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dementia

Dementia

Definition

Loss of intellectual abilities previously attained (memory, judgment, abstract thought, and other higher cortical functions) severe enough to interfere with social and/or occupational functioning 1).

Memory deficit is the cardinal feature, however, the DSM-IV definition requires impairment in at least one other domain (language, perception, visuospatial function, calculation, judgment, abstraction, problem-solving skills) 2).

Epidemiology

Although the preponderant prevalence in women has been identified, the sex differences in risk factors are unclear.


Disorders of memory and cognitive function are increasing in incidence as several societies deal with the demographic reality of an aging population. At present, it is estimated that 25 million people worldwide are suffering from dementia caused by Alzheimer disease (AD), with a predicted doubling in incidence every 20 years 3).

By 2040, the incidence of Parkinson’s disease (PD)—in which dementia arises in 75 % of patients at 10 years and up to 87 % at 20 years 4) will also have doubled 5).

Dementia continues to enjoy a high public and political profile, the latter exemplified by the recent G8 summit meeting declaration to develop a cure or treatment by 2025. This is only likely to be achieved by a deeper understanding of the clinical and pathophysiological phenomena of dementia disorders 6).

Even though dementia is a cardinal symptom of normal pressure hydrocephalus (NPH), there is few data available concerning cognitive functioning.


The association between exposure to general anesthesia and dementia risk has been inconsistently reported across epidemiological studies. To better understand the association, Jiang et al. conducted a metaanalysis of epidemiological studies. PubMed and Embase were searched through April 2017. Random-effects models were used to pool association estimates. They further evaluated potential dose-response relationship. Based on literature search, seven prospective/cohort studies, 11 case-control studies, and a pooled analysis of six case-control studies were identified. Sixteen of these studies were with high quality. After pooling available risk estimates, overall no significant association between exposure to general anesthesia (yes versus no) and dementia risk was detected (odds ratio (OR) = 1.03, 95% confidence interval (CI) 0.90-1.19, p for heterogeneity < 0.001). The null association persisted in the majority of subgroup analyses, although a significant positive association was detected in studies collecting anesthesia exposure using records (OR = 1.22, 95% CI 1.01-1.47, p for heterogeneity < 0.001), a method that is less prone to bias compared with interview or questionnaire using proxy reporters. Based on the dose-response analysis of three studies, a significant nonlinear relationship between times of exposure to general anesthesia and increased risk of dementia was suggested (p < 0.0001). Overall, this meta-analysis suggests that overall the evidence from epidemiological studies supporting a link between general anesthesia exposure and an increased dementia risk is not very strong, while an association was suggested in the studies collecting anesthesia exposure using records and those providing anesthesia exposure frequency data. Further well-designed studies are warranted to better characterize the relationship of interest 7).

Classification

Diagnosis

Delirium vs.dementia (critical distinction). Delirium AKA acute confusional state. Distinct from dementia, however, patients with dementia are at increased risk of developing delirium 8) 9).

A primary disorder of attention that subsequently affects all other aspects of cognition 10). Often represents life-threatening illness, e.g. hypoxia, sepsis, uremic encephalopathy, electrolyte abnormality, drug intoxication, MI. 50% of patients die within 2 yrs of this diagnosis.

Unlike dementia, delirium has an acute onset, motor signs (tremor, myoclonus, asterixis), slurred speech, altered consciousness (hyperalert/agitated or lethargic, or fluctuations), hallucinations may be florid. EEG shows pronounced diffuse slowing.

Brain biopsy for dementia

Clinical criteria are usually sufficient for the diagnosis of most dementias. Biopsy should be reserved for cases of a chronic progressive cerebral disorder with an unusual clinical course where all other possible diagnostic methods have been exhausted and have failed to provide adequate diagnostic certainty 11).

A biopsy may disclose CJD, low-grade astrocytoma, and AD among others. The high incidence of CJD among patients selected for biopsy under these criteria necessitates appropriate precautions; see Creutzfeldt Jakob disease.

In a report of 50 brain biopsies performed to assess the progressive neurodegenerative disease of unclear etiology, 12) the diagnostic yield was only 20% (6%were only suggestive of a diagnosis, 66% were abnormal but nonspecific, 8% were normal). The yield was highest in those with focal MRI abnormalities. Among the 10 patients with diagnostic biopsies, the biopsy result led to a meaningful therapeutic intervention in only 4.

Treatment

Outcome

At the global level, dementia is the leading cause of dependence and disability among the elderly.

Screening

Canonical definitions of the dementia construct encompass deficits in both cognition and function, but most screening instruments for possible dementia address only cognitive abilities. Free-Cog is a recently described brief screening instrument for dementia designed to address not only cognitive but also functional abilities.

A pragmatic test accuracy study of Free-Cog was undertaken in consecutive patients seen over 1 year in a secondary care setting. The performance of Free-Cog for diagnosis of dementia and mild cognitive impairment (MCI) was compared to that of Mini-Addenbrooke's Cognitive Examination (MACE).

In a cohort of 141 patients (prevalence of dementia and MCI 11 and 32%, respectively) both Free-Cog and MACE were quick and easy to use and acceptable to patients. Both tests had high sensitivity (1.00) and large effect sizes (Cohen's d) for diagnosis of dementia, but Free-Cog was more specific. For diagnosis of MCI, Free-Cog lacked sensitivity (0.58) but was specific (0.81), whereas MACE was sensitive (0.91) but not specific (0.35). Weighted comparison suggested equivalence for dementia diagnosis but a net benefit for MACE regarding MCI diagnosis.

