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|Year : 2016 | Volume
| Issue : 4 | Page : 661-662
Leprosy and cognition
Vinay Goyal1, Binod K Khaitan2
1 Department of Neurology, All India Institute of Medical Sciences, New Delhi, India
2 Department of Dermatology, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||5-Jul-2016|
Department of Neurology, All India Institute of Medical Sciences, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Goyal V, Khaitan BK. Leprosy and cognition. Neurol India 2016;64:661-2
Leprosy (Hanson's disease), has been described in ancient Ayurvedic scripts by Charak, Susruta, etc. The first modern description of leprosy was published by Norwegian researchers in 1847. Armauer Hansen (1895) discovered the bacillus of leprosy. As per the WHO report (2013), Southeast Asia still has the highest incidence (71% of worldwide cases, 59% cases in India alone) of new cases of leprosy. Conventionally, leprosy involves skin and nerves (and has a predilection for colder tissue at 27-30 degree). The other organs affected by leprosy are the nose/larynx, oral cavity, lymph nodes, spleen, liver, testes, eyes, kidneys, bones and joints and adrenal glands.
When Mycobacterium leprae ffect brain directly, discussing the relationship between cognition and leprosy sounds interesting. Of course, the cognitive aspect may be affected due to the situation, disability and sequel created by the disease or by the drugs used for treatment. Associated physical disability and social isolation may contribute to the cognitive decline.
There has been an interesting observation regarding beta-amyloid and tau deposits in the brain of patients with leprosy. Beta-amyloid deposits were lower in the brain of patients with leprosy (27%) as compared to controls (47.8%, P = 0.05); and, similarly senile plaques (classic type III) were also less in the patients suffering from leprosy. It is not clear if this is due to the effect of leprosy or of anti-leprosy drugs. As the lepra bacillus does not reach the brain, the possibility of the effect of medication on cognition needs evaluation.
In this issue, the article on the cognitive aspect of leprosy by Kang KW et al., is interesting to read. Kang and his colleagues evaluated the cognitive function of 224 persons with leprosy (with 448 age/gender matched controls) using the Korean version of mini-mental state examination (K-MMSE), the Korean Dementia Screening Questionnaire (KDSQ) and the Seoul-Instrumental ADL (S-IADL) for assessment of their cognitive abilities and their ability to carry out activity of daily living (ADL). K-MMSE score was higher in patients with leprosy as compared to the control population (P = 0.022, P < 0.001 when adjustments for age, gender, and educational year were done) but KDSQ did not show any difference in cognition between the groups. Better K-MMSE score suggests a lower rate of dementia in patients with leprosy.
Previous studies have shown various results in favour of or against the cognitive decline. Rate of dementia in Japanease lepratorium was higher as compared to the national rate. The Taiwanese study by Su TW et al., also showed a higher prevalence of dementia in patients with leprosy. There is a controversial effect of dapsone on the development of dementia in patients with leprosy.,
In India, majority of neurological studies have concentrated on various neuropathies. Kochar et al., have studied the brain stem auditory evoked response and visual evoked potentials in patients with leprosy suggesting the involvement of trigeminal and optic nerves. There is no study regarding any cognitive aspect of leprosy, athough India has the largest number of patients with leprosy in the world. A recent article by Kumar discusses the challenges in the management of leprosy in India.
To resolve this issue of dementia in patients with leprosy, there is a need for a prospective case control study of patients with leprosy as India has a large reservoir of patients for research of this kind. Thus, it is feasible for researchers to generate significant epidemiological data that may have long term consequences on eradication of this dreaded disease. Also, in view of lack of evidence in favor of or against the use of dapsone to prevent/treat dementia, this medication deserves a fair chance for re-evaluation in the subcontinent.
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