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organic disorders in psychology

Organic disorders

Researchers have studied incidence and prevalencerates for dementia in different areas of the world,including North America, Europe, Scandinavia,Russia, Japan, China, Singapore and Australasia. Most studies indicate higher prevalence ratesof Alzheimer's disease (AD) in comparison to vasculardementia in North America and Europe. On the otherhand, Russia, China and Japan reveal the oppositepattern. Researchers in the United Stateshave cited elevated levels of hypertension and othercardiovascular risk factors to explain evidence thatAfrican Americans, and possibly Asian Americans,show higher prevalence rates of multi-infarct dementia.

Little information exists on the age-relateddementias in the developing world, except for China,where researchers have devoted substantial recenteffort to their study. In an epidemiological survey ofcommunity residents in an urban area of Beijing usinga Chinese version of the Mini-Mental State Exam(MMSE), Li et al. observed prevalence rates ofmoderate and severe dementia of 1.28% and 1.82%for those aged 60 and above and 65 and above,respectively. These rates are considerably lower thanthose from developed countries. Given that dementiarates increase steadily with age, the authors state thatthis difference can be partly explained by the relativeage distributions of the elderly populations, with morevery old persons found in the developed countries.Zhang et al., also using a Chinese version of the MMSE, found a 4.6% prevalence rate of dementiaamong those over age 65 in a probability sample of5055 non-institutionalized elderly in Shanghai. Ofthose demented, the researchers classified 64.7% ashaving AD and 26.8% as having a vascular dementia(including multi-infarct dementia), which counters the usual observation from China of higher rates ofvascular dementias than AD.

The researchers in the Shanghai study also notedthat the prevalence rate of AD was low in comparisonto a study in East Boston  using similar methods(10.3% prevalence rate for those over 65). Katzman, proposed that the higher prevalence of ADdetected in the East Boston study could have been dueto methodological differences, specifically, the acceptanceof subjects in East Boston as cases if theypossessed clinically apparent cognitive changes withoutthe stricter DSM-III requirement of formalevidence of functional impairment used in Shanghai.Zhang et al. suggested that there may exist eitherdifferent incidence rates for dementia or differentmortality rates for those with dementia in the twocommunities, and that there is significant underrecognitionof dementia symptoms by Chinese families. Ikels argues that delayed recognition of symptomsoccurs in China, in comparison to the United States, formany reasons, including the fact that most Chineseelderly live with their families and little is expected ofthem, as younger members of the family assumeresponsibility for household affairs. Thus, the familymay easily overlook early signs of intellectualdeterioration because decline in instrumental activitiesof daily living, one of the early markers of cognitiveloss, is not readily observed. Also, lack ofrecognition of symptoms allows the family to avoid thestigma associated with mental illness in Chinese society.

In a recent review regarding the differential diagnosisand prevalence of dementing illnesses in India, Wadia argues, based on the scant published literaturefrom India and clinical experience, that there is noreason to believe that the prevalence and types ofdementing illnesses are significantly different in Indiathan in the West. Wadia cites twostudies  from South India where dementia ratesamong persons over 60 were 6.1 and 10%, respectively.Neki  presents information from an earlysample survey, showing that of the elderly hospitalizedfor mental illness in India, approximately one-eighth(12%) suffered from organic brain syndromes(including senile psychoses), compared to over a thirdfrom chronic schizophrenia and over a quarter fromdepressive illness. He posits that the rarity of senilepsychoses could be due to: (1) lower longevity; and/or(2) higher tolerance by the community for thedemented aged in India as compared to industrializedcountries. The implication of the latter explanationis that symptoms of dementia are an expected or at leastunderstandable part of aging in some subcultures of thecountry.

As early as 1966, Lambo  offered both of theseexplanations to account for the apparent scarcity ofpsychiatric disorders, including senile dementia, in theaged of the developing world, and Africa in particular.Since then, as life expectancy has improved, authorshave relied increasingly on the explanation that thein the developing world 985family harbors the mentally and physically impairedaged from the public gaze in order to preserve theirdignity and the respect that African culture confers tothem, resulting in few elderly with symptoms ofdementia being identified either in medical clinics orthrough door-to-door screening. Makanjuola supports this view in his interpretation of why so fewelderly Nigerians attend psychiatric clinics forconditions including dementia. He proposes thatfamilies are relatively tolerant of all but the mostextreme mental disturbances in the elderly and thusdelay or fail to seek care from medical facilities.Furthermore, in a community survey of 18,954 subjects(6% and 4%, respectively, above the age of 60 and 65)in a Nigerian village, Osuntokun et al. discoveredno cases of dementia and offered as a possibleexplanation of this finding the idea that families wouldnot readily provide access of door-to-door interviewersto their disabled elders.

Despite the conventional idea that the familyprotects demented elders, Osuntokun et al. postulate that lower rates of age-associated dementias,particularly AD, may actually exist in Africa due to theabsence of certain as yet unidentified 'risk factors'  for discussion) found in industrializedcountries, and they summarize their own studies andobservations over the last decade to support theirassertion. In a door-to-door communitystudy using a modified MMSE to suit the local culture,they confirmed no diagnosis of dementia using ICD- 10and DSM-III-R criteria in their sample of 326individuals aged 65 and older. Furthermore, in anautopsy survey of 198 brains of Nigerians aged 40 yearsand older (45 of whom were 65 and older), they foundno psychological changes consistent with AD. Between1984 and 1989 at the University College HospitalIbadan, they diagnosed 18 of 37 dementia patients (28males and 9 females) with multi-infarct dementia butnone with AD. Also, in a consecutive series of 2182 newpatients (6% of whom were older than 65) in a Nigerianneuropsychiatric hospital, they saw no patient withAD.

One study from Nigeria does point to a higher rateof Alzheimer's type dementia. This study ofpsychiatric disorders among 73 consecutive patientsaged 60 years and older admitted for the first time intoa psychiatric hospital reported that Alzheimer's typedementia was more common among females whilemulti-infarct dementia was more common amongmales. However, the authors did not provide thespecific rates of these dementias. Senile dementia wasthe most common of the organic psychoses, whichaccounted for 30% (n = 22) of the total presentingsample.

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