Acetylcholinesterase inhibitors reduce spreading activation in dementia.

Alzheimer's disease is associated with degeneration of the cholinergic system, which affects memory and attention functioning. Acetylcholinesterase inhibitors (AChEI) have been found to increase attention and given this effect might reduce spreading activation of memory nodes in lexical/semantic networks. We sought to determine whether this effect of AChEIs existed in a group of patients with dementia. A mixed sample of 34 patients with dementia (17 taking AChEIs and 17 not taking these medications) were administered the Controlled Oral Word Association Test and the Animal Naming Test. The average word frequency for their responses was obtained and used as a measure of spreading activation. Patients taking AChEIs had a significantly higher average word frequency for the COWAT as compared to those not taking AChEIs. No difference was found for the average word frequencies for the AN test. Administration of AChEIs appears to reduce spreading activation, possibly due to cholinergic innervations of the frontal cortex.
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