Depression vs. Dementia: How Do We Assess? - Alzheimer ...
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Originally published in The Canadian Review of Alzheimer’s Disease and Other Dementias, September 2009, pages 17-21.
Copyright STA Communications.
Depression vs. Dementia:
How Do We Assess?
Depressive disorder and dementia are common in older people, and may occur separately or
together. Diagnosis is often challenging because of the frequency of symptoms which are
common to both disorders. Unfortunately, underdiagnosis of depression results in missed
opportunities to improve functioning, decreased quality of life and possibly even increased
mortality. Yet, overdiagnosis of depression may result in unnecessary adverse effects of
psychotropic medications. This article suggests approaches to differential diagnosis.
By Lilian Thorpe MD, PhD, FRCP
D ementia increases with age, with
an overall prevalence in Canada
of 8% in those 65 years and older,
These include dysthymic disorder,
depressive episodes of a bipolar dis-
least two contradictory directions of
potentially causal influence. One
order, mood disorders secondary to a hypothesis suggests that depression
2.4% in those aged 65 to 74 years, medical disorder (such as hypothy- leads to dementia, and another that
11.1% in those aged 75 to 84 years, roidism), mood disorders secondary suggests that dementia itself leads
and 34.5% in those aged 85 years and to a substance, adjustment disorders to depression.
older.1 Alzheimer’s disease (AD) is and bereavement. Depressive disor- The depression-to-dementia direc-
thought to be the most common type der is commonly seen in all stages of tion is supported by evidence that
of dementia in all age groups. How- adult life and, while its prevalence is depressive disorder is a risk factor for
ever, younger age groups are more slightly lower in the elderly,4 its developing dementia in later life6 and,
likely than older age groups to be sequelae are probably greater in more consistent with this, the best-studied
diagnosed with other dementias, such frail people, exerting a more deleteri- people with a biological predisposition
as frontotemporal dementia and vas- ous effect on functional abilities and to develop AD (those with Down
cular dementia.2 even increasing the length of stay for Syndrome) are thought to have a high
Major depressive disorder is also hospitalizations related to primary risk of suffering from depression.7 The
common, but is only one of a number medical conditions.5 Depressive dis- association between depression and
of disorders listed in the Diagnostic order in seniors can occur as part of a later development of dementia is still
and Statistical Manual of Mental lifelong recurrent disorder, or it can not completely understood. One possi-
Disorders (DSM-IV)3 with prominent present for the first time in old age. It bility is that depression is an early, pro-
depressive symptoms (Table 1).3 is frequently concurrent with other dromal phase of dementia,8 and is
medical and mental disorders, includ- caused by the same pathophysiologic
ing various dementias. initiators that result in dementia. There
Lilian Thorpe MD, PhD, FRCP is also evidence that depression is
Clinical Professor of Psychiatry,
and Professor of Community
Relationships Between associated with damage to brain loca-
Health and Epidemiology, Dementia and Depression tions integral to cognitive processes,
University of Saskatchewan Dementia and depression have a such as the hippocampus, possibly
Saskatoon, Saskatchewan complicated relationship, with at by decreasing neurogenesis.9 This
The Canadian Review of Alzheimer’s Disease and Other Dementias • 17Vascular Dementia
those with dementia,17,18 although a
Table 1
recent Danish study suggests that this
DSM-IV Mental Disorders with Prominent Depressive may now have changed, at least in
Symptoms3
Denmark.19 Underdiagnosis of dep-
• Major depressive disorder ression in demented seniors is clearly
• Dysthymic disorder undesirable, as depressive disorders
• Bipolar disorder (depressive episode) in the demented elderly have been
• Mood disorders secondary to a general medical condition associated with additional burden, as
• Mood disorders secondary to a substance (such as a medication) described above. Undertreatment
• Adjustment disorder with depressed mood
with antidepressants may also result
in over treatment of depression-asso-
• Bereavement
ciated behaviors with benzodi-
azepines and possibly neuroleptics.
process may lower the threshold for depression in dementia by using four Adverse effects of benzodiazepines
later observable cognitive loss, even- different scales in the same popula- and neuroleptics are well recognized
tually increasing age-adjusted demen- tion, and found that between 27.5% and include increased falls, decreased
tia rates. Behaviors associated with and 53.4% of people with mild AD alertness, extrapyramidal side effects,
depression, such as heavy alcohol and between 36.3% and 68.4% with decreased mobility, decreased func-
uses and vascular risk factors like moderate to severe AD were found to tioning and increased mortality.
cigarette smoking,10 may also inde- rate positive for depression. Studies Efforts have been made to increase
pendently increase later cognitive comparing differences in the preva- the recognition of depression in those
loss, while medications prescribed to lence of carefully diagnosed depres- with dementia, and widely used
treat depression, especially those sive disorders between matched instruments such as the Minimum
with strong anticholinergic effects, demented and non-demented popula- Data Set20 include quality indicators
could conceivably have adverse cog- tions are not frequent, but suggest that to alert administrators of patients with
nitive effects, although this effect is motivational deficits in dementia may likely depression who are not being
likely more transient. be the greatest difference between treated with antidepressants. Review
The dementia-to-depression dir- these groups, rather than typical of these quality indicators may pre-
ection in the potentially causal rela- DSM-IV major depressive disorder.13 cipitate discussion with attending
tionship between the two disorders is However, regardless of the exact physicians, who have the opportunity
supported by findings that people prevalence of formally diagnosed to institute appropriate treatment.
