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Pseudobulbar affect (PBA) can be challenging to differentiate from the symptoms of various neurological diseases with which it is associated. In patients with Alzheimer’s disease (AD) and dementia such a diagnosis can be particularly difficult as illustrated by a case of an elderly male with sudden tearful outbursts, which is reported and discussed here. PBA attacks are often incorrectly attributed to emotion or distress in response to memory loss or a result of depression or dementia. PBA is common, affecting between 10–40 % of people with AD but is frequently not detected or is misdiagnosed. Multiple authors have published clinical criteria for identifying PBA; in sum, it is described as a condition affecting the brain with episodes of laughing or crying that are sudden and unpredictable, occur without warning and are excessive, exaggerated, or not appropriate to the stimuli and are involuntary and difficult to control. Differentiating PBA from depression and other behavioral disturbances in AD and dementia is helpful to patients by identifying a specific cause of their symptoms and enabling appropriate management. Various different approaches have been taken in the treatment of PBA. A combination of dextromethorphan and quinidine hasbeen shown in well-controlled trials and in clinical use to control the symptoms of PBA associated with several neurological diseases including AD and to reduce the burden on patients and their caregivers.
An estimated 5.3 million people in the US have Alzheimer’s disease (AD),1,2 the incidence of which increases with age.3 Defined as a ‘progressive mental deterioration manifested by loss of memory, ability to calculate, and visual-spatial orientation, confusion and disorientation;’4 the symptoms, clinical presentation, and prognosis of AD are well known among clinicians. It is also widely appreciated that AD may be associated with any of several neuropsychiatric symptoms including depression, agitation, anxiety, insomnia, and paranoia.
Given this potentially complex clinical background, onset of frequent crying episodes may seem neither unusual nor worthy of further exploration. However, this apparently sensible and pragmatic thinking is flawed, since it risks overlooking a major cause of such symptoms —pseudobulbar affect (PBA). Affecting as many as two in five people with AD5,6—but widely under-recognized by clinicians—this important condition must be considered when assessing patients like PJ (seeBox 1).
The Differential Diagnosis
The psychiatrist treating PJ assumed that he had depression associated with AD. However, the clinical symptoms described and the lack of therapeutic response raise the possibility of treatment-resistant depression or that depression is not the problem. A list of differentialdiagnoses would therefore include the following:
PJ’s crying episodes make it hard to ignore the possibility that he is depressed. However, it is important to note that frequent crying spells do not automatically indicate depression and that tearfulness is not a necessary or sufficient criteria in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-V) for diagnosing major depressive disorder (MDD).7 Also, while many health care providers make the seemingly reasonable assumption that increased crying is a symptom of depression, there are limited data to support the idea that depressed patients have an increase in crying episodes.8–11 Evidence against the assumption includes the work of Rottenberg and colleagues,9 who compared crying episodes in patients with MDD to those in a control group of non-depressed participants, by using a cry-evoking stimulus (a sad movie). They found that crying was no more likely in the depressed than in the control group, who, surprisingly, showed greater crying-related emotional activity than the MDD group. Also, using patient self-reported episodes of crying to compare depressed versus non-depressed elderly individuals, Hastrup and colleagues11 found only a weak link in increased frequencies of crying episodes among elderly adults with depression, and concluded that crying could not be interpreted as a symptom or sign of depression.
Establishing if a patient with AD also has depression is further complicated by the overlapping features of the two conditions. For example, apathy and poor concentration are common symptoms found in dementia; anhedonia and nihilism also commonly occur in depression.7,12 Neurovegetative symptoms are common in both conditions and include disturbances in sleep and appetite, changes in weight , decreased sexual desire, decreased energy, psychomotor retardation or agitation, and poor concentration.13,14 Interestingly, depressed patients with apathy or neurovegetative symptoms may have fewer episodes of crying compared with someone without depression. When crying is caused by underlying depressive illness, it is associated with the patient’s reports of pervasive low mood.
Behavioral disturbances are common in people with AD and other forms of dementia. For example, Lyketsos and colleagues studied patients with dementia using a screening questionnaire followed by a clinical assessment and found that 61 % exhibited one or more mental or behavioral disturbances within the past month, with apathy, depression, and agitation/aggression being the most common forms.15 Given their nature and high prevalence, behavioral disturbances could account for crying in patients with dementia.
Essential crying is an uncommon disorder and is included for completeness.15 Those with essential crying have a lower threshold for weeping when compared with the normal population.14 This may be a variant of the emotional domain of temperament. Patients with the condition do not necessarily have an underlying neurological disorder.16,17 Crying would not be a new finding, but rather characteristic of the individual.
PBA is a disorder of regulation of emotional expression, caused by neurological disease or injury affecting the brain. PBA is characterized bysudden, uncontrollable episodes of crying, laughing, or both. These episodes are excessive, inconsistent with or disproportionate to circumstances or the patient’s underlying mood at the time.18
PJ’s symptoms are most likely to reflect either behavioral disturbances of dementia or PBA. The former will be familiar with clinicians who have experience caring for people with dementia, but what exactly is PBA and how can it be identified and managed?