RECENT PRESENTATIONS

McEvoy, L.K., Nichols, E.A., Page, B., Smith, M.E., Gevins, A. (2002). Working and Recognition Memory in Older Subjects: Effects of an Antihistamine. Cognitive Neuroscience Society Ninth Annual Meeting. April, San Francisco.

ABSTRACT

Brain cholinergic function is thought to diminish with age, negatively impacting arousal and cognition. Since the histamine system exerts a modulatory effect on acetylcholine release, antihistamines may impair cognitive function in the elderly. Diphenhydramine (DPH) is a commonly used histamine H1 receptor antagonist that, in animals, induces memory deficits that are reversible by acetylcholine agonists. To examine the effect of DPH on recent episodic and working memory (WM) in healthy older subjects, a double-blind, counterbalanced study was performed in which EEGs were obtained from 12 adults (62 -75 yrs; average IQ 125). Recent episodic memory over a 5-10 min. period was measured with a word recognition task. WM was assessed with easy and difficult levels of a spatial n-back task. DPH produced significant subjective drowsiness and a trend towards slower task performance. In the WM task, DPH increased EEG power in the 2-10Hz range, suggestive of decreased arousal. DPH increased the latency and decreased the amplitude of the attention-related P300 component of the event-related potential (ERP). In the ERPs recorded during the verbal recognition task, DPH attenuated the positivity observed to correctly recognized old words (relative to new distractor words) in the interval of 300-600msec after word onset. The results indicate that minor alterations to normal histaminergic/cholinergic neurotransmission can significantly impact neurophysiological correlates of attention and memory in the elderly. Supported by NIA & NINDS.