with dementia appear to have a high- depressive disorder in dementia, it Unfortunately, this process may
er prevalence of depression.11 does seem that depressive syndromes also result in an overdiagnosis of
However, prevalence rates vary wide- are very common in those with depressive disorder due to the high
ly depending on the study population dementia, and that this comorbidity prevalence of behavioral symptoms
(psychiatric outpatients, Alzheimer causes increased deficits in function- in dementia such as apathy and reac-
registries, old-age homes), instru- ing, increased problematic behav- tive mood symptoms, which overlap
ments used, and diagnostic defini- ior,11 increased nursing-home place- with those seen in major depressive
tions. Most problematically, the term ment,14 increased caregiver stress,15 disorder. Treatment with antidepres-
depression is used to denote different and increased mortality.16 sants is increasingly also known to be
clinical concepts, which are not associated with adverse effects, most
always equivalent to a diagnosis of Under- and Overdiagnosis of problematically in older, frail popula-
DSM-IV major depressive disorder. Depression in Dementia tions. Anticholinergic effects of the
Muller-Thomsen et al12 illustrated Depressive disorder has long been tricyclic antidepressants may cause
large variability in the diagnosis of thought to be underdiagnosed in confusion, constipation, urinary reten-
18 • The Canadian Review of Alzheimer’s Disease and Other DementiasDepression vs. Dementia
tion, and visual-accommodation prob-
Table 2
lems. Postural hypotension may cause
falls, and cardiac effects are particu- DSM-IV Symptoms of a Major Depressive Episode
larly dangerous in overdose. Newer • Depressed mood
medications, such as selective sero- • Markedly diminished interest or pleasure
tonin reuptake inhibitors (SSRIs) and • Significant weight change
venlafaxine, were initially felt to be
• Changes in sleep patterns
much safer, but have been increasing-
• Psychomotor agitation or retardation
ly associated with different, rather
• Fatigue or loss of energy
than fewer, adverse effects.
• Feelings of worthlessness, excessive or inappropriate guilt
Gastrointestinal side effects and
• Diminished ability to think or concentrate
sleep disturbances appear to be more
• Recurrent thoughts of death, suicidal ideation or suicidal actions
common with this group of medica-
tions. Recent research has suggested
that SSRIs are no less likely than tri- ing behavior, decreased initiative le,26 the Geriatric Depression Scale,27
cyclic antidepressants to cause falls.21 and interest (apathy), psychomotor the Hamilton Depression Rating
They are also associated with a higher agitation, and poor concentration (in Scale,28 the Montgomery and Asberg
prevalence of hyponatremia,22 and advanced dementia) are common in Depression Rating Scale29 and the
most recently research has suggested dementia without depression. Reac- Zung scale.30 Although these scales
they increase fragility fractures.23 tive symptoms such as anxiety and vary considerably in how much they
Finally, SSRIs have been associated tearfulness are also seen frequently are affected by impairments in lan-
with increased apathy,24 even in those in dementia without depression, and guage, awareness and comprehen-
who have been appropriately diag- may be related to retained aware- sion, none is useful in the later stages
nosed with depression and have ness of deficits in the early stages of of dementia. Of greater usefulness in
responded to this medication. dementia, poor coping skills and patients with advanced dementia are
disorientation in the later stages, or the Dementia Mood Assessment
Challenges in the Diagnosis to the mood lability accompanying Scale31 and the Cornell Scale for
of Depression in Dementia vascular brain disease (which com- Depression in Dementia.32
Diagnosing depressive disorder in monly overlaps with AD). However, the gold-standard differ-
the context of dementia is often dif- Much less common in dementia ential diagnosis of depression in
ficult due to overlapping symptoms without depression are consistent dementia is a careful clinical assess-
between depression and dementia, sadness, marked morning mood ment, which includes obtaining infor-
communication problems and lack of worsening, feelings of worthlessness mation directly from the patient and
insight. Behavioral and psychologi- or excessive or inappropriate guilt, from collateral sources, ideally those
cal symptoms of dementia (BPSD) recurrent thoughts of death, suicidal with good knowledge of the person.
are integral parts of the clinical pres- ideation or suicidal actions. This assessment should include:
entation of dementia, although this • Careful symptom history
is often thought of as a disorder of Approach to Clinical including:
progressive cognitive decline. Diagnosis - detailed description;
BPSD includes many of those A variety of instruments have been - time course and progression
symptoms also seen characteristi- developed to screen for depression in of symptoms; as well as
cally in DSM-IV depressive disor- the cognitively intact population. - association with other
ders. Of the core symptoms of These include the Beck Depression confounding factors such as
depressive disorder, listed in Table 2, Inventory,25 the Centre for Epide- environmental stressors which
sleep disturbances, changes in eat- miological Studies-Depression Sca- include:
The Canadian Review of Alzheimer’s Disease and Other Dementias • 19Vascular Dementia
Table 3
Typical Presentations of Mood Symptoms in Dementia and Depression
Symptom Dementia Depression
General response to Frequent lack of concern or denial about symptoms. Amplification of and excessive
cognitive and functional preoccupation with deficits.
