Mapping dementia and cognitive decline in testamentary capacity

Cognitive assessment is central to the evaluation of testamentary capacity. Such assessment is currently performed in a subjective, unreliable and non-standardized manner. Dementia, a cognitive illness, poses one of the largest threats to testamentary capacity in modern society. A better understanding of the ways in which dementia related cognitive impairment can affect a testator's ability to meet the relevant legal criteria to make a will is needed. A review of the literature over the past ten years focusing on what cognitive abilities are required to satisfy the legal criteria for testamentary capacity has highlighted an alarming scarcity of work in this area. There is little discussion spanning beyond general acknowledgement of the importance of memory and executive function. The specifics of how cognitive impairment impacts the four limbs of Banks v Goodfellow are rarely addressed. Several additional areas of cognitive function of importance to assessing testamentary capacity are the subject of this article.

Medial temporal lobe function during emotional memory in early Alzheimer's disease, mild cognitive impairment and healthy ageing: an fMRI study

BACKGROUND

Relative to intentional memory encoding, which quickly declines in Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD), incidental memory for emotional stimuli appears to deteriorate more slowly. We hypothesised that tests of incidental emotional memory may inform on different aspects of cognitive decline in MCI and AD.

METHODS

Patients with MCI, AD and Healthy Controls (HC) were asked to attend to emotional pictures (i.e., positive and neutral) sequentially presented during an fMRI session. Attention was monitored behaviourally. A surprise post-scan recognition test was then administered.

RESULTS

The groups remained attentive within the scanner. The post-scan recognition pattern was in the form of (HC = MCI) > AD, with only the former group showing a clear benefit from emotional pictures. fMRI analysis of incidental encoding demonstrated clusters of activation in para-hippocampal regions and in the hippocampus in HC and MCI patients but not in AD patients. The pattern of activation observed in MCI patients tended to be greater than that found in HC.

CONCLUSIONS

The results suggest that incidental emotional memory might offer a suitable platform to investigate, using behavioural and fMRI measures, subtle changes in the process of developing AD. These changes seem to differ from those found using standard episodic memory tests. The underpinnings of such differences and the potential clinical use of this methodology are discussed in depth.

Estimated pre-morbid IQ effects on cognitive and functional outcomes in Alzheimer disease: a longitudinal study in a treated cohort

BACKGROUND

Cognitive reserve is thought to influence the degree of neuropathology needed for diagnosis of Alzheimer disease (AD). Cognitive reserve can be operationally defined as the hypothesized capacity of the mature adult brain to sustain the effects of disease or injury without manifesting clinical symptoms of AD, but sufficient to cause clinical dementia in an individual possessing less cognitive reserve. Its effect on the subsequent course of AD is less clear. Pre-morbid IQ is a useful measure of cognitive reserve.

METHODS

We studied 659 consecutive patients with AD at a tertiary referral memory clinic. Patients were assessed on six cognitive tests at baseline. Activities of Daily Living (ADL) were measured on the Instrumental Activities of Daily Living (IADL) scale and Physical Self-Maintenance Scale (PSMS). The National Adult Reading Test (NART) was used to estimate pre-morbid IQ. Patients were followed up after starting a cholinesterase inhibitor over 78 weeks. Mixed general linear models estimated the effects of NART on cognition and ADL.

RESULTS

Three hundred and fifty-five patients had NART scored with a mean estimated pre-morbid IQ of 104.7 (standard deviation 18.5). NART increased overall cognitive ability by 2.7% for every 10 IQ points (p < .001). There was a trend for an effect on the change in cognition over time (p = .065) with higher NART associated with improvement of cognitive ability over time. After adjusting for age and sex, a 10 point increase in NART was associated with an improvement of 2% in ADL scores, but this effect was explained by NART's influence on contemporaneous cognitive ability.

CONCLUSION

Our data support the hypothesis that cognitive reserve continues to have a limited influence on cognition after AD has been diagnosed and thus, indirectly, has an impact on ADL.

Relationship between behavioural and psychological symptoms of dementia and cognition in Alzheimer's disease

BACKGROUND

Behavioural and psychological symptoms of dementia (BPSDs) are common. It is unclear whether associations are stronger with the absolute cognitive level or that relative to premorbid mental ability.

METHODS

The Neuropsychiatric Inventory (NPI) was administered to carers of patients with Alzheimer's disease (AD). Patients underwent cognitive testing with the National Adult Reading Test (NART) to estimate premorbid IQ and 6 tests of current cognitive function.

RESULTS

556 patients, mean age 77.3 years, had NPI scores. The total NPI score correlated significantly with most cognitive test scores, but multi-linear regression identified NART-IQ as the only significant cognitive predictor (beta=-0.17, p=0.008). Principal component analysis of the 10 NPI domains extracted 3 components corresponding to mood, frontal and psychotic factors. The NPI mood factor correlated significantly with NART-IQ (rho=-0.14, p=0.014) and lexical verbal fluency (rho=-0.09, p=0.034) only. The NPI frontal factor correlation with NART-IQ approached significance (rho=-0.11, p=0.053). The NPI psychotic factor correlated significantly with the Mini-Mental State Examination (rho=-0.15, p<0.001) and the Hopkins verbal learning test (rho=-0.11, p=0.013) scores.

CONCLUSION

The relationship between BPSDs and cognition in AD is weak and largely explained by premorbid IQ. There is a stronger relationship between current cognition and psychotic symptoms.