Akademik

   In biomedicine the notion of old age tends to refer to the age group of 65 years and older. Within the group of non-institutionalized individuals thus defined, the mean incidence and prevalence of hallucinations are somewhat higher than in the younger age groups, especially for those experienced in the visual modality. This increase in incidence and prevalence is attributed not only to the increased prevalence of diseases in old age but also to CNS changes characteristic of ageing. Based on cross-sectional surveys of clinical populations, prevalence figures for hallucinations among the elderly lie between 15 and 30%. These hallucinations can occur in any of the sensory modalities. Again a significant proportion of them is * visual in nature, as opposed to the predominantly * auditory nature of the hallucinations found among adolescents and young adults. Visual hallucinations and *illusions in the elderly would seem to occur especially at dusk or at other occasions where light is relatively scarce (i.e. in association with vesperal confusion). Reportedly, these hallucinations and illusions often involve human figures moving about in rows, in a straight line from one side of the visual field to the other. The affective tone of the hallucinated figures is frequently described as either impassive, menacing, or sexually laden. The affected individual often recognizes one or more deceased loved ones among the hallucinated individuals, and he or she may feel surrounded by a community of deceased acquaintances. Animals such as rats, cats, dogs, and insects can feature in these hallucinations as well (i.e. *zoopsia), and some hallucinating individuals complain that the place where they are staying is overgrown with irregular branching forms in the shape of trees, branches, logs, or pine needles (i.e. *dendropsia). * Visual illusions experienced by the elderly can take the general form of a *cognitive illusion such as a shadow being mistaken for a cat or a moving curtain for a person approaching (sometimes referred to as *pareidolia). More specific illusions associated with old age are the * TV sign (i.e. the mistaken impression that a person appearing on the television screen is actually present in one's home or that events presented on television are taking place inside one's home), the *magazine sign (a similar phenomenon occurring in relation to photographs in a magazine), and the * picture sign (a similar phenomenon occurring in relation to portraits). Some organic conditions held responsible for the raised prevalence of hallucinations among the elderly are * sensory handicaps, * tinnitus, Pick's disease, Lewy body dementia, Alzheimer's disease, other types of dementia, Parkinson's disease, localized cerebral lesions, metabolic disorders, * delirium, alcoholism, and intoxication due to the use of therapeutics. Some specific types of hallucination which occur frequently among the elderly are visual hallucinations in the context of * Charles Bonnet syndrome, the * phantom boarder syndrome, *bereavement hallucinations, * sexual hallucinations, and * musical hallucinations. Moreover, studies among the dying suggest that some 50% of these experience *death-bed apparitions.

   References

   Berrios, G.E., Brook, P. (1984). Visual hallucinations and sensory delusions in the elderly. British Journal of Psychiatry, 144, 662-664.

   Berrios, G.E. (1992). Psychotic symptoms in the elderly: Concepts and models.In: Delusions and hallucinationsin oldage. Edited by Katona, C., Levy, R. London: Gaskell.

   Wertheimer, J. (1992). Some hypotheses about the genesis ofvisual hallucinations in dementias. In: Delusions and hallucinations in old age.Edited by Katona, C., Levy, R. London: Gaskell.