decline
Mood Normal most of the time. Unhappiness is reactive Subacute (weeks) onset of pervasively
to circumstances and fluctuates. Labile, especially sad mood, most of the day and nearly
with vascular dementia. Mood often brightens every day. Doesn’t brighten much with
with stimulation and support. stimulation.
Interest, initiative Gradual loss of interest and initiative (apathy) over a Subacute loss of interest and pleasure
longer period of time (years rather than weeks). Not over a few weeks, frequently
accompanied by statements of sadness, tearfulness, accompanied by sad mood and affect,
or other distress. Still enjoys activities in a structured and occasionally statements of guilt,
environment. hopelessness and self-harm.
Eating behavior and Gradual loss of weight (over months to years) which Subacute changes (weeks) in appetite
weight is common in dementia. Large increases in weight leading to increase or decrease
may be secondary to decreased activity, medications, in weight.
and hyperorality in patients with frontal behavioral
presentations (more common in frontotemporal
dementia like Pick’s Disease).
Sleep Gradual disruption of the sleep-wake cycle (over Subacute changes in sleep over a few
months to years) due to brain changes of dementia, weeks (increase or decrease).
resulting in frequent night-time wakening and
daytime sleeping.
Psychomotor agitation Gradual (months to years) increase in agitation, Subacute (weeks) onset, often worse
generally worse during the latter part of the day in the morning, may be present
(sundowning). Patient much worse in unfamiliar persistently throughout the day.
settings (catastrophic reaction), and often seeking Generally accompanied by other
people or places from earlier life experiences. depressive symptoms such as nihilistic
statements or excessive guilt.
Psychomotor retardation Seen infrequently in mild to moderate dementia, Subacute onset of psychomotor
but occasionally in very advanced dementia, and retardation (over weeks) in severe
may be mimicked by Parkinson’s dementia (facial depression.
masking, slow motor functioning) or advanced
Pick’s Disease.
Energy Generally a normal energy level, but reduced Subacute decrease in energy and
activity due to poor initiation related to decreased increased complaints of fatigue.
executive functioning.
Guilt or worthlessness Uncommon, although transient statements of Common in severe depression, usually
worthlessness might be seen in times of stress in accompanied with low mood as well
those with preserved awareness of their own decline. as changes in appetite and sleep.
Concentration and Concentration is normal in early dementia, but Subacute loss of concentration and
thinking impaired in late dementia. Thinking ability declines sustained focus. Often indecisive and
throughout the course of dementia. concerned about making mistakes.
Suicidal thoughts Uncommon. Common.
and actions
20 • The Canadian Review of Alzheimer’s Disease and Other DementiasDepression vs. Dementia
- pain; consistently low mood and affect thy without associated sadness, cry-
- poor nutritional status; that does not respond to ing, or changes in sleep or appetite
- other medical stimulation; hopelessness, are unlikely to represent a depressive
conditions; and expressions of guilt; feelings of disorder, whereas consistently sad
- recent changes in worthlessness; and thoughts of mood or affect, not brightening dur-
medications. self-harm. ing interpersonal contact and associ-
• Particular attention should be • Laboratory investigations, such ated with subacute changes in sleep
paid to depressive symptoms as hematology, thyroid function, and appetite are much more likely to
which are less common in electrolytes, vitamin B12, and represent depressive disorder that
dementia alone such as: drug levels of medications, requires medical treatment. Table 3
- hopelessness; known to have a propensity to summarizes mood symptoms seen in
- expressions of guilt; cause mood symptoms. depression and dementia, with a brief
- feelings of worthlessness; and In addition to the above, neuro- discussion about their more typical
- thoughts of self-harm. imaging might be performed to presentation in each disorder.
• Frontal symptoms, such as explore the potential contribution of
disinhibition, perseveration and vascular pathology to mood lability Conclusion and Treatment
decreased initiative, suggest and apathy, and to rule out other neu- Issues
dementias with a strong frontal rologic problems such as normal- Sometimes it is very difficult to make
component rather than depression. pressure hydrocephalus. a firm diagnosis of depression in the
• Information about family After this assessment, the clini- context of dementia, especially when
history of mood disorders, cian has to weigh the information the dementia is very advanced. The
previous personal history of obtained, taking into account the clinician will occasionally choose to
depression and previous response likelihood that the accumulated instigate treatment regardless of
to therapy for depression. information represents depression diagnostic certainty, weighing the
• Direct interview of the person, rather than dementia alone. For possible benefits versus potential
paying particular attention to: example, isolated symptoms of apa- adverse outcomes of treatment.
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