37

CHAPTER – I

SURVEY OF ALZHEIMER’S DISEASE PREVALENCE IN

CHOSEN MEDICAL COLLEGE HOSPITALS OF

TAMILNADU

38

SURVEY OF ALZHEIMER’S DISEASE PREVALENCE IN

CHOSEN MEDICAL COLLEGE HOSPITALS OF

TAMILNADU

INTRODUCTION

In 1906, Dr. Alois Alzheimer, a German neuroscientist, described the

neuropathological features found in the brain of a 55 year old woman suffering

from progressive dementia. Grossly, there is cerebral atrophy in Alzheimer’s

disease, most marked in fronto temporal association cortices, not affecting the

primary motor, sensory or visual areas of the brain (Perl, 2000). Microscopic

examination typically shows neurofibrillary tangles and plaques. Neurofibrillary

tangles are dense fibrillary aggregates in the cytoplasm of neurons, composed of

hyper phosphorylated tau protiens. Senile plaques are large structures, containing

extracellular accumulation of Beta-amyloid. Granulovacuolar degeneration,

Hirano bodies and amyloid angiopathy are typical associated features in

Alzheimer’s disease (Braak and Braak, 1991).

Alzheimer’s disease develops after the age of 65 years in majority of the

cases. Rarer forms of Alzheimer’s disease occur from the fourth decade of life

until the age of 65 years. Alzheimer’s disease is the fourth leading cause of death

among adults in the United States (Barbara et al., 1998). The prevalence of

Alzheimer’s disease increases with age, being 5% at 65 years of age and doubling

every 5 years (Hendne, 1998). Several studies have shown higher prevalence in

women (Jorm and Jolley, 1998). With the increase in life expectancy and rising

39

population of the elderly, the prevalence of Alzheimer’s disease is expected to

rise in the future causing a major public health problem.

Approximately 4.5 million people in the United States are currently

afflicted with this disorder, and the number is expected to rise sharply in near

future due to the increase in the elderly population, which represents the fastest

growing segment in our society (Hebert et al., 2003). It is estimated that nearly

13−16 million people will suffer from AD by 2050 and, among those, nearly 13%

of individuals over age 65 may be affected (Hebert et al., 2003; Maier-Lorentz,

2000). Most AD cases are sporadic, with multiple risk factors, such as aging,

environmental stress, and diet, suggested to play critical pathogenic roles. The

remaining AD cases, which account for 5−10% of total AD cases, are rare, but

inherited from one generation to the next and are referred to as familial AD

(FAD).

A 2003 epidemiologic report by Wimo and collogues puts the number of

people suffering from AD at 27.7 million worldwide. Although 38% of these

people are from the developed economies and the rest are in the developing

countries. China has the highest number of AD with 5.2 million while USA got

around 5 million Alzheimer's patients. In India, the prevalence of the disease is

4.7 per 1000 person. It ranks seventh among the leading causes of death in 2004,

passing influenza and pneumonia. It is also projected that there are 4.6 million

new cases added every year worldwide and expected to double in about 20 years

time suggesting new identification and intervention strategies to tackle this

disease.

40

Given the fact that AD affects older population, the heath economy costs

of this is estimated to be around 156.2 billion US dollars in 2003 by Wimo and

colleagues. Again, this estimate of the money is spent in the developed countries

on direct cost only. Apart from this, the indirect costs along with other effects on

the health sector implicate the high impact of this disease on the economy. The

2003 estimates put the money spent on AD as follows: USA around 48.6 billion

dollars, Japan 24.7 billion dollars, EU countries together 60.5 billion dollars

(Wimo et al., 2003; 2006).

AD control measures can be well carried out only, if the incidence of the

disease has been found out. Epidemiology data on AD in India is some what

scanty. With the exception of the National Sample Survey (NSS) done in 1955-

58, virtually no other information is available at the national level. In this regard,

the present study was carried out to point out the prevalence of AD cases among

the population enrolled in the four medical colleges of Tamilnadu.

41

MATERIALS AND METHODS

Alzheimer’s disease is a complex neurodegenerative disease with

cognitive, behavioral and neurologic manifestations.

• Cognitive abnormalities include progressive disturbances in declarative

memory, semantic comprehension and naming, visuo-spatial skills and

executive abilities.

