Tetrahydroaminoacridine (THA) in Alzheimer's disease: An assessment of attentional and mnemonic function using CANTAB

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Abstract
A placebo‐controlled cross‐over trial (n=89) investigated the use of a chronic dose of the cholinesterase inhibitor THA, as a treatment for dementia of the Alzheimer type (DAT). Effects on both subjective clinical rating scales and objective computerised tests were assessed. In regard to the former, analysis of the three main clinical outcome measures showed statistically significant effects of the drug on the Mini‐Mental State Examination (MMSE) and the Abbreviated Mental Test Score (AMTS), but not on the Activities of Daily Living scale (ADL). Using the objective computerised CANTAB tests, sensitive to specific aspects of memory and attention, evidence was found for improvements in attentional function rather than memory, in patients with mild to moderate DAT. Although these improvement: were significant, they were small and restricted to certain tests of attentional function. Nevertheless, they add to the growing body of evidence that the cholinergic system is involved in the control of attentional processes: and are substantiated by the findings of a second study examining the effects of an acute dose of nicotine on attentional and mnemonic performance in patients with DAT. This study found significant improvements in cognitive performance in patients receiving nicotine, in objective tests of attention but not of short‐term memory. These data will clearly provide important comparative data for future investigations of putative cognitive enhancing drugs in DAT sufferers.