Epidemiology Report: Analyzing Study Designs on Green Space & AD Risk

This report provides a detailed review of several epidemiological studies investigating the relationship between exposure to green spaces and the risk of Alzheimer's Disease (AD) in UK adults. It critically assesses the strengths and weaknesses of different study designs, including retrospective case-control studies, cohort studies, and cross-sectional studies. The report evaluates the methodologies used for data collection, such as interviews, GPS tracking, and questionnaires, and discusses potential sources of bias and error. Furthermore, it proposes an improved quantitative research design involving an observational study to assess the impact of wander gardens on AD risk, incorporating biomarkers, cognitive assessments, and statistical analyses to determine the association between green space exposure and AD.

Running head: EPIDEMIOLOGY
Task on epidemiology
Name of the Student
Name of the University
Author Note

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Task A
Study 1- The proposal is based on a retrospective study where the participants will
be recruited via the telephone list and charity mailing. The intent to conduct an observational
study that was based on a case-control approach. The major strength of this study design
can be accredited to the fact that this type of research helps in the determination of the rate
of association between a range of risk factors and the major outcomes (1). Owing to the fact
that the factors are responsible for affecting exposure, commonly referred to as risks of
disease, measuring the impacts of time spent in green spaces among people diagnosed with
AD and their non-diseased counterparts is a correct step. The population sampling is also
accurate since the people belonging to the case group will be recruited from GP records (2).
However, disparities between the case and the control group might lead to bias in the
results. The researchers also proposed a correct method of collecting information about the
exposure to green spaces and risk of AD.
Considering interview as the data collection method was beneficial since it is based
on a personal type of research and provides the opportunity for direct interaction (3).
However, some of the common sources of error that might arise in this research are namely,
non-response error, specification error, measurement error, and selection error. The
researchers did not mention the ways by which these errors could be averted (if any). The
researchers proposed the calculation of an odds ratio. This would be a correct approach in
determining the probability of exposure to green spaces in the control group. However, it
would not help in establishing a correlation between AD and exposure, between patients in
the case group (4). Moreover, two potential disadvantages of this research can be related to
observation bias regarding information to exposure, and no calculation of absolute risks.
Study 2- The researchers have proposed an observational study, specifically a
cohort study. The primary advantage of this research design can be attributed to the fact that
it will allow the calculation of incidence rate of AD in the exposure group, and will also
facilitate the evaluation of different impacts of the singe exposure (green spaces) (5). The

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researchers have proposed use of a GPS tracking wristwatch that will allow them to keep a
track of the time spent in green spaces, and further determine its correlation with AD onset.
Conduction of a baseline assessment is another strength since it will help in the establishing
a point from which upcoming dimensions and calculations can be premeditated (6). Although
the researchers have proposed measuring the daily movement during each follow-up period,
the exact timeline of the study was not proposed. Rate ratio refers to the relative difference
measure that is used for comparing the event incidence rates that occur at a certain point of
time. The fact that the researchers have also cited the need of conducting cognitive and
mental state assessments for diagnosing AD among the recruited individuals is a correct
step.
However, conduction of blood tests is also essential for ruling out the possibility of
other dementia causes, apart from AD. Recruitment of a large sample size will increase the
reliability of the results, thus facilitating the detection of statistically significant changes in the
research (7). Although the researchers will adopt the strategy of purposive sampling that will
allow them with necessary justification for drawing generalisation from the larger sample, the
process can be greatly prone to researcher bias. The process might also lead to difficulty in
defending sample representativeness. However, some of the weaknesses of the proposed
study can be attributed to the fact that the researchers would have to follow a large number
of participants for a long period of time. Furthermore, the study will be time consuming and
expensive. Loss to follow-up refers to the participant who although actively contributed to the
research at a certain point of time, often get lost or unreachable during follow-up period (8).
Thus, differential loss to follow-up period might also result in introduction to bias.
Study 3- This study is another observational study that is based on cross-sectional
design and will analyse the data from a certain population at a specific point of time. The
major strength of this proposed research can be accredited to the fact that it will allow the
collection of large cross-sectional data at little expense (9). Furthermore, owing to the fat that
multiple variables will be considered during data snapshot, the findings can be analysed for

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supporting or negating the hypothesis. The age group of the participants is correct since
early onset AD is a relatively rare type of dementia that affects people aged less than 65
years (10). However, apart from the age group the researchers did not mention about any
other inclusion factor. The exclusion criteria that would eliminate participants who are not
prospective of the intended research was correct. However, they could have written about
exclusion of patients who have vascular dementia or fronto-temporal dementia. Use of
questionnaires as the data collection instruments was a correct approach as they will allow
collection of responses from several participants. Although the researchers did not mention
the type of questionnaire that will be used, from their statement it can be deduced that the
participants will be made to describe their exposure to green spaces (11).
Hence, it can be suggested that unstructured questionnaires will be used for the
research. One advantage of this data collection method is that the respondents can provide
answers in any way, thus leading their interview. However, coding the answers of the
questionnaire often results in distortion of the distinct answers that are provided by the
individuals. The researchers have proposed the calculation of cumulative incidence that will
be assessed as the number of new cases of AD divided by total participants of the study.
This will prove useful since it will help in determining the probability of disease development
over a definite period of time. However, the authors did not mention about the time span that
the study will encompass. Furthermore, conduction of the cross-sectional study will not
determine the cause and effect.
Task B
A better study can be conducted in terms of a quantitative research design where an
observational study will be conducted for 2 successive years, with the study beginning a
year before the opening of wander gardens and a year of assessment after the event. An
estimated 50 people will be recruited from primary health care centres who do not report any
chronic conditions and age aged more than 55 years of age. They will be selected if they do
not have access to green spaces near their household or locality. A year of assessment,

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prior to their interaction with the green spaces would involve early detection biomarkers,
blood tests, neuroimaging, mild cognitive impairment and cerebrospinal fluid proteins.
Furthermore, the global Clinical Dementia Rating (CDR), Mini Mental state examination
(MMSE), and Functional Activities Questionnaire (FAQ) will also be used (12) (13). Following
recording of all the baseline scores, the participants will be asked to access the wander
garden. The number of day and hours that they spent in the region will be rigorously
recorded. After a year, the same assessments shall again be conducted to obtain the
scores. Vivid statistics, regression analyses, and Pearson’s correlations, will be used for
examining the association of wander garden habit to the final scores, in order to determine
AD risks. All the variables will also be subjected to bivariate Pearson correlations. The risk of
association will also be calculated by odds ratio (OR) that will help in determining whether
the exposure of the participants to green spaces increased or decreased their risk of AD.

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