• Neuropsychiatric and behavioral disorders associated with Alzheimer’s

disease include:

� Psychosis: Hallucinations and delusions

� Mood abnormalities: Depression, euphoria, anxiety, irritability

� Alterations in personality-apathy, disinhibition

� Agitation, aggression, wandering changed sleep patterns

� Altered sexual behaviour - Disturbances of appetite

• Neurological abnormalities are typically delayed until late in the course of

the disease and include:

� Incontinence

� Quadreparesis in flexion

� Dysphagia

• The impairment is insidious in onset and gradually progressive and is so

severe as to interfere in social and occupational functioning. A broad

survey was made in four different places of Tamilnadu. The detailed

description of these cities are given below.

42

Study Area and population

Chennai

Chennai is the capital city of the State, besides being an important district.

The district city is one of the metropolitan cities of India and serves as the

gateway of the culture of South India. In spite of being the capital of a Tamil

speaking State, it has emerged as a cosmopolitan city playing an important role

in the historical, cultural and intellectual development of India.

Fig. 1. Area map of Chennai (data collection site)

Source: www.mapsofindia.com

43

Chennai is situated on the north-east end of Tamil Nadu on the coast of

Bay of Bengal. It lies between 12° 9' and 13° 9' of the Northern latitude and 80°

12' and 80° 19’ of the Southern longitude on a `sandy shelving breaker swept

beach. It stretches nearly 25.60 kms (Fig. 1). Along the Bay coast from

Thiruvanmiyur in the south to Thiruvottiyur in the north and runs inland in a

rugged semi-circular fashion. It is bounded on the east by the Bay of Bengal and

on the remaining three sides by Chengalpattu and Thiruvallur Districts.

Its population was estimated to about 42,16,268 (Survey-2001), has a

population density of 24,231 individuals per sq. Km. Male literacy is 84.71% and

female literacy is 75.32%. Madras Medical College (MMC) is situated in the

middle of the city with sophisticated facilities. It is having a separate neurology

wing with all clinical diagnosis and treatment facilities.

Salem

Salem is an important district of Tamil Nadu notable for its picturesque

landscapes dotted with hillocks, lakes, temples, forts etc. The district has its

administrative head quarter located at the same town of Salem. Other major

towns of the district include, Mettur, Omalur and Attur. It lies between 12° 53’ of

the northern latitude and 77° 44’ and 78° 50’of the eastern longitude (Fig. 2).

44

Fig. 2. Area map of Salem (data collection site)

Source: www.mapsinfobase.com

It spreads over an area of 5205 sq. km. Its population was estimated to

about 3016346 (Survey-2001), has a population density of 573 (Per sq. km.). Sex

ratio of this district is 929 females per 1000 males. It has a literacy rate of

57.50% and the average rain fall is 363.5 mm. Mohan Kumaramagalam Medical

College is situated in Salem. Most of the neuro- patients of this district and the

surrounding district like Dharmapuri, Namakkal and Erode is benefitted from this

hospital.

45

Madurai

Madurai District is situated in the South of Tamil Nadu state. It is

bounded on the North by the districts of Dindigul, Thiruchirapalli and on the East

by Sivagangai and on the West by Theni and South by Virudhunagar .It lies

between 9°30.00 and 10°30.00 of the northern latitude and 77°00.00 and

78°30.00 of the eastern longitude (Fig. 3).

Fig. 3. Area map of Madurai (data collection site)

Source: www.mapsofindia.com

It spreads over an area of 3741.73 Sq.Km. Its population was estimated to

about 25,78,201 (Survey-2001), has a population density of 689 (Per sq. km.).

Madurai district has 8 major hospitals. The Government Madurai Medical

College Hospital is having a separate Neurology wing with adequate facilities.

46

Kanyakumari

The district of Kanyakumari in Tamil Nadu, India is located at 8.08ºN

77.57ºE .It lies at the meeting point of three water bodies: the Arabian Sea, the

Bay of Bengal and the Indian Ocean. It is the terminating point of the Western

Ghats and Eastern Ghats. On the north and east it is bounded by the Tirunelveli

district, on the west and the north west is bounded by Kerala.

Fig. 4. Area map of Kanyakumari (data collection site)

Source: www.mapsofindia.com

47

It spreads over an area of 1684.4 Sq.Km. Its population was estimated to

about 16,69,763 (Survey-2006) spreading over four taluks including four

municipalities, 56 town panchayat union. The males constitute about 50% of

population and females 50%. Kanyakumari has an average literate rate of

88.11%, higher than the national average of 59.5%, Male literacy is 90.88% and

female literacy is 88.38%.

