Heterogeneity in dementia of the Alzheimer type: evidence of subgroups

We reviewed records of 121 consecutive patients with dementia of the Alzheimer type. Patients with myoclonus or extrapyramidal signs had greater intellectual decline and functional impairment in daily activities. Among patients studied over 4 years, there were four groups: benign--little to no progression; myoclonic--severe intellectual decline and frequent mutism after younger onset; extrapyramidal--severe intellectual and functional decline and frequent psychotic symptoms; typical--a gradual progression of intellectual and functional decline, but without other distinguishing features. Except for the group with myoclonus, no subgroup was segregated by age at onset or other demographic variables. This study suggests that dementia of the Alzheimer type is heterogeneous, and that certain clinical manifestations may be useful in predicting outcome.

Reaction time and vigilance in Parkinson's disease. Possible role of altered norepinephrine metabolism

Delayed reaction time and diminished vigilance have been observed in Parkinson's disease (PD) but have not been related to biochemical changes in the disease. As norepinephrine is reduced in the brain in PD and this neurotransmitter has been related to attention and learning, we investigated the relationship of neuropsychological measures, including those of reaction time and vigilance, to the norepinephrine metabolite 3-methoxy - 4 - hydroxyphenethyleneglycol (MHPG) in 39 patients with idiopathic PD. The MHPG levels correlated with a measure of general intellectual ability and with performance on reaction time and continuous performance tasks. Our data suggest that altered norepinephrine metabolism may contribute to some aspects of intellectual dysfunction in PD.

Contribution of perceptual motor dysfunction to construction and tracing disturbances in Parkinson's disease

Patients with Parkinson's disease and controls traced patterns of increasing complexity presented on a vertical transparent screen. Some patterns were presented with missing segments which subjects were required to fill in. Digitising equipment quantitated movements for computer analysis. Subjects also completed a brief test of general intellectual function, a construction test and an assessment for depression, and the severity of patients' Parkinsonian signs and symptoms was rated. Patients performed more poorly than controls on complete patterns, and their errors increased more sharply than controls on patterns with missing segments. Patients' errors, but not those of controls, in filling in missing segments were uniquely related to performance on construction tasks. Other aspects of patients' tracing performance correlated with the severity of their Parkinsonian symptoms. These findings suggest that there is an underlying perceptual motor deficit in Parkinson's disease that affects performance on both tracing and construction tasks.

Altered serotonin metabolism in depressed patients with parkinson's disease

Depression is a common symptom in patients with Parkinson's disease. It is not related to the severity of the motor symptoms or changes in dopamine metabolism and does not improve on treatment with dopamine agonists. Alterations in serotonin metabolism are found in primary (endogenous) depression. The brain content of serotonin in Parkinson's disease is also reduced, but this has not been related to any manifestation of the disorder. We found that the CSF content of the major metabolite of serotonin, 5-hydroxyindoleacetic acid, was lower in depressed than in nondepressed parkinsonians. The data suggest that the alterations in serotonin metabolism in Parkinson's disease identify a subgroup of patients who are prone to depression.

Pergolide therapy for Parkinson's disease: neurobehavioral changes

Pergolide mesylate, a long-acting dopamine agonist, is effective in treating Parkinson's disease. Behavioral change is said to be one adverse effect. We therefore studied 19 parkinsonian patients with neuropsychological tests before and after initiating pergolide therapy. Intellectual and behavioral changes were also monitored clinically for up to 2 years. There was no decline in performance on the neuropsychological tests. Six patients had transient psychiatric or intellectual changes that were controlled by reducing drug dosage. These changes were similar to those seen with other dopamine agonists.

Functional asymmetry of the amine transporter from chromaffin granules

The studies presented in this communication describe the existence of a pH-dependent kinetic barrier in amine translocation in membrane vesicles isolated from chromaffin granules from bovine adrenal medulla. This barrier prevents efflux of amines previously accumulated in the membrane vesicles. In these preparations, once the amine is accumulated, there is no further need for ATP. This would suggest a low permeability of the membrane, both to ions and to the amine. In addition, we show that under conditions which thermodynamically favour efflux this is kinetically blocked. This block is due to a rapid protonation of the transporter in the interior of the vesicle. Net efflux can be induced by agents that bring upon an alkalinization of the internal pH such as ammonium salts or nigericin. On the other hand, the rate of exchange with extravesicular substrate is almost identical at the various pH values tested. The physiological implications of this mechanism are discussed.

Is "subcortical dementia" a recognizable clinical entity?

The concept of "subcortical dementia" is controversial, lacking clinical validation and having only a questionable pathological basis. Over 100 patients with Alzheimer's, Parkinson's or Huntington's disease, subdivided into three functional disability stages, were given a brief quantitative neuropsychological assessment. Patients with Huntington's or Parkinson's disease were less intellectually impaired than those with Alzheimer's disease at each functional stage. Criteria for dementia were present in all of the Alzheimer's patients but in only half of the Huntington's and Parkinson's disease groups. Patients with similar overall intellectual function scores had no distinct pattern of neuropsychological test performance. Depression, absent in patients with Alzheimer's disease, was present in half the patients with Huntington's and Parkinson's disease and was correlated with intellectual decline. The concept of subcortical dementia is misleading. The pattern of neuropsychological impairment is not distinct, and the neuropathological basis of dementia in these diseases may result from a combination of cortical and subcortical degeneration.

Perceptual motor dysfunction in Parkinson's disease: a deficit in sequential and predictive voluntary movement

We studied the ability of Parkinsonian patients and controls to generate voluntary movements on a tracing task. Subjects were videotaped while tracing designs of increasing complexity, presented on a vertical, transparent screen. Some designs were presented in a degraded form and subjects filled in their missing sections. Subjects also received a constructional task and a test of general intellectual ability. The quality of errors on the tracing task differed in the Parkinsonian and control groups. Parkinsonian patients made two distinct types of errors. One probably related to the motor disorders of the disease, but another seemed to be related to a higher level of control over sequential and predictive movements. The latter correlated with performance on the constructional and general intellectual tasks. These results suggest that Parkinson's disease may affect basal ganglia structures that are necessary for voluntary movements which require sequencing or planning. Clinically this may be observed in perceptual motor tasks since they require both voluntary movement and sequential organisation of behaviour.

Depression, intellectual impairment, and Parkinson disease

To determine the prevalence of depression in Parkinson disease (PD) we evaluated 55 consecutive patients without dementia and 31 of their spouses. All subjects completed the Beck depression inventory and a quantitative mini-mental state examination. Using the Beck criteria, 47% of the patients and 12% of the spouses rated themselves as significantly depressed. Mental state scores were significantly lower in the patients. There was a correlation between the severity of depression and cognitive impairment, particularly for calculation, digit span, and visuomotor skills. The severity of parkinsonism, particularly bradykinesia, also paralleled cognition. There was a slight but significant relationship between parkinsonism and depression. These results confirm the high incidence of depression in PD, and suggest that depression in Parkinson patients may be accompanied by mild intellectual impairment and inattention which is independent of the severity of the illness.