Neuropsychological Assessment Plan for Depression-dementia Patient

Experiencing stressful life events, such as bereavement, have been observed to act as a precedent for the onset of Alzheimer’s disease (AD) (Reich, 2011). Meanwhile, the DSM-V recognizes grief and bereavement as a trigger for major depression (Pies, 2014). Depression on itself, however, has been recognized as both a risk factor (Thorpe, 2009) and a prodromal feature of dementia (Singh-Manoux et al., 2017).

The current evaluation report will propose a neuropsychological assessment plan for the patient in Case scenario 3 taking into account the vicious cycle of depression-dementia (co)-occurrence. The proposed assessment will involve: patient’s history acquired through a semi-structured interview and a test of premorbid functioning, a screening test, memory tests with a focus on episodic memory and a depression measure.

Background information and Premorbid Ability

Prior to the formal cognitive assessment a history taking interview both from the patient and a relative (his wife) is crucial forasmuch as it can provide essential knowledge about the degree of insight by the patient, word finding difficulties, inappropriate behaviour, or accuracy of autobiographical memories by comparing the patient’s interview with the informant’s (Cooper & Greene, 2005). To help with determining premorbid function, background information regarding educational and occupational history should be obtained. Informant description provided by his wife would also be useful to determine the level of the patient’s insight. This also might be useful to determine the cause of depression since insight has been linked to depressed mood in AD (Horning, Melrose, & Sultzer 2014). If previous medical tests and scanning have been conducted, they should be investigated beforehand to decide what potential deficits to expect and thus choose the assessment procedure (Morris & Brookes, 2012).

The Clinical Dementia Rating Scale (CDR; Hughes et al, 1982) is a highly reliable semi-structured interview with both the subject and the informant for acquiring qualitative background information. It has well-structured memory and orientation sections, which will be of good use for the present scenario. Since the occupation of the subject is a farmer, he is expected to come from a low socio-economic status (SES). Furthermore, his symptoms are not indicative of a severe stage of AD but rather of a mild beginning stage. For these two purposes, CDR-SB, which is the score obtained by the sum of squares, would be more relevant for this specific case. The CDR-SB has been found sensitive both to mild dementia and lower education background (Lima, Castilhos, & Chaves, 2017). 

For a quantitative assessment of premorbid ability, the re-standardised version of the National Adult Reading Test (NART, Nelson & Willison, 1991) is suggested. It has been justified with AD and brain damage patients and has been shown to outperform demographic judgements. However, the use of both should give a better clarity about the patient’s history.

Screening Test

The Addenbrooke’s Cognitive Examination (ACE; Mathuranath et al, 2000) has been found to be sensitive to the early stages of AD, which makes it appropriate for the present case. Dudas, Berrios and Hodges (2005) suggested that a total score below 88 is predictive of an organic score, and anything above this cut-off might well be because of an affective disorder.

Recently, after a thorough evaluation of the sensitivity of the revised version of the ACE – ACE-R (Mioshi et al, 2006) towards late-life onset depression Rotomskis et al (2015) concluded that the test could be used as an accurate diagnostic tool to differentiate between AD and depression and this should be done by interpreting the results in accordance with the distinct neuropsychological profiles of the two diseases. Severely poor performance on the attention and orientation, memory, language and category fluency subsets should be indicative of AD, while only mild impairment in the overall ACE-R score with deficits in memory and verbal fluency signalize for depression (Dubas et al., 2005).

With some of its weaknesses from previous versions being addressed, in the current assessment the latest version of the ACE – ACE-III (Hsieh et al, 2013) should be used.

Memory Tests

The original Wechsler Memory Scale (WSM; 1945) was specifically devised for people with dementia, aphasia and disorientation. In this scenario, the later version Wechsler Memory Scale – Revised (WMS-R; 1987) will be used both because of its large scope of cognitive functions evaluations and its reported ability to differentiate between demented and depressed patients on the delayed recall task (Rushing, Sachs-Ericsson, & Steffens, 2014). Impairments of delayed recall and long-term memory rather than executive functioning would be associated with AD. Depressed patients might not be good at free recollection because of impaired attention (Leposavić et al., 2010). Autobiographical and semantic memory are expected to be intact in the early stages of dementia, however a low score on these domains should be further addressed.

A further memory measure in terms of dementia-depression differentiation could be the Paired Associates Learning (PAL) task. This test assesses visual memory and new learning and has been shown to accurately differentiate between depressive pseudodementia and dementia (Blackwell et al., 2005, Swainson et al., 2001). Patients who usually perform poorly on it are at risk of developing AD and early AD patients show difficulties in visuospatial processing (Jahn, 2013).

Depression Measure

In the present case, diagnosis of depression is as important as the diagnosis of AD so that a strategic further assessment plan or referral can be undertaken. Underdiagnosis of depression can lead to failure of functioning improvement, reduce quality of life or even raise the chance of mortality (Thorpe, 2009).

Although being specifically designed for demented population, the Cornell Scale for Depression in Dementia (CSDD; Alexopoulos, Abrams, Young & Shamoian, 1988) has also been proved equally valid to detect depression in non-demented population (Kørner, 2006). Unlike the Geriatric Depression Scale (GDS; Yesavage, 1982), which measures depression via a self-rating scale, one of the main advantages of the CSDD is that the final score is determined by semi-structured interviews both with the patient and the informant based on the clinician’s observations and impressions. As it is quite time-intensive, it is expected to be exhaustive and accurate enough for the current case.

Conclusion

Even though this proposed plan of assessment consists of multiple qualitative and quantitative measures for AD and depression, the neuropsychologist’s own behavioural observations of the subject during the assessment are also very important to reach the correct conclusions. For instance, some of the signs of dementia overlap with the symptoms of late-life depression, such as apathy and cognitive impairment. However, apathy, or the lack of motivation and interest, is more present in dementia than depression (Katon et al., 2010). Therefore, being sensitive and considerate to all the cues during an assessment would be the ideal approach. 

Appendix
Tests to be used during the assessment in the given order

1)     Clinical Dementia Rating Scale (CDRS)

Hughes, C. P., Berg, L., Danziger, W., Coben, L. A., & Martin, R. L. (1982). A new clinical scale for the staging of dementia. The British journal of psychiatry, 140(6), 566-572.

2)     National Adult Reading Test (NART)

Nelson, H. E., & Willison, J. (1991). National Adult Reading Test (NART). Windsor: NFER-Nelson

3)     Addenbrooke’s Cognitive Examination III (ACE-III)
Hsieh, S., Schubert, S., Hoon, C., Mioshi, E., & Hodges, J. R. (2013). Validation of the Addenbrooke’s Cognitive Examination III in frontotemporal dementia and Alzheimer’s disease. Dementia and geriatric cognitive disorders, 36(3-4), 242-250.

4)     Wechsler Memory Scale – Revised (WMS-R)
Wechsler, D. (1987). Wechsler memory scale-revised manual. San Antonio, TX: The Psychological Corporation.

5)     Paired Associates Learning (PAL) Task

Sahakian BJ, Morris RG, Evenden JL, et al (1988) A comparative study of visuospatial memory and learning in Alzheimer-type dementia and Parkinson’s disease. Brain 111 (Pt 3:695–718)

6)     Cornell Scale for Depression in Dementia (CSDD)

Alexopoulos, G. S., Abrams, R. C., Young, R. C., & Shamoian, C. A. (1988). Cornell scale for depression in dementia. Biological psychiatry, 23(3), 271-284.

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