Kanyakumari has a pleasant weather and enjoys rainfall from both

monsoon like south west monsoon (July-September) and North East monsoon

(October-December). It also enjoys the winter period (January and February).

Kanyakumari district has five well-equipped government hospitals. In addition to

four taluk hospitals, there are five non-taluk hospitals and thirty health centers.

Kanyakumari District Medical College Hospital is situated in Asaripallam. It is

one of the earliest TB Hospital established in South India

Survey of Neurological patients of chosen medical college hospitals of

Tamilnadu

A sample survey was conducted out in the above medical college

hospitals of Tamil Nadu, South India with the objective of finding out the

prevalence of positive Alzheimer’s patients among those enrolled for

neurological disorder in the period of 2006 - 2007. The general proforma of

neuro – patients enrolled in the hospital was collected for the study which

includes patient’s sex, age, diabetic symptoms, cholesterol status and clinical

examination. During the course of study total number of enrolled patients,

number of new cases examined, no of positive cases, no of follow-up patients, no

48

of positive patients among follow-up patients were examined and the results were

recorded.

Detection of year wise percentage AD outbreaks

From the collected data, year wise percentages, prevalence, percentage of

associated symptoms were calculated. Similarly the percentages of occurrence in

male and female populations were examined in different hospitals. From the case

register the percentage of incident among the different age groups was also

determined.

Statistical Analysis

The collected data were statistically (Skewness and Kurtosis Section,

Descriptive Statistics, correlation analysis and significance) analyzed using SPSS

software. The results were tabulated and the preliminary data are presented in

Annexure I.

49

RESULTS

The survey was made in the chosen Tamilnadu Govt. Medical College

Hospitals during 2006 - 2007. The hospitals chosen for the AD survey and

prevalence analysis are Madras Medical College Hospital, Chennai, Mohan

Kumarmangalam Medical College Hospital, Salem, Madurai Medical College

Hospital, Madurai and Kanyakumari District Medical College Hospital of Tamil

Nadu, South India, with the objective of finding out the prevalence of positive

cognitive neurodegenerative disorder among peoples enrolled in neurological

wing.

It was found that during the year 2006, a total of 4326 outpatients were

enrolled, of which 2618 were new cases. Among the new cases, examined 774

were found to have some neurological problems. However, in the overall status,

total neuro-patients observed in the four hospitals were 1398. Among that,

Chennai contributes 30.54% followed by Salem and Madurai at a rate of 25.89%

and 24.53% of neuro patients respectively. As per the results, 2.6% of the

neuropateients suffer from A.D. in Chennai. Among that 36% of the patients

were diabetic, 36% patients had high cholesterol and 27% patients were obese.

But in Madurai, the percentage has been decreased to 2.3%. Among those, 50%

were diabetic, 31% had high cholesterol and 50% were obese. The data available

from the salem government hospital indicates that 2.5% of the total neuro-

patients suffer from AD, which is accompanied by 44% diabetic, 44% with high

cholesterol and 33% with obesity. Interestingly Kanyakumari had the least

population of AD patients, that is less than 2% were reported to be AD patients,

50

among whom 40% were diabetic, 40% had high cholesterol and 40% with

obesity. The report also clearly indicated that AD. is closely linked to diabetes,

high cholesterol and obesity. In contrast to other 3 cities, Kanyakumari had more

male AD patients.

The correlation between the physical parameters (Diabetes, High

Cholesterol, Obese and Sex with Alzheimer’s Disease Patients) are given in

Table 2. AD patient’s ratio with neuro- patients in different season at different

study area, Diabetic patients and AD patients comparison, cholesterol patients

among AD patients ratio, Obese patients and AD patients ratio, male frequency

ratio and female frequency ratio in different study locations are given in Fig 5 to

10. The colonial discriminate function of AD patients of different sampling sites

are given in Fig 11.

