TETRAHYDROAMINOACRIDINE (THA) IN ALZHEIMERS-DISEASE - AN ASSESSMENT OF ATTENTIONAL AND MNEMONIC FUNCTION USING CANTAB

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 clini cal rating scales and objective computerised tests were assessed. In r egard to the former, analysis of the three main clinical outcome measu res showed statistically significant effects of the drug on the Mini-M ental State Examination (MMSE) and the Abbreviated Mental Test Score ( AMTS), but not on the Activities of Daily Living scale (ADL). Using th e objective computerised CANTAB tests, sensitive to specific aspects o f memory and attention, evidence was found for improvements in attenti onal function rather than memory, in patients with mild to moderate DA T. Although these improvements were significant, they were small and r estricted to certain tests of attentional function. Nevertheless, they add to the growing body of evidence that the cholinergic system is in volved in the control of attentional processes; and are substantiated by the findings of a second study examining the effects of an acute do se of nicotine on attentional and mnemonic performance in patients wit h DAT. This study found significant improvements in cognitive performa nce in patients receiving nicotine, in objective tests of attention bu t not of short-term memory. These data will clearly provide important comparative data for future investigations of putative cognitive enhan cing drugs in DAT sufferers.