El planeamiento como instrumento generador del derecho a edificar

Mild cognitive impairment (MCI) is an at-risk state for developing dementia [12-15]. Often depicted as a stage within the cognitive impairment continuum [16],

4 | P a g e it has been described as a “transition phases between healthy aging and

dementia” ([15], p19). Over half of the population identified with MCI will develop dementia [17]. Progression rate into dementia is approximately 15%

per annum, although there is discussion regarding prevalence rates between the different types of MCI [15].

MCI is a condition that is characterised by a reduction in cognition without an associated loss of ability in complex functional tasks [18]. The exact prevalence of MCI is difficult to ascertain, with studies reporting between 3% and 19% in adults over 65 years [19]. Cause of MCI is attributed to a number of factors that include “cholinergic dysfunction, white-matter lesions and cerebral infarctions, extracellular amyloid deposition, and intracellular neurofibrillary tangle formation” ([12], p1264).

Diagnosis of MCI is considered when memory loss beyond what is expected of normal ageing is experienced. There is considerable heterogeneity within MCI, with four recognised sub-groups: amnesic, non-amnesic, single, and multiple domain [20]. Accurate diagnosis of MCI type will aid the inclusion of this population within research studies [20], improve the specificity and efficacy of interventions [21], and increase the accuracy of prediction of potential

progression to dementia diagnosis [14]. For this thesis, the concept that correct and early diagnosis can steer the provision of correct interventions is key [15].

By intervening at this stage in the condition, the progression to dementia may be slowed. Petersen and colleagues provide a brief explanation [16].

“Patients so identified may be an ideal population for intervention because they are reasonably healthy, and therapeutic retardation of their clinical progression would have

a significant impact both on individuals and on society in general. These patients do not have sufficiently severe

5 | P a g e pathology to render therapeutic modalities ineffective.” ([16],

p68)

Indeed, the diagnostic criteria make it clear that whilst memory has been affected, there is limited functional impairment within this population.

Implementing an intervention is therefore feasible. This point within the cognitive impairment continuum is potentially a critical opportunity to make a difference to these individuals and their futures.

At present, there are no robust treatments to reduce the risk of progressing from MCI into Alzheimer’s disease and other dementias. Current interventions can be split into pharmacological and non-pharmacological. Pharmacological interventions have investigated the use of drugs to reduce symptoms such as memantine, donepezil, rivastigmine, and galantamine [22]. At present, there are no pharmacological interventions that can stop dementia.

In general, pharmacological interventions have limited effects [23]. This may be due to a number of factors, outlined by Petersen [21] in response to poor results from a rivastigmine trial in MCI [24], including: trialling medications in stage or condition they have not been developed for; tools for diagnosis of MCI and AD not developed in the country of recruitment; inaccurate screening and diagnosis of recruited participants; and poor design resulting in potentially sub-therapeutic doses. With methodological issues limiting the results of such trials, issues regarding accurate diagnosis are relevant. Management of risk factors currently has the most convincing evidence, such as controlling systolic hypertension [12, 15].

Non-pharmacological interventions have shown more encouraging results.

Introducing compensatory or behavioural strategies using cognitive rehabilitation to maintain cognitive function has also shown promising results [25]. However,

6 | P a g e exercise has demonstrated the most significant impact on cognitive function in large cohort studies [26, 27] and meta-analysis of trials [28, 29], although there is uncertainty due to limited number of high-quality trials [30].

Completing at least 150 minutes of physical activity per week has also shown to improve cognitive function (cognitive section of the Alzheimer disease

Assessment Scale) in older adults with MCI [31]. Lautenschlager et al [31]

demonstrated a significantly different mean difference (MD) (p=0.02, MD;

exercise=-0.87, control=1.29) when comparing physical activity to a control education group at 6 months. A small sample study (n=33) also demonstrated improvements in executive function (digit-symbol [F1,26=4.18; p=0.05] and verbal fluency [F1,25=4.87; p=0.04]) following an aerobic intervention [32].

Despite gender differences in effects from the intervention, Baker et al [32] did surmise that exercise is a promising non-pharmacological intervention.

These studies focused on interventions aiming to influence cognitive function in MCI. However, dementia and cognitive impairment (CI) also influence an individual’s functional and physical ability. These characteristics need to be outlined.

The rationale for focusing on mild levels of cognitive impairment has been outlined in this chapter. Before proceeding the terminology used to refer to this population needs to be defined. The term MCI refers to a specific diagnosis rather than a description of the level of impairment. The following literature summaries and research studies are not limited according to MCI diagnosis or categorised MCI sub-types. Dementia is also a diagnosed condition. However, it is frequently used as an umbrella term for those individuals with identifiable cognitive impairment inclusive of the different dementia sub-types (such as AD or VD). The term mild dementia has therefore been adopted as a description of persons with a cognitive impairment, at a mild level, who may or may not have

7 | P a g e a specific diagnosis of MCI or dementia sub-type, but who have all been

identified from a cognitive screen or assessment. Mild dementia will

subsequently be used to describe intended participants in the following chapters.