5

1

Ta

ble

2.C

orr

elati

on

bet

wee

n P

hy

sica

l p

ara

met

ers

(Dia

bet

es,

Hig

h C

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Ob

ese

an

d S

ex w

ith

Alz

hei

mer

’s D

isea

se P

ati

ents

)

Ra

tio

(AD

/Tota

l

Pati

ents

)

Dia

bet

ic

Ch

ole

ster

ol

Ob

ese

pati

ents

T

ota

l M

ale

R

ati

o

Tota

l F

emale

R

ati

o

Ken

dal

l's

tau_

b

Rat

io (

AD

/Tota

l

Pat

ients

)

Corr

elat

ion

Co

effi

cien

t 1

.000

.37

1

.037

-.17

3

.045

.05

5

Sig

. (2

-tai

led

) .

.06

5

.852

.378

.817

.780

N

16

1

6

16

16

16

16

Dia

bet

ic

Corr

elat

ion

Co

effi

cien

t .3

71

1.0

00

-.4

92

(*)

.072

.205

-.2

71

Sig

. (2

-tai

led

) .0

65

. .0

22

.734

.333

.20

6

N

16

1

6

16

16

16

16

Chole

ster

ol

Corr

elat

ion

Co

effi

cien

t .0

37

-.49

2(*

) 1

.000

-.36

2

-.21

0

.32

5

Sig

. (2

-tai

led

) .8

52

.02

2

. .0

85

.316

.12

5

N

16

1

6

16

16

16

16

Obes

e p

atie

nts

Corr

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ion

Co

effi

cien

t -.

17

3

.07

2

-.3

62

1.0

00

.020

-.0

30

Sig

. (2

-tai

led

) .3

78

.73

4

.085

. .9

24

.88

6

N

16

1

6

16

16

16

16

Tota

l M

ale

Rat

io

Corr

elat

ion

Co

effi

cien

t .0

45

.20

5

-.2

10

.020

1.0

00

-.90

6(*

*)

Sig

. (2

-tai

led

) .8

17

.33

3

.316

.924

. .0

00

N

16

1

6

16

16

16

16

Tota

l F

emal

e

Rat

io

Corr

elat

ion

Co

effi

cien

t .0

55

-.2

71

.325

-.03

0

-.9

06

(**)

1.0

00

Sig

. (2

-tai

led

) .7

80

.20

6

.125

.886

.000

.

N

16

1

6

16

16

16

16

5

2

Ra

tio

(AD

/Tota

l

Pati

ents

)

Dia

bet

ic

Ch

ole

ster

ol

Ob

ese

pati

ents

Tota

l M

ale

Rati

o

Tota

l F

emale

Ra

tio

Spearm

an

's r

ho

Rat

io (

AD

/Tota

l

Pat

ients

)

Corr

elat

ion

Co

effi

cien

t 1

.000

.47

8

-.0

02

-.19

6

.132

-.0

39

Sig

. (2

-tai

led

) .

.06

1

.996

.467

.627

.88

7

N

16

1

6

16

16

16

16

Dia

bet

ic

Corr

elat

ion

Co

effi

cien

t .4

78

1.0

00

-.5

51

(*)

.069

.260

-.3

14

Sig

. (2

-tai

led

) .0

61

. .0

27

.799

.330

.23

7

N

16

1

6

16

16

16

16

Chole

ster

ol

Corr

elat

ion

Co

effi

cien

t -.

00

2

-.55

1(*

) 1

.000

-.39

5

-.24

8

.35

5

Sig

. (2

-tai

led

) .9

96

.02

7

. .1

30

.354

.17

7

N

16

1

6

16

16

16

16

Obes

e p

atie

nts

Corr

elat

ion

Co

effi

cien

t -.

19

6

.06

9

-.3

95

1.0

00

.000

.00

5

Sig

. (2

-tai

led

) .4

67

.79

9

.130

. 1.0

00

.98

6

N

16

1

6

16

16

16

16

Tota

l M

ale

Rat

io

Corr

elat

ion

Co

effi

cien

t .1

32

.26

0

-.2

48

.000

1.0

00

-.94

6(*

*)

Sig

. (2

-tai

led

) .6

27

.33

0

.354

1.0

00

. .0

00

N

16

1

6

16

16

16

16

Tota

l F

emal

e

Rat

io

Corr

elat

ion

Co

effi

cien

t -.

03

9

-.3

14

.355

.005

-.9

46

(**)

1.0

00

Sig

. (2

-tai

led

) .8

87

.23

7

.177

.986

.000

.

