Five Hundred Patients with Memory Loss in One Clinic in India: Does the Prevalence Vary Between Communities?

Educational level

We had not recorded the education level in the first 100 patients. Previously many researchers had reported that lower education was a risk factors for dementia [15, 16], but later studies have refuted this finding [17] proposing that there may be a more consistent relationship when years of education reflected cognitive capacity.

We decided to enquire about the educational level of the patient from the next of kin. The findings are revealing.

Why don’t clinicians report dementia with Lewy bodies?

The cardinal features of DLB as described in the review article of the DLB consortium [9] are:

In patients of DLB seen in our clinic, the dementia is usually mild permitting the patient to continue with some routine activities. Fluctuation is often prominent leading to family members believing that the patient is “pretending to be ill” and can be normal when he/she desires. Hallucinations, specifically visual hallucinations, are rarely reported by family members as there is no appropriate word in the local language for hallucinations. Frequently relatives report “dreams while awake” or talking to their long dead relatives. Some relatives report that the patient believes his/her spouse of 50 years is a thief. A few report that the patient imagines there are snakes or ants on the wall. These patients may be taken to psychiatrists who prescribe potent anti-psychotics in increasing doses until side-effects appear. REM sleep disturbance are hard for relatives to report. Finally, features of parkinsonism are diagnosed as Parkinson’s disease, which is easier to diagnose and treat with syndopa.

Few busy clinicians will try to put all signs and symptoms into one diagnosis of DLB. There is now increasing awareness of “dementia” among General Physicians but rarely is there effort to try to determine the cause or type of dementia. Thus, the diagnosis of DLB is usually not established.

Summary of discussion from the previous publication

Most of the discussion of the results are as in our previous publication [6], and only the salient features will be repeated here.

As reported in our finding of 100 patients, while AD is reported to be the most common cause of degenerative dementia globally [18], in this series, DLB exceeds AD. Globally DLB is the second most common variety of degenerative dementia after AD [9].

In this series, VaD due to large vessel or small vessel disease is not as common as expected, given the increasing incidence of stroke in India. The four common risk factors for cerebrovascular disease (diabetes, hypertension, tobacco use, and dyslipidemia) are rampant and increasing in South-East Asia [19]. Yet not many cases of cardiovascular disease report to hospitals; perhaps mortality is high outside the hospital.

Depression is a common cause of memory loss in this series. This may be due to older people living alone and away from their children who are often abroad. This has had a severe impact on the traditional caring system where the joint family featured prominently. It is also reported to be an under-diagnosed condition with patients presenting with other psychosomatic symptoms such as “forgetting”. It is also an under-treated condition with most patients (as in this series) refusing treatment or being referred to a psychiatrist.

MCI causes cognitive changes that are serious enough to be noticed by the individuals experiencing them and or by their family members. Yet these changes are not severe enough to interfere with routine life or independent functioning.

SCD is receiving increasing attention as a risk factor for future AD [14]. The categorization of SCD is largely based on self-reported symptoms by the individual and the interpretation by the clinician. Since there are no specific neuropsychological tests or scores for its diagnosis, the conclusion is often subjective on the part of the clinician.

It should be noted that the differential diagnosis of the types of dementia done here was clinical. They were not based on laboratory and nuclear medicine tests as these are unaffordable to most in a less resourced country where medical expenses are paid out of pocket. Consequently, no sophisticated tests, such as amyloid imaging (not available in India as yet) or fMRI were done.

This study is the first, largest, and only case series examining the distribution of cause of memory loss seen in a Dementia clinic.

Other studies [20] generally deal with population-based studies of the prevalence of all dementias, with small number of subjects. They are conducted for awareness generation and planning. The objective of this study (to study the subtypes of memory loss) is different from the population-based studies of the prevalence of dementia. Moreover, there are no clinical series of patients describing the relative proportion of types of dementia.

There is limited information on risk factors for dementias in the cases studied. Cost is a major consideration among families of patients, many of whom have given up their jobs or are paying substantial sums of money for caregivers. Therefore, our established way of practice in the Dementia clinic is to recommend those tests which help us make a diagnosis (MRI brain). Other tests such as blood sugar and vitamin levels are available in most patients but not for the entire sample, thus meaningful analysis is not possible.

As mentioned before, the best-known risk/protective factor, educational level, cannot be assessed in a structured manner, particularly in older patients who have been farmers or housewives. Thus, asking a patient the number of grades of education would not apply. Tests of research interest (APOE4) were not recommended.

The distribution of dementia types in this much larger series than the first report is surprising. Why DLB cases should outnumber cases of AD remains unknown. One possible explanation could be the variation in genetic makeup of the Indian population which are widely known. For example, N-acetyltransferase 2 gene polymorphism as a predisposing factor for phenytoin toxicity in the Indian population [21], HLA-B 1502 allele and its role in carbamazepine toxicity in Indians and other Asian communities [22], and more recently the association of HLA with oxcarbazepine-induced toxicity in Asians [23] are well documented. The role of APOE4 in AD is also established and its distribution is similar between the Indian and US populations. However, the prevalence of dementia is lower in India compared to the US [24]. Not much is known yet about the genetic abnormalities in DLB. Perhaps when the genetic markers in DLB are identified and extensively available in genetic laboratories, this could shed light on this difference.

Conclusion

This is the only study to report on the relative frequency of cause of memory loss in a clinical series. The observation that DLB outnumbers AD should be verified by other researchers. Perhaps genetic researchers would like to investigate the genetic makeup of patients clinically diagnosed with DLB. Clinicians should be aware that “dementia” is not the “end” of the diagnostic workup and determining the cause of dementia is important. As clinicians have a saying, “The ABC of Parkinson’s disease, it’s not just about shaking” [25], it can also be said that “Everyone who forgets, does not have Alzheimer’s disease.”