The pharmacological management of cognitive impairment in the demented patient

Drug treatment of Alzheimer's disease. Effects on caregiver burden and patient quality of life

Alzheimer's disease is a devastating illness that will become more common as the population ages. Although clinical diagnosis of the illness is not certain without histological examination of the brain, and misdiagnosis may occur, broad working criteria to help diagnose the likely presence of Alzheimer's disease are available. Thoughtful clinical evaluation improves diagnostic accuracy, and appropriately diagnosed patients are critical for involvement in research into new antidementia agents. Essential to the discovery of new drugs is careful measurement of illness response. A variety of scales--some aimed at patients, others at their caregivers, and yet others for clinicians--assess Alzheimer's disease severity, progression, symptom response, and quality of life. Of note, patient response is not the only measurement of treatment benefit today. Growing interest is also being placed on tracking the possible amelioration of caregiver 'burden'. This burden refers to the psychological, physical, and material costs of providing care for an Alzheimer's patient over long periods of time. A number of scales and questionnaires have been developed and are occasionally used. Many drugs have been tried in Alzheimer's disease, but very few have produced any benefit, and this is often modest. Ergoloid mesylates, initially thought to be effective, are now considered of little value. The cholinomimetic drugs, especially the acetylcholinesterase inhibitor tacrine, have provided a very modest benefit, slowing the progression of the illness for a number of months. No cognitive improvement has been noted with the various nootropic agents such as piracetam. Early studies with levacecarnine (acetyl-L-carnitine), a substance that facilitates the use of fatty acids, memantidine, the dimethyl derivative of amantidine, and the calcium channel blocker nimodipine, have shown some promise, but require larger, more rigorous studies. As mentioned above, documenting effects in individual patients is crucial; examining for potential benefit to caregivers is a growing part of research design. Current treatment efforts will become more sophisticated as a deeper understanding of the neurobiology of Alzheimer's disease develops. For the immediate future, the goal is not cure but slowing of the disease process. Achieving this limited goal would have a substantial impact on the financial and human costs of the illness.

Serotonergic modulation of cholinergic function in the central nervous system: cognitive implications

Accumulating evidence suggests that serotonin may modulate cholinergic function in several regions of the mammalian brain and that these serotonergic/cholinergic interactions influence cognition. The first part of this review is an overview of histological, electrophysiological and pharmacological (in vitro, in vivo) data indicating that, in several brain regions (e.g., hippocampus, cortex and striatum), there are neuroanatomical substrates for a serotonergic/cholinergic interaction, and that alterations in serotonergic activity may induce functional changes in cholinergic neurons. In the second part, the review focuses on experimental approaches showing or suggesting that central cholinergic and serotonergic mechanisms are cooperating in the regulation of cognitive functions. These arguments are based on lesion, intracerebral grafting and pharmacological techniques. It is concluded that not all mnesic perturbations induced by concurrent manipulations of the serotonergic and cholinergic systems can be attributed to a serotonergic modification of the cholinergic system. The cognitive faculties of an organism arise from interactions among several neurotransmitter systems within brain structures such as, for instance, the hippocampus or the cortex, but also from influences on memory of other general functions that may involve cerebral substrates different from those classically related to mnesic functions (e.g., attention, arousal, sensory accuracy, etc.).