N

16

1

6

16

16

16

16

* C

orr

ela

tion is s

ign

ific

ant

at

the

0.0

5 le

vel (

2-t

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d)

;

**

C

orr

ela

tion is s

ignific

ant

at th

e 0

.01 le

vel (

2-t

aile

d).

53

Fig. 5. AD patients / Neuropatients ratio in different durations at study areas

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Chennai Madurai Selam Unknown

Study Locations

Rati

o V

alu

e Aug-Oct 2006

Nov-Jan 2007

Feb-Apl 2007

May-Jul 2007

54

Fig. 6. Number of diabetic patients in observed AD patients

0

20

40

60

80

100

120

1 2 3 4

Study Locations

Rati

o V

alu

e Series1

Series2

Series3

Series4

55

Fig. 7. Number of high cholesterol patients in observed AD patients

0

20

40

60

80

100

120

1 2 3 4

Study Locations

Rati

o V

alu

e Series1

Series2

Series3

Series4

56

Fig. 8. Number of obese patients in observed AD patients

0

20

40

60

80

100

120

1 2 3 4

Study Locations

Rati

o V

alu

e Series1

Series2

Series3

Series4

57

Fig. 9. Male frequency ratio in total AD patients from different study locations

0

20

40

60

80

100

120

1 2 3 4

Study Locations

Rati

o V

alu

e Series1

Series2

Series3

Series4

58

Fig. 10. Female frequency ratio in total AD patients from different study

locations

0

20

40

60

80

100

120

1 2 3 4

Study Locations

Rati

o V

alu

e Series1

Series2

Series3

Series4

59

Fig. 11

60

The general proforma of outpatients enrolled in the hospital was collected

for the AD prevalence study, which includes patient’s sex, age, general symptom,

cholesterol, obesity and diabetes examination were carried out in the four major

Government hospitals of Tamilnadu. During the course of study, the total number

of enrolled outpatients, number of new cases examined, no of positive cases, no of

follow-up patients, no of positive patients among follow-up patients were

examined and the results were recorded. It was found that during the year 2006, a

total of 4326 outpatients were enrolled, of which 2618 are new cases. Among the

new cases examined, 774 were found with neurological problems. However, in the

overall status of neuro-patients observed in the four hospitals were 1398. Among

that, Chennai contributes 30.54% followed by Salem and Madurai at a rate of

25.89% and 24.53% respectively. As per the results, 2.6% of the neuropateients

suffer from A.D. in Chennai. Among that, 36% of the patients were diabetic, 36%

patients had high cholesterol and 27% patients were obese. But in Madurai, the

percentage has been decreased to 2.3%, among those 50% were diabetic, 31% had

high cholesterol and 50% were obese. The data available from the Salem

government hospital indicates that 2.5% of the total neuro-patients suffer from AD,

which is accompanied by 44% diabetic, 44% with high cholesterol and 33% with

obesity. Kanyakumari had the least population of AD patients, interestingly less

than 2% were reported to be AD patients, among whom, 40% were diabetic, 40%

had high cholesterol and 40% with obesity. The report also clearly indicated that

AD. is closely linked to diabetes, high cholesterol and obesity. In contrast to other

3 cities, Kanyakumari had more male AD patients.

61

DISCUSSION

Neurological diseases are common disorders, resulting in various degrees

of disability and loss of productive life. A change in demographic profile towards

the aging population was observed recently in India. Reports also have shown an

increasing trend of stroke and dementia in India (Banerjee et al., 2005). The area

based prevalence studies from India have documented a crude prevalence rate of

dementia ranging from 8.4 to 35 per 1000 among population above the age of 55 yr

(Saha et al., 2003; Vas et al., 2003; Gourie-Devi et al., 2004; Shaji et al., 2005).

Age specific prevalence of dementia also revealed higher rate with advancement of

age (Banerjee et al., 2005; Vas et al., 2003; Gourie-Devi,et al., 2004; Shaji,et al.,

2005). Though there are many prevalence studies on neurological diseases, there

are inherent weaknesses in terms of methodology of case ascertainment, case

definition, sampling of study population and lack of age variation rate in national

and international population. This might be the primary reasons for wide variations

of prevalence rate among neurological disorders in India. To overcome these

problems, random selection of sample population is required, which will ensure the

chance of equal representation of different groups in the study population and

inclusion of both health seeking and non health seeking subjects. So that, the

present study selected four different sampling areas like highly populated, metro

city (Chennai), medium populated, industrialized (Salem), thick populated and

rural based (Madurai) and highly educated and hygienic populations

(Kanyakumari). Apart from these, the chosen area has some geographical, climate,

food and life style variations.

