Actigraphy as a new objective measure for apathy in schizophrenia

Apathy concerns a quantitative reduction of voluntary, goal-directed behaviour
that impairs daily functioning. It is a prominent and severely debilitating
aspect of several psychiatric disorders, most notably schizophrenia. However,
measuring apathy is still a challenge (Clarke et al., 2011). There are a number
of reliable and valid clinical instruments, mainly questionnaires, available to
quantify apathy in terms of core aspects of apathy, including a lack of
initiative and reduction of motivation and goal-directed behavior (Clarke et
al., 2011). However, in order to evaluate the presence of apathy, a certain
degree of knowledge of the clinician or the informant into the patients*
functioning, or insight of the patient in daily activities is required. This
hampers the objectivity of a measurement. Moreover, the clinicians* judgment of
the severity of apathy of a certain patient is possibly influenced by the
average level of apathy in their patient cohort, which could lead to
underestimation of apathy in severely ill cohorts. Therefore, more objective
measures of apathy are warranted (Clarke et al., 2011). Since apathy has been
associated with reduced initiative and goal-directed behavior, measuring
physical activity in patients might be informative on the presence or severity
of apathy (Konig et al., 2014).

The main objective is to measure activity levels using an accelerometer in
healthy participants, patients with schizophrenia scoring low or average on
apathy (< 27 on the apathy items of the Apathy Evaluation Scale (clinician
rated; AES-C), Morch-Johnsen et al., 2015) and patients with schizophrenia
scoring high on apathy (* 27 on the AES-C) to investigate whether actigraphy
can be used as an objective measure to designate the presence or severity of
apathy in patients with schizophrenia. Activity levels are already being
measured in a schizophrenia group scoring high on apathy as part of the Apathy
study (Randomized controlled trial of neurostimulation treatment for apathy in
schizophrenia, METC2013.137). The two reference groups (healthy group and the
schizophrenia group scoring low or average on apathy) will be added in this
add-on study to answer two questions: 1) is there a difference in activity
levels between healthy individuals and schizophrenia patients, 2) can
actigraphy be used to separate schizophrenia patients that score low/average on
apathy from patients that score high on apathy?

Activity levels will be measured during two consecutive weekend days, wherein
participants are free from work, by means of an accelerometer that is worn
(continuously) around the wrist. Before wearing the accelerometer, the
schizophrenia reference group will be interviewed to confirm diagnosis and
evaluate the presence and severity of apathy and other apathy and schizophrenia
related symptoms using the MINI, AES, TEPS, SANS and PANSS measures. Apathy and
anhedonia will also be evaluated in the healthy reference group using a
self-rated questionnaire (AES-S and TEPS). Furthermore, the healthy reference
group will fill in the SCL-90 to evaluate symptoms of psychopathology.

Actigrahy is well-tolerated, feasible, ambulatory, and non-invasive and will be
of no harm or bother to the participants (Walther et al., 2015). The
schizophrenia reference group will receive ¤15,- as a compensation for the
interviews. The healthy reference group will receive ¤10,- (the amount is less
because less time is spent on clinical evaluation). Furthermore, the interviews
and questionnaires are not expected to be a high burden to the participants.