Depressed or not depressed? that is the question

Population Base Rates and Disease Course of Common Psychiatric and Neurodegenerative Disorders

Knowledge of population base rates of neurological and psychiatric disorders is fundamental for diagnostic decision making. Consideration of relevant probabilistic information can improve diagnostic efficiency and accuracy. However, such data continue to be misused or underutilized, which can lead to misdiagnoses and negative patient outcomes. The aim of the current review is to create an easily accessible and comprehensive reference of existing age of onset as well as prevalence and incidence data for common neurodegenerative and psychiatric disorders in adults. Relevant epidemiological data were compiled from well-respected and frequently-cited textbooks and scholarly studies. Reviews were collected from PubMed, and publicly-available sources were gathered from Google Scholar. Results are organized and presented in several tables and a figure, which can be used as a diagnostic guide for students and clinicians across healthcare disciplines.

The cognitive neuropsychology of depression in the elderly

BACKGROUND

The cognitive impairment of older depressed patients with late- as opposed to early-onset illness may show important differences, in that patients with early onset may suffer predominantly from impaired episodic memory, and those with late onset mainly from reductions of executive function and processing speed.

METHOD

We searched Medline and EMBASE as well as individual papers' reference lists for relevant publications, recording comparisons in neuropsychological test results between early-onset depression (EOD), late-onset depression (LOD) and healthy volunteers. Effect sizes are presented for cognitive domains, such as executive function, processing speed, episodic memory, semantic memory and mental state examination.

RESULTS

Patients with LOD showed greater reductions in processing speed and executive function than patients with EOD and controls. Both patient groups showed reduced function in all domains, except mental state, compared with controls.

CONCLUSION

Pronounced executive deficits are typical of the late-onset patients described in published studies, while episodic memory impairment is not specific to early-onset illness. Possible reasons and confounders are discussed.

Verbal memory performance of patients with a first depressive episode and patients with unipolar and bipolar recurrent depression

Depression is usually associated with episodic memory impairment. The main clinical features of depression associated with that memory impairment are not clearly defined. The main goal of that study was to assess the role of the diagnostic subtypes and the number of depressive episodes on the memory performance of acute unipolar (UP) and bipolar (BP) depressed patients.Twenty-three patients with a first major depressive episode (FE), 28 patients meeting DSM-IV criteria for UP recurrent depression (UR) and 18 BP patients with recurrent depression were compared with 88 healthy subjects on a verbal episodic memory task. Patients suffering from a first depressive episode did not show verbal memory impairment as compared to normal controls. Unlike FE patients, UR and BP patients exhibited verbal memory deficits with impaired free recall and normal cued recall and recognition. The memory deficits of the UR and BP patients was present in the first free recall trial. Depressed patients improved their memory performance across the three trials of the task at the same rate than normal controls. Our results suggest that the number of depressive episodes has a negative influence on verbal memory performance of acute depressed patients. The effects of the repetition of the depressive episodes are not modulated by the subtypes of depression and may reflect sensitization to the cognitive impact of depression associated with increasing prefrontal dysfunction.

Influence of age and executive functioning on verbal memory of inpatients with depression

BACKGROUND

Despite many studies demonstrating memory and executive impairments in young and old depressed patients, the relationships between age, executive functioning and memory have not been evaluated in depression. The aim of this study was to investigate if older patients were more vulnerable than younger patients to the impact of depression on memory and if the differences between young and old depressed could be related to executive functioning.

METHODS

Forty-nine inpatients, with unipolar and bipolar depression, ranging in age from 19 to 72 years were compared with 70 controls on a verbal memory task. Age cut-off of 45 years was used as a categorical variable to divide subjects into subgroups. A subset of patients (n=41) was also evaluated with the modified version of the Wisconsin Card Sorting Test and separated into a non-dysexecutive group and a group of patients with mild-executive impairment.

RESULTS

Depressed patients exhibited memory deficits with a pattern of memory failure -- impaired free recall and normal cued recall and recognition -- interpreted as a retrieval problem. Both age and executive function influenced memory performance in depression, however neither group x age interaction nor age x executive status interaction were significant. Multiple regression analysis showed that free recall scores were related to age and psychomotor retardation in depressed patients.

CONCLUSION

Age and executive functioning have different influences on the memory performance of depressed patients. Our findings support an 'executive memory decline hypothesis' in young as well as old depressed patients. The memory deficits in depression may be associated with both trait and state factors and raise questions about the long-term cognitive functioning of patients with recurrent affective disorders.