62

The Alzheimer's Association today reports that, in 2007, more than 5

million people in the United States were living with Alzheimer's disease. This

number includes 4.9 million people over the age of 65 and the rest were below the

age of 65 with early onset Alzheimer's disease and other dementias. There was

10% increase from the previous prevalence of nationwide estimate. The greatest

risk factor for Alzheimer's is, increasing age, and with 78 million baby boomers

beginning to turn 60 last year. It is estimated that someone in America develops

Alzheimer's every 72 seconds; by mid-century someone will develop Alzheimer's

every 33 seconds.

Alzheimer’s disease develops after the age of 65 years in majority of the

cases. Rarer forms of Alzheimer’s disease occur from the fourth decade of life

until the age of 65 years. AD is the fourth leading cause of death among adults in

the United States (Barbara et al., 1998). The prevalence of Alzheimer’s disease

increases with age, being 5% at 65 years of age and doubling every 5 years

(Hendne, 1998). Several studies have shown higher prevalence in women (Jorm

and Jolley, 1998). With the increase in life expectancy and rising population of the

elderly, the prevalence of Alzheimer’s disease is expected to rise in the future

causing a major public health problem.

Approximately 4.5 million people in the United States are currently

afflicted with this disorder, and the number is expected to rise sharply in future

years due to the increase in the elderly population, which represents the fastest

growing segment in our society (Hebert et al., 2003). It is estimated that nearly

13−16 million people will suffer from AD by 2050 and, among those, nearly 13%

63

of individuals over age 65 may be affected (Hebert et al., 2003; Maier-Lorentz,

2000).

The results of the present study indicated that 2.6% of the neuropatients

suffer from A.D. in Chennai. Among that 36% of the patients were diabetic, 36%

patients had high cholesterol and 27% patients were obese. But in Madurai, the

percentage has been decreased to 2.3%. Among those, 50% were diabetic, 31%

had high cholesterol and 50% were obese. The data available from the Salem

Government Hospital indicates that, 2.5% of the total neuro-patients suffer from

AD, which is accompanied by 44% diabetic, 44% with high cholesterol and 33%

with obesity. Interestingly Kanyakumari had the least population of AD patients

and less than 2% were reported to be AD patients, among whom 40% were

diabetic, 40% had high cholesterol and 40% with obesity. The report also clearly

indicated that AD is closely linked to diabetes, high cholesterol and obesity. In

contrast to other 3 cities, Kanyakumari had more male AD patients.

These observations of prevalence of dementia were lower than that of

western countries. This may partly be due to strict inclusion criteria or the rate may

be truly low. As compared to higher prevalence of dementia in developed countries

ranging between 5-10% after 60 to 65 yr of age (Jackson et al., 2009), several

urban and rural studies on dementia from different parts of India had documented

lower rates varying from 1.02 to 3.36% above 60 to 65 yr of age (Shaji et al.,

2003). It is also evident that prevalence was higher in rural as compared to urban

population and is higher in southern when compared to northern states of India.

This variation of prevalence rates in different studies may partly be due to true

64

regional and rural/urban differences owing to variation in genetic factor,

environmental factors including dietary habit, age structure and literacy rate of the

study population. A study from USA has shown the protective effect of dietary

constituent (turmeric- haldi) in Indian diet against degenerative dementia (Lim et

al., 2001). Hence, multicentre studies with comparable methodologies and uniform

diagnostic criteria are needed to determine the true nature and extent of regional

and rural/urban variation in India.

In conclusion, findings of our study showed a high prevalence of dementia

compared to western figures. The heterogenecity of the population might result in

differences in prevalence rates of neurological diseases from different parts of the

country. Therefore, more epidemiological studies need to be conducted in India to

look into the changing pattern of neurological diseases using a uniform

methodology, case definition and appropriate representative sampling of study

population. Apart from finding disease prevalence, the incidence and the risk

factors should also be determined to delineate the natural course of the

neurological diseases, and to identify consequent disabilities, their socio-economic

impact on quality of life, so that appropriate remedial measures could be taken.