Free-Cog is an acceptable and accurate test for dementia screening in a dedicated cognitive disorders clinic, but it appears less sensitive than MACE for the identification of MCI 13).

Case series

Liu et al., aimed to evaluate the sex differences in the prevalence of nonvascular cognitive impairment and the risk factors among the elderly in rural China screened with the Mini-Mental State Examination (MMSE).

Between 2014 and 2015, a population-based cross-section study was conducted to collect basic information among the elderly aged 60 years and over. Those participants with the previous history of stroke or heart disease were excluded in this study. Nonvascular cognitive impairment was assessed using the MMSE scores.

The prevalence of cognitive impairment was 32.4% overall, 25.6% in men and 38.1% in women. In the multivariate analysis, older age and lower education were risk factors both in men and in women; older, large waist circumference was a protective factor for cognitive function in men; higher blood pressure was the risk factor in women.

These findings suggest that it is crucial to manage and control hypertension and improve educational attainment in order to reduce the prevalence and burden of nonvascular cognitive impairment among low-income residents, both men and women, in rural China 14).


Tabei et al., aimed to determine whether neuropsychological deficits and brain atrophy could predict the efficacy of non-pharmacological interventions. Forty-six participants with mild-to-moderate dementia were monitored for 6 months; 25 underwent an intervention involving physical exercise with music, and 21 performed cognitive stimulation tasks. Participants were categorized into improvement (IMP) and no-IMP subgroups. In the exercise-with-music group, the no-IMP subgroup performed worse than the IMP subgroup on the Rivermead Behavioural Memory Test at baseline. In the cognitive-stimulation group, the no-IMP subgroup performed worse than the IMP subgroup on Raven's Colored Progressive Matrices and the cognitive functional independence measure at baseline. In the no-IMP subgroup, voxel-based morphometric analysis at baseline revealed more extensive gray matter loss in the anterior cingulate gyrus and left middle frontal gyrus in the exercise-with-music and cognitive-stimulation groups, respectively. Participants with mild-to-moderate dementia with cognitive decline and extensive cortical atrophy are less likely to show improved cognitive function after non-pharmaceutical therapy 15).

Research

References

1)
Consensus Conference. Di erential Diagnosis of Dementing Diseases. JAMA. 1987; 258:3411–3416
2)
Fleming KC, Adams AC, Petersen RC. Dementia: Diagnosis and Evaluation. Mayo Clin Proc. 1995; 70:1093–1107
3)
Reitz C, Brayne C, Mayeux R. Epidemiology of Alzheimer disease. Nat Rev Neurol. 2011;7:137–152.
4)
Hely MA, Reid WG, Adena MA, Halliday GM, Morris JG. The Sydney multicenter study of Parkinson's disease: the inevitability of dementia at 20 years. Mov Disord. 2008;23:837–844.
5)
Kowal SL, Dall TM, Chakrabarti R, Storm MV, Jain A. The current and projected economic burden of Parkinson's disease in the United States. Move Disord. 2013;28:311–318.
6)
Larner AJ. Neurological update: dementia. J Neurol. 2014 Feb 6. [Epub ahead of print] PubMed PMID: 24500494.
7)
Jiang J, Dong Y, Huang W, Bao M. General anesthesia exposure and risk of dementia: a meta-analysis of epidemiological studies. Oncotarget. 2017 Jul 24. doi: 10.18632/oncotarget.19524. [Epub ahead of print] PubMed PMID: 28767391.
8)
Lipowski ZJ. Delerium (Acute Confusional States). JAMA. 1987; 258:1789–1792
9)
Pompei P, Foreman M, Rudberg MA, et al. Delerium in Hospitalized Older Persons: Outcomes and Predictors. J Am Geriatr Soc. 1994; 42:809–815
10)
Petersen RC. Acute Confusional State: Don't Mistake it for Dementia. Postgrad Med. 1992; 92:141–148
11)
Hulette CM, Earl NL, Crain BJ. Evaluation of Cerebral Biopsies for the Diagnosis of Dementia. Arch Neurol. 1992; 49:28–31
12)
Javedan SP, Tamargo RJ. Diagnostic Yield of Brain Biopsy in Neurodegenerative Disorders. Neurosurgery. 1997; 41:823–830
13)
Larner AJ. Free-Cog: Pragmatic Test Accuracy Study and Comparison with Mini-Addenbrooke's Cognitive Examination. Dement Geriatr Cogn Disord. 2019 Jul 17:1-10. doi: 10.1159/000500069. [Epub ahead of print] PubMed PMID: 31315124.
14)
Liu W, Wu Y, Bai L, Ni J, Tu J, Liu J, Deng Q, Ning X, Wang J. Sex Differences in the Prevalence of and Risk Factors for Nonvascular Cognitive Function in Rural, Low-Income Elderly in Tianjin, China. Neuroepidemiology. 2018 Aug 9;51(3-4):138-148. doi: 10.1159/000490496. [Epub ahead of print] PubMed PMID: 30092579.
15)
Tabei KI, Satoh M, Ogawa JI, Tokita T, Nakaguchi N, Nakao K, Kida H, Tomimoto H. Cognitive Function and Brain Atrophy Predict Non-pharmacological Efficacy in Dementia: The Mihama-Kiho Scan Project2. Front Aging Neurosci. 2018 Apr 12;10:87. doi: 10.3389/fnagi.2018.00087. eCollection 2018. PubMed PMID: 29706882; PubMed Central PMCID: PMC5906569.
dementia.txt · Last modified: 2019/07/18 11:23 by administrador