Late neurocognitive changes from neurological damage following coronary bypass surgery

A detailed case study with neuropsychological data over a 26-year period was used to explore the relationship between neurocognitive vulnerability preoperatively and subsequent neurocognitive decline identified several years postoperatively. Guidelines regarding the importance of neuropsychological assessment of intelligence, attention, memory, language, and visual-spatial planning and organizational skills are provided. Such evaluations clarify postoperative treatment planning because rehabilitation of cardiac patients with premorbid neurocognitive deficits poses special rehabilitation problems. With a detailed neurologic history as part of the preoperative evaluation, healthcare providers can identify acute and subtle risk factors for postoperative neurologic syndromes. This may lead to interventions designed to provide increased patient and family support.

Conversational discourse abilities following severe traumatic brain injury: a follow-up study

The major aim of this study was to describe the conversational abilities of a group of severely injured TBI speakers, at a minimum of 2 years post-injury. The association between conversational impairment and (a) selected measures of executive function and (b) psychosocial handicap was also examined. Twenty-four members of the group of 26 severely injured TBI speakers who had initially been assessed between 3 and 6 months post-injury were reviewed at a minimum of 2 years post-injury (mean = 2 years, 10 months). At initial assessment, TBI speakers were compared with non-TBI orthopaedic patients and with a group of university students. At follow-up, however, they were compared only with the orthopaedic patients. Conversational assessment was carried out using a modified form of Damico's Clinical Discourse Analysis. As a group, the TBI speakers' conversational abilities did not improve over time. There was, however, a subgroup (n = 8) of speakers who did improve, and these could be distinguished by greater initial severity of injury and a significantly longer period of speech-language pathology intervention than the speakers who either remained the same or worsened over time. Modest associations between conversational discourse skills and measures of executive function and a measure of psychosocial handicap were identified. These findings indicate that disruptions in conversation persist into the longer term. More assiduous efforts may need to be made to (a) identify subtle discourse changes in the early months after injury and (b) engage TBI speakers in speech-language pathology services. Such services are also required over a longer time frame, in community-based models of service provision.

Reduced cognitive functions in a group of whiplash patients with demonstrated disturbances in the posture control system

Past studies examining whether or not cognitive changes actually have occurred as a result of a whiplash (WL) accident have produced varying results. The aim of this study was to identify possible cognitive dysfunctions in a group with persistent problems after whiplash due to injuries to the posture control system and related structures. The whiplash subjects (n = 23) were selected on the basis of their reduced gain in the Smooth Pursuit Neck Torsion test (SPNT). The WL group differed significantly from a closely matched control group on tests of learning and memory, and prolonged divided attention and concentration. After attempting to rule out other ways of interpreting these differences (such as pain, depression, medication, and premorbid health problems), these data were interpreted as lending support to the notion of a causal connection between the disturbed posture control system and some cognitive malfunctions.

Emotional disturbances and their interaction with neuropsychological deficits

The interaction and relationships between neuropsychological tests (which are principally oriented to intellectual and cognitive abilities) and tests of personality and emotional status are complex, but nevertheless important in the clinical assessment of brain-damaged persons. Are indications of emotional disturbances to be expected as a direct consequence of brain damage? If so, how can the indications of emotional disturbances be differentiated from results obtained with psychiatrically disturbed (non-brain-damaged) subjects? Some authors have presumed that emotional disturbances, such as depression, acute anxiety, etc., in their own right cause impaired performances on neuropsychological tests, whereas other authors have proposed that brain damage predisposes the individual to demonstrate evidence of emotional disturbances. If emotional disturbances cause impairment on neuropsychological tests, why is it that so many emotionally disturbed persons without brain damage tend to perform normally on neuropsychological tests? This review of relevant publications considers (1) different general approaches to these questions and their implications for neuropsychology, (2) evidence of differential sensitivity to brain damage of neuropsychological and emotional instruments, (3) the sensitivity and specificity of self-assessments and complaints of head-injured subjects, (4) MMPI findings among head-injured subjects and in interaction with neuropsychological measurements, and (5) principles and guidelines that may be of value in clinical application of findings reported in the literature.

Dementia of depression or depression of dementia in stroke?

This study describes the correlation between changes in mood symptoms assessed by the Hamilton Depression Rating Scale (HDRS) and intellectual impairment assessed by the Brief Cognitive Rating Scale (BCRS) and Mattis Dementia Rating Scale (MDRS) in 166 unselected 1-year survivors after stroke, in whom post-stroke depression (PSD) has previously been described and validated. The course of intellectual impairment associated with PSD was compared with the course of intellectual impairment in non-PSD patients. In general, improvement in mood symptoms was correlated with an improvement in intellectual function. However, in 53 PSD patients improvement in intellectual performance was absent, despite the fact that the patients reported being significantly less distressed by dementia symptoms. Antidepressive medication did not lead to any improvement in MDRS score. No evidence was found to support the hypothesis of 'dementia of depression'. To the contrary, the findings indicate 'depression of dementia'.

