Faculty Bibliography

The effects of acute lorazepam challenges on plasma (p) HVA, MHPG, and 5-HIAA, and their relationship to drug-induced cognitive and motor deficits and the apolipoprotein (APOE)-epsilon4 allele were examined. Eighteen healthy elderly (8 epsilon4 carriers) received placebo or acute oral lorazepam doses (0.5 mg or 1 mg) in random sequence, 1-week apart. Cognitive assessment and plasma levels of pHVA, pMHPG, and p5-HIAA were determined at baseline and at 1, 2.5, and 5 h postchallenge. There was no drug-to-placebo difference in monoamine levels and no consistent relationship between changes in monoamine levels and cognitive performance, regardless of epsilon4 status. However, the 1.0 mg dose increased p5-HIAA in epsilon4 carriers, whereas it caused a reduction in noncarriers. Higher baseline pMHPG and p5-HIAA levels were associated with better baseline memory. The epsilon4 allele may modulate the effect of lorazepam on p5-HIAA, but further studies are needed to confirm this finding and elucidate its possible significance

Benzodiazepines (BZPs) have been shown to reduce hypothalamic-pituitary-adrenal (HPA) axis activity acutely in normal humans. In contrast, the effects of chronic BZP treatment on the HPA axis have not been well studied, especially in the geriatric population. This study examined the acute and chronic effects (3 weeks) of alprazolam and lorazepam on plasma cortisol in 68 subjects (60-83 years) who received 0.25 or 0.50 mg b.i.d. alprazolam, or 0.50 or 1.0 mg b.i.d. lorazepam, or placebo orally according to a randomized, double-blind, placebo-controlled parallel design. Memory assessment and blood samples for plasma cortisol were obtained prior to the morning dose on days 0, 7, 14, and 21, and at 1, 2.5, and 5 h postdrug on days 0 and 21. Assessments of anxiety and depression were carried out at days 0, 7, 14, and 21 before drug administration. Plasma cortisol was affected compared to placebo only by the 0.5 mg alprazolam dose. During the first and the last day of treatment, there was a significant drop in cortisol at 2.5 h after alprazolam compared to placebo. The predose cortisol levels increased significantly during chronic alprazolam treatment, and correlations were found between these cortisol changes and changes in depression, anxiety, and memory scores. These findings suggest that even a short period of chronic treatment with alprazolam, but not lorazepam, may result in interdose HPA axis activation in the elderly, consistent with drug withdrawal. If confirmed, this effect may contribute to an increased risk for drug escalation and dependence during chronic alprazolam treatment

The degree to which elderly adults experience cognitive impairments from centrally acting anticholinergic drugs is variable, but the cause of this variability is unknown. The present study examined the epsilon4 allele as a possible modulator of the effects of trihexyphenidyl hydrochloride (Artane( trade mark )), an anticholinergic drug, on memory functioning. Of the 24 cognitively intact, elderly participants (age range 62-76), 12 who possessed the epsilon4 allele, participated in a double-blind, randomized, placebo-controlled, crossover, three-way study. All participants were tested after receiving a single oral dose of trihexyphenidyl (1 or 2 mg) or placebo, with a 7-day washout period between sessions. Memory and psychomotor tests were administered at baseline, and at 1, 2.5, and 5 h post-treatment. Results showed that participants with the epsilon4 allele demonstrated significant impairments in delayed recall after both 1 and 2 mg doses of trihexyphenidyl while the non-epsilon4 group did not. Additionally, while acute administration of the 2 mg dose significantly impaired total recall in both epsilon4 and non-epsilon4 carriers, the epsilon4 carriers showed a more persistent impairment. These findings held when participants with the epsilon2 allele were excluded from the analyses. The epsilon4 groups did not differ with respect to psychomotor performance or plasma drug levels. These results provide evidence suggesting that the epsilon4 allele plays a significant role in increasing cognitive sensitivity to trihexyphenidyl and that a temporal component of memory consolidation may be especially vulnerable. A larger study is warranted to confirm these preliminary findings

Increased platelet activation with release of procoagulant factors from their alpha granules has been demonstrated in individuals with major depression. Platelet activation has also been shown to be associated with release of beta-amyloid peptides, which have been implicated in Alzheimer's disease. Thus, we are hypothesizing that sustained elevations of Abeta peptides might occur in individuals with recurrent depression. We further hypothesize that such elevations contribute to brain abnormalities in depressed individuals through the formation of neurotoxic oligomeric forms of Abeta peptides and amyloid deposition. We also propose that increased amyloid Abeta peptides from platelet activation may be a mechanism underlying the increased risk for cognitive impairment in nondepressed patients who have other reasons for such activation. If true, our hypothesis would imply that platelet inhibitors may have a role in preventing or delaying the neuronal consequences of disorders characterized by activated platelets