Dementia of the Alzheimer type

Canine inherited ataxia

A previously unrecognized canine disorder consists of familial cortical cerebellar degeneration with many characteristics that are similar to inherited ataxias in humans. The disease occurs in Gordon setters and appears to be inherited as an autosomal recessive trait. The dogs appear normal during the first 6 months of life, but between 6 and 12 months of age they develop a broad-based gait and dysmetria, followed by truncal ataxia. Nystagmus occurs late. The disorder is slowly and insidiously progressive. Neuropathological examination shows atrophy of the cerebellar cortex, particularly the pars intermedia. There is loss of Purkinje and granule cells, more severe in older dogs. Other parts of the neuraxis appear normal. These pathological changes resemble those of the familial human cerebellar cortical atrophies.

Cortical somatostatin-like immunoreactivity in cases of Alzheimer's disease and senile dementia of the Alzheimer type

The activity of choline acetyltransferase (ChAT) and the concentration of somatostatin-like immunoreactive material (SLI) have been measured in 8 brain regions from 12 normal individuals and 12 cases of presenile and senile dementia of the Alzheimer type. ChAT activity was significantly lower in all 8 brain regions of demented patients and the SLI concentration was significantly reduced in 7 of the the 8. There were correlations between the extent of the reductions of ChAT activity and SLI concentration in four brain regions, and a greater reduction of parietal cortex SLI in younger patients than in the more elderly.

Reduced amounts of immunoreactive somatostatin in the temporal cortex in senile dementia of Alzheimer type

Post-mortem brain tissue from 15 patients dying with a diagnosis of senile dementia of Alzheimer type (SDAT) was compared with tissue obtained from 16 control patients at routine post-mortem. A significant fall in choline acetyltransferase (ChAT) activity was observed in the cortex, hippocampus and amygdala of the SDAT cases and was maximal in the temporal cortex. The fall in ChAT activity observed in the temporal cortex was accompanied by a significant reduction (47%) in immunoreactive somatostatin.

Reduced somatostatin-like immunoreactivity in cerebral cortex from cases of Alzheimer disease and Alzheimer senile dementa

Both Alzheimer's disease and senile dementia of the Alzheimer type (AD/SDAT) are progressive dementias characterized neuropathologically by the presence in the cerebral cortex of numerous neurofibrillary tangles and neuritic plaques. We use the abbreviation AD/SDAT to denote all such cases, irrespective of age of onset. Studies of neurotransmitter-related parameters in autopsied brain tissues from patients with AD/SDAT have, to date, been confined to five putative transmitter systems. Acetycholine-releasing neurones seem to be most markedly and consistently affected, as judged by the extensive reductions in choline acetyltransferase (ChAT) and acetylcholinesterase activities that have been reported. Despite numerous studies, there is no consistent evidence for the involvement of neurones releasing dopamine, noradrenaline, serotonin, or gamma-aminobutyric acid in AD/SDAT, nor for loss of muscarinic cholinergic receptors. Thus, the involvement of cholinergic neurones in AD/SDAT seems to be specific. However, the possible involvement of neurones using other chemicals as transmitters has yet to be explored. The recent recognition of the existence of so-called 'peptidergic neurones' in the mammalian brain (for review see ref. 8) and the availability of radioimmunoassay (RIA) techniques for studying these peptides, have led us to begin a systematic investigation of neuropeptides in autopsied brain tissue from cases of AD/SDAT, and from neurologically normal individuals. We report here results obtained with a RIA for somatostatin, showing that somatostatin-like immunoreactivity in the cerebral cortex is reduced in tissue from AD/SDAT patients.