Correlates of depression in cognitively impaired hospitalized elderly referred for neuropsychological assessment

The prevalence and quality of depression (Geriatric Depression scale), were studied in groups of cognitively impaired patients referred for neuropsychological assessment from a short-term assessment ward (Group A), and from long-term care wards (Group B). Cognitively intact assessment ward patients served as a comparison group (Group C) to control for effects of hospitalization on mood. The prevalence of depression did not differ for the cognitively impaired short-term assessment and long-term care groups. However, cognitively impaired patients in Group A had a higher prevalence of depression than cognitively intact patients in Group C. GDS scores did not correlate with measures of severity of cognitive impairment or of self-care disability in Groups A and B, although elevated GDS scores were significantly correlated with higher Verbal IQ scores in these groups. Analysis of individual GDS items responses suggested that depression in cognitively impaired elderly tends to be characteristic of adjustment disorder rather than Major Depression.

Dissociation between declarative and procedural learning in dementia and depression

Declarative and procedural learning were assessed in patients with probable Alzheimer's Disease (AD) and major depression, patients with AD and no depression, patients with major depression but no dementia, and a group of age-comparable nondemented and nondepressed normal controls. AD patients showed significant deficits in declarative but not in procedural learning, while depressed nondemented patients showed the opposite pattern (i.e., a significantly worse procedural than declarative learning). Patients with both AD and major depression showed a similar learning pattern to the AD nondepressed group (relatively preserved procedural learning but severe deficits in declarative memory). These findings provide further evidence for the independence between declarative and procedural learning, and demonstrate their different vulnerability in dementia and depressive-like states.

Effects of short-term transcutaneous electrical nerve stimulation on memory and affective behaviour in patients with probable Alzheimer's disease

The present study investigated whether a 30-minute-a-day transcutaneous electrical nerve stimulation (short-term TENS) might improve disturbances in memory and affective behaviour in patients with probable Alzheimer's disease. The hypothesis was derived from former studies in which beneficial effects on memory and affective behaviour of Alzheimer patients were found after a daily application of 6-h TENS and a 30-min tactile stimulation. The present data reveal that short-term TENS improved some aspects of verbal and visual short-term and long-term memory. Moreover, patients who had undergone this treatment felt, e.g., less dejected, less gloomy, less irritable, more cheerful, more active, and more alert. They were also more interested in social contacts and participated more in daily activities. After a period of 6 weeks following treatment, the effects on memory as well as the improvements in affective behaviour partially remained.

Pseudodementia: a slow death

The clinical term "pseudodementia" has remained a permanent nosological entity in the literature for over 100 years. Indeed, recognition of the fact that clinical symptoms associated with reversible neuropsychiatric conditions can mimic irreversible disorders was known as early as the middle of the 19th century. The importance of the term lies in the inherent assumption that the presenting dementia is not real, or is at least reversible, and therefore treatable. Nonetheless, there continues to be controversy regarding the validity and appropriate clinical use of the term. This article reviews the evolution and clinical utility of the term pseudodementia and attempts to redirect investigative efforts toward an understanding of the neuroanatomical substrates that underlie depression and cognitive impairment in the elderly. Based on a critical analysis of the relevant literatures, a subcortical-frontal neuroanatomical substrate of late-life depression is supported. Further, the presence of leukoaraiosis, as measured by magnetic resonance imaging, is proposed as a potential neurobiological marker that contributes to the depressed mood, cognitive impairment, and later cognitive deterioration of some elderly depressed.

Cognitive and psychopathological change in degenerative disease in the elderly

Neuropsychological studies of declining cognitive ability and increasing psychopathology in degenerative neurological diseases in the elderly suggest the following: (1) the physiological basis for affective and thought disorder remains elusive; (2) cognitive capacity and primary psychopathology are not clearly related in degenerative disease; rather neuropsychological studies in this area illustrate a dissociation between accessory (secondary) symptoms of psychopathology and cognitive changes; (3) accessory symptoms of thought disorder may be associated with disorders of the basal ganglia; and (4) current nosology of affective and thought disorders is probably not appropriate when dealing with onset of psychopathology in the elderly. There is a need to closely attend to logical inference in neuropsychological data from this group of patients, and to clearly differentiate primary from secondary symptoms of affective and thought disorders.