day) in an open-label pilot trial during a one-year period. Patients were assessed seven times both on and off drug with: the Buschke Selective Reminding Task, a letter fluency test, a category fluency test, the Boston Naming Test, a cognitive capacity screening examination, and a clinical global impression. Vinpocetine failed to improve cognition on psychometric testing or overall functioning, as measured by the clinical global impression, at any dose tested. Patients showed significant decline in most measures during the course of the study, at the same rate as a matched control group, consistent with progressive dementia. There were no significant side effects from drug therapy. We conclude that vinpocetine is ineffective in improving cognitive deficits and does not slow the rate of decline in individuals with Alzheimer's disease.

Cognitive enhancing agents: current status in the treatment of Alzheimer's disease

Extensive recent literature on drugs used to enhance cognitive functioning, reflects the growing social problem of dementia. Many clinical trials have been undertaken with variable success. In most cases the disorder studied has been Alzheimer's disease. The pharmacological approach has been designed to rectify the presumed pathophysiological processes characteristic of the condition. Agents tested include cerebral vasodilators, cerebral metabolic enhancers, nootropics, psychostimulants, neuropeptides and neurotransmitters with a special emphasis on drugs used to enhance cholinergic function. Ethical and practical issues concerning clinical drug trials in